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NexaTM Power Module User's Manual MAN5100078

1. 5100078 OUTPUTS Requirement Definition Quantity Power Rated Power Capacity at Standard Conditions BOL 1200 W Voltage Operating voltage range 22 V to 50 V Voltage at Rated Power 26 V Start up Time Minimum time to achieve Rated Power from a 2 minutes Cold Start condition Emissions Noise Maximum noise emission at 1m 72 dBA Water Maximum quantity of liquid water produced at 870 mL hr Rated Power Physical Dimensions LxWxH 56 x 25 x 33cm Mass Total system mass 13 kg Lifetime Operating Life Minimum number of operating hours before 1500 hours EOL Cyclic Life Minimum number of start up amp shut down cycles 500 before EOL Shelf Life Minimum storage non operation before EOL 2 years INPUTS Requirement Definition Quantity Fuel Purity Lowest acceptable concentration of hydrogen 99 99 vol Pressure Allowable range of inlet supply pressure 70 1720 kPa g Acceptable Maximum total inert fluids including helium 0 0196 vol Impurities argon nitrogen and water vapour Maximum CO and CO combined 2 ppm vol Maximum total hydrocarbon 1 ppm vol Maximum oxygen 500 ppm vol Consumption Maximum fuel consumption at Rated Power 18 5 SLPM Power Current Ripple Maximum acceptable current ripple at 120 Hz 24 7 5 Conditioning with respect to average DC net output current 35 peak peak DC Power Voltage Allowable range of input voltage 18 V to 30V Supply Power Maximum pow
2. 79 LIFETIME CHARACTERISTICS eiecti cde Eee eee teer ed beca e eee de ete 100 WARNING AND FAILURE ALARM LIMITS enne rene rennen nennen nennen nere nr 102 TROUBLESHOOTING CHECKLIST Commercial Confidential viii Nexa Power Module User s Manual BALLARD MAN5 100078 3 2 05 Introduction The Nexa power module is a small low maintenance and fully automated fuel cell system designed to be integrated into products for portable and back up power markets It is ready to integrate into a variety of products for household and commercial use The Nexa power module is not designed for medical applications or mission critical use The Nexa system provides up to 1200 watts of unregulated DC power at a nominal output voltage of 26 VDC With the use of an external fuel supply operation is continuous limited only by the amount of fuel storage Using hydrogen fuel the Nexa module is extremely quiet and produces zero harmful emissions permitting indoor operations This manual describes the Nexa system design and operation It provides technical product specifications performance characteristics and interface requirements for installation and operation Important safety information is also included Please review the contents of this manual before operating your Nexa module and contact Ballard Customer Service if you have any q
3. eene enne ee ieaie nieee 95 FIGURE 38 NOISE EMISSIONS AT 1 METER cc cccssssscecssssececesscecsessececsesaececsnseecsesaeeecsesseseceeseecsesaeeecsesaeeeceeaeeeseseteceagas 96 FIGURE 39 TRANSIENT RESPONSE sinere nr ener 97 FIGURE 40 POWER DE RATING CURVES c c c cccsseeccsessnsecsesssseesecceceeseccecsessususesceseesusteccesassesescesessusssecsenassdessneeesesneess 98 3 2 05 Commercial Confidential vii Nexa MANS 1 Power Module User s Manual 00078 BAL ARL LIST OF TABLES TABLE 1 TABLE 2 TABLE 3 TABLE 4 TABLE 6 TABLE 7 TABLE 8 TABLE 9 TABLE 10 TABLE 11 TABLE 12 TABLE 14 TABLE 15 TABLE 16 TABLE 17 TABLE 18 TABLE 19 TABLE 20 TABLE 21 TABLE 22 TABLE 23 TABLE 24 TABLE 25 TABLE 26 TABLE 27 TABLE 28 3 2 05 TRANSMITTED STATUS WARNING AND ALARM CODES ccssscssccecsessssscececececsesseaeceeececsessaaeeeeececeessaeeeeececeenes 7 TRANSMITTED TRANSDUCER SIGNALS cccssssccssssececssscecsessececsssaececseceecsesseeecsesaeeecessecsesaeeecsessessceaeesseaeeeessgas PRODUCT SPECIFICATION DEFINITIONS NEXA PRODUCT SPECIFICATION aah htt ta M E NU et lan i RD Ma Ere HYDROGEN INLET CONNECTION ceessccsessscecssseececssssecseensecseseececeessecseseesecseaaeseceesaecseessecsenaeeeseesaeesseeneesees PROCESS AIR INLET C
4. 8 8 EE L A SS gt 21 Mew or sO lt 7 m c2 A B D E M N o ia Time State CodeFailure Cor Warning C Last Comr Stack P Stack V v Stack A Fuel P ba H2 Leak Cons 02 96 Air T C Purge Cell Battery V 1 37440 7 0 ol 0 14 23 33 42 86 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 35 42 86 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 37440 7 0 0 14 23 35 429 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 35 42 86 0 47 4 98 3 35 0 01 20 9 24 06 0 03 25 25 37440 7 0 0 0 14 23 35 42 86 0 47 4 98 3 35 0 01 20 9 24 06 0 03 25 25 374407 0 0 0 14 23 35 42 86 0 47 4 98 3 35 0 01 20 9 24 06 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 47 4 98 3 35 0 01 20 9 24 06 0 03 25 25 374407 0 0 0 14 23 37 42 86 0 47 4 98 3 35 0 01 20 9 24 06 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 374407 0 0 0 14 23 37 42 86 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 47 4 98 3 35 0 01 20 9 24 0 03 25 25 37440 7 0 0 14 23 37 42 86 0 47 4 98 3 35 0 0 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 47 4 98 3 53 0 01 20 9 24 0 03 25 25 37440 7 0 0 14 23 37 42 86 0 47 4 98 3 53 0 0 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 47 4 98 3 53 0 01 20 9 24 0 03 25 25 37440 7 0 0 0 14 23 37 42 86 0 45 4 98 3 53 0 0 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 38
5. 600 30 0 200 10 0 PAO L Peo PCO L PAI L PCL L 100 5 0 PA2 L Pee PC2 L L L PC3 PAS L P54 veo PC4 0 PAS L 5 PCS H H H DATA LOGGING COMMUNICATION File 3 E Period Log a Serial Port On POO gt Pro Li 0000 Start Pot E E mi m Cor OF gt Aor PD2 Ext load PE2 GasValve2 PF2 Li Qe SSeS GasValvet Gas Valve3 PD4 Purge Valve PE4 Gas Valve 4 TOOLS PDS Stack Conn H PES RS 485 Tx H PFS H Air Pump Start Stop J 0 Read EEPROM Set Restartable PDS PES PFE umm f F9 F12 2vRal PE FanPower PF Li Cooling Fan Start Stop J 0 ul d z 4 db sb oi Figure 14 NexaMon OEM Main Screen Opening the NexaMon OEM software does not engage the Nexa module in any way nor does it initiate serial communications with the unit To initiate serial communications and receive real time data updates from the Nexa module one must toggle the Communication Start Switch F5 The monitoring logging and diagnostic features of the NexaMon OEM software are only available when the Communication Start Switch has been toggled to the ON position 3 2 05 Commercial Confidential 37 Nexa Power Module User s Manual BAL 2n MAN5 100
6. Description Specification Composition Ambient air Pressure Atmospheric Flow 3600 slpm maximum Connection None Table 9 Cooling Air Inlet Connection 2 3 5 Cooling Air Outlet The cooling air outlet expels warmed air to the ambient surroundings after absorbing heat from the fuel cells Hydrogen and water purged from the fuel stream is released into the cooling air stream Hydrogen released from the pressure relief vent port during an over pressure condition also mixes with the cooling air outlet stream Cooling air outlet specifica tions are detailed in Table 10 Description Specification Composition See cooling air inlet Maximum Allowable Pressure 0 35 kPa 1 4 inches of water Drop or Back pressure Temperature 17 above inlet stream Flow See cooling air inlet Connection None External ducting is recommended to separate the cooling air outlet stream from the process air inlet Table 10 Cooling Air Outlet Connection 2 3 6 Output Power Connections The output power connections deliver the unregulated DC output power generated by the fuel cell stack Specifications for the output power connection are provided in Table 11 Description Specification Power net 0 W minimum at idle 1200 W maximum continuous at BOL Voltage unregulated 22 50 VDC at beginning of life standard operating conditions sea level 30 Maximum Imposed Current Ripple 24 796 rms at 120
7. Table 12 Battery Input Connection Communications Connector The communications connector provides input output and communication signals between the Nexa power module controller and host equipment Communications connection specifications are provided in Table 13 Description Specification Communications Standard RS 485 serial Baud 9600 Start Bits 1 Commercial Confidential 20 Nexa Power Module User s Manual MAN5100078 Data Bits 8 Parity none Stop Bits 1 Configuration Full duplex asynchronous data transmission Data Protocol Serial Line Internet Protocol SLIP Internet RFC 1055 Transmit 3 2 05 Message Period Message Length Receive Message Length 200 ms continuous 43 bytes to 143 bytes 5 bytes Solenoid Valve Output Signal Logic High 13 5 VDC open Low 0 VDC closed Type Open drain to ground Voltage 13 5 VDC Current 0 5A Load Contactor Output Signal Logic High 13 5 on closed circuit Low 0 off open circuit Type Open drain to ground Voltage 13 5 VDC Current 0 2A On Off Input Signal Logic Current flow on No current flow off Type Optically coupled Voltage Drop Across Input 1 4 VDC maximum Current 3 5 10 mA maximum Input Impedance 1 ko Connector 42 way AMP 638184 6 male header Mates with 16 way AMP 174514 1 plug and 040 AMP 345160 1 female receptacles Pinout J4 B1 Reserved J4 B2 Reserved J4
8. NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 indicates the hydrogen fuel consumption rate at maximum power is less than or equal to 18 5 slpm A detailed fuel consumption curve is provided in the Performance Characteristics section of this guide NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 also indicates the maximum hydrogen fuel flow rate at maximum power during anode purging is 20 0 slpm Greater hydrogen flow rates are required during an anode purge because of 1 reduced fuel cell stack operating pressure and 2 excess hydrogen required to purge water out of the flow channels The maximum instantaneous hydrogen purge rate is approximately 500 cc min while the average hydrogen purge rate measured over a period of continuous operation is about 60 cc min Excess hydrogen is purged into the cooling air
9. 7 If during the next 5 seconds after the internal loads are transferred to the stack any of the variables mentioned in 6 above fail to be met then the system transfers internals back to the battery Normal Operation Running State The fuel cell will start in approximately 15 seconds if no operating faults are detected during the startup sequence Operational faults may include hydrogen leak present low oxygen concentration low hydrogen pressure high fuel cell stack temperature low fuel cell stack voltage high fuel cell stack current low cell voltage and low purge cell voltage Once the start up sequence is completed the system enters Normal Operation At this point the power relay is closed and power is available from the fuel cell system Normal Operation is the only state in which power can be drawn from the fuel cell In this state all functions necessary for fuel cell operation under dynamic loading conditions are performed by the system components and no current should be drawn from the battery Normal Shut Down Stopping State If the start line is turned off the fuel cell system will go through a Normal Shutdown sequence If the stack has been in RUNNING or WARNING state for less than 60 seconds then the System Shutdown Procedure is called to stop the stack and return it STANDBY state Refer to section 7 1 7 If the stack has been operating for more than 60 seconds the system will initiate the following Shutdown Seq
10. Nexa Power Module User s Manual BAL 2n AN 8 Product Integration MAN5100078 of ten cycles are performed followed by shaking at any noted resonance frequencies for 10 minutes The Nexa system passed all such tests with no damage The Nexa power module has also been designed and tested to withstand shock loads described in the IEC 68 2 31 Basic Environmental Testing Procedures Drop and Topple The standard essentially states that the DC module shall be subjected to a free fall drop test from a height of 1 2 m onto a hard surface concrete or steel Any failures directly or indirectly emanating from such a load condition shall not present a safety hazard The Nexa system has been tested to such standards with an aluminum frame providing support in lieu of an OEM enclosure M 8 4 Design for Maintenance The Nexa power module was design with ease of maintenance in mind Components such as the humidity exchanger hydrogen sensor fuel regulator can be removed and replaced within minutes More complex components such as the fuel cell stack and cooling fan assembly require longer repair times due to their complexity and location in the system The OEM integrating the Nexa into a commercial product should consider designing a product with maintainability in mind The OEM should consider providing access to replace items which are more likely to wear and require replacement such as the humidity exchanger or air pu
11. 4 2 13 3 2 05 Changing the Serial Port The Serial Port menu allows you to choose a serial communications port from COM to COM 8 The default port is COM 1 when NexaMon OEM is first run The port state is stored on shutdown The Start switch must be turned off to access the Serial Port menu The serial port applies to all program communications The selected port must be the one that is hooked up for system communication To change the serial port Set the Start switch on the main screen to Off This enables the serial port menu Select a serial port by dropping the serial port menu or by pressing F2 and select the desired COM number as illustrated in Set the start switch to On If the selected port is not hooked up the Serial Timeout light will come on DATA LOGGING File Period Log On File csv F0 Off 0 25 is 2s 10s 60s 10m COM5 l TOOLS COM 6 Air Pump Start Stop 0 Read EEP Cooling Fan Start Stop E 0 En y mcd d b Z Figure 21 Changing the Serial Port Commercial Confidential 53 Nexa Power Module User s Manual BAL 2n itu MAN5100078 5 Mechanical Interface 5 1 3 2 05 Mechanical Interface This section provides a detailed description of the mechanical interface requirements for the Nexa power module The physical layout and dimensions of the power plant are shown along with the location of interface co
12. BOL lt 18 5 slpm Maximum Hp fuel flow rate Maximum fuel flow rate at maximum lt 20 0 slpm 3 2 05 Commercial Confidential 57 Nexa Power Module User s Manual MAN5100078 BAL AR 5 Mechanical Interface 3 2 05 Requirement Description Quantity Nominal purge gas flow Average purge gas flow rate measured 60 cc min rate over a period of continuous operation Maximum purge gas flow Maximum instantaneous purge gas flow 8 500 cc min rate rate Stack leak rate BOL Fuel leak to external at 350 mbarg 10 cc min Stack leak rate EOL Fuel leak to external at 350 mbarg 50 cc min Stack pressure relief valve Stack PRV setting 96 kPa g 14 psig PRV Stack PRV reseal pressure 75 kPa g 11 psig NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 Hydrogen Interface Specifications The fuel connection to the Nexa system utilises a 45 flared tube fitting male for 1 4 inch OD tubing Refer to Figure 22 for the connection location and tolerances Ensure that the hydrogen supply lines to the power module are provided with vibration isolation
13. Nexa Power Module User s Manual BAL AKL MAN5 100078 Nexa Power Module Nexa 310 0027 Power Module User s Manual 5 000 001 Series PBS Proprietary Notice Declaration Copyright 2003 Ballard Power Systems Inc All rights reserved This document is subject to change without notice Document Number MAN5100078 Revision Release Date June 16 2003 3 2 05 Commercial Confidential i Nexa Power Module User s Manual BAL ARD A MANS 100078 Nexa Power Module i Revision History Revision Record Rev co Description Revised by Date CO07704 Change of 02 warning level from Chris Gibson 2005 02 28 19 5 to 19 2 OD CO08184 Added note to minimum FZ 2004 10 22 acceptable fuel pressure specification OC CO07613 Updated ISTA procedure from 1 NK 2004 03 30 to 1A amp 1B OB CO06417 Preventative Maintenance NK 2004 02 10 Schedule Added OA CO Nexa Installation and MT 2003 06 16 Integration Guides merged into one document 3 2 05 Commercial Confidential ii Nexa Power Module User s Manual BAL ARL MAN5100078 Nexa Power Module 3 2 05 Confidentiality The information contained in this document is the intellectual property of Ballard and is Commercially Confidential No part of this document may be reproduced or transmitted in any form or by any means electronic or mechanical for any purpose without the
14. Nexa Power Module User s Manual BAL 2n An 7 Software and Communications enter a Non Restartable mode for safety reasons In these cases the system must be reset by a BALLARD Field Service or Customer Support representative 7 3 Communications A serial port is used to communicate information about fuel cell operation to the OEM and to communicate diagnostic and instructional information from the OEM to the Nexa system The serial port interface uses full duplex communication a pair of wires for transmission and a pair of wires for reception The full duplex communication allows asynchronous data transmission without needing to handle bus contention The differential voltage levels used by the serial port are defined by the RS 485 standard The following items outline the features of the serial port communications 1 Communication is asynchronous at 9600 baud with the Nexa system sending a data stream to the OEM approximately once every 200 ms 2 SLIP Serial Line Internet Protocol Internet RFC 1055 is used to encode and decode the messages sent between devices The SLIP code uses a one byte tag 0xCO at the beginning and at the end of each message Three other special characters called escape characters 0xDB OxDC and 0 are required to handle cases where 0xCO must occur in the middle of the message 3 The message from the Nexa power module to the OEM will always includ
15. an 5 Mechanical Interface Cooling Air Interface A cooling fan maintains the desired fuel cell stack operating temperature at 65 C Cooling air is drawn into the sides of the squirrel cage fan as shown in Figure 23 Air is ducted to the base of the stack and flows vertically upward through cooling channels between fuel cells Cooling air exhaust exits at the top of the fuel cell stack To maximise the capacity of the Nexa cooling system ensure that the fan intake draws in fresh ambient air External cooling air ducting must be added to the fuel cell stack in order to ensure that coolant exhaust does not mix with the fan intake If the operating environment is dusty it is recommended that the cooling air be filtered to remove particulates Use temperature resistant and non conductive materials for the housing and ducting channels Furthermore when integrating power conditioning equipment with the Nexa system ensure that the waste heat from the inverter or battery charger is separately ducted out of the unit enclosure Avoid dumping waste heat from power electronics into the cooling fan intake as this will compromise the Nexa cooling system capacity The cooling air exhaust should be ducted over the hydrogen leak detector of the hydrogen delivery assembly In this way the leak detector continuously monitors hydrogen levels purged into the cooling air stream The detector also checks for external leaks from the fuel cell stack tha
16. 50 ms in duration Execute Rejuvenation procedure on shut down for firmware revisions 00 03 01 or greater Call Ballard Field Service for further support Check pressure in hydrogen fuel tanks Check pressure regulator settings of storage tanks Ensure delivery pressure is within limits provided in interface specifications Measure and confirm 12 V signal is applied to the solenoid Listen for solenoid clicking Call Ballard Field Service for detailed diagnostics Check the Nexa system leak detector readings using software interface Verify using hand held leak detector Snoop all connections using soapy water Repeat Low Fuel Cell Stack Voltage troubleshooting suggestions above Contact Ballard for further support Check the top of the fuel cell stack for blockage of the cooling channels Check air intake filter and the air outlet line for blockage 104 Nexa Power Module User s Manual 5100078 DESCRIPTION OF WARNING OR FAILURE Low Purge Cell Voltage Fuel Leak Detected 3 2 05 POSSIBLE CAUSE Hydrogen fuel supply is contaminated Onboard current sensor is un calibrated CVC fingers not in proper contact with fuel cell plates CVC fingers not properly plugged into CVC board Non Operating Performance Loss NOPL or fuel cell contamination air or fuel supply Fuel cell failure Purge Valve Stuck Open Faulty Regulator incorrect supply pressure Blocke
17. Battery Voltage ADC Ballard use only Fuel H2 Leak ADC Bridge Voltage ADC Ballard use only 12 3 Voltage ADC Ballard use only DAC A Loop ADC Ballard use only DAC B Loop ADC Ballard use only Ballard use only Spare ADC Ballard use only Ground ADC Ballard use only Pump DAC digital to analog conversion Ballard use only Fan DAC Ballard use only System Run Time Seconds System Life Time Seconds Stack Start Time Seconds Stack Stop Time Seconds Stack Run Time Seconds Stack Life Time Seconds Self Test Fault Ballard use only Purge Status 0 CLOSED 1 OPEN 2 DISABLED Resuscitation Status 0 OFF 1 2 DISABLED Resuscitation Number over the lifetime of the power module ASCII Text Start Line status light 0 OFF 1 ON Cell Voltage Check status light 0 OFF 1 Table 15 NexaMon OEM Data Logging Format 3 2 05 Commercial Confidential 44 Nexa Power Module User s Manual MAN5 100078 3 2 05 A Installation A portion of a sample data logging file is illustrated below Each row corresponds to a single time stamp Each column of the data table corresponds to the parameters listed in Table 15 S Edt view Insert Format Tools Data Window Help 1 avi 0 B Zu
18. Serial Interface A serial port is used to communicate information about fuel cell operation to the OEM and to communicate diagnostic and instructional information from the OEM to the fuel cell system The serial port interface uses full duplex communication a pair of wires for transmission a pair of wires for reception and a single ground wire The differential voltage levels used by the serial port are defined by the RS 485 standard In order to connect the Nexa serial port to a computer use a RS 485 to RS 232 converter The serial port header used in the Nexa control board is designated AMP 638184 6 In order to connect to the control board use the plug designated AMP 174514 1 and receptacles AMP 173716 1 Hydrogen Tank Valve Control An external solenoid valve is also recommended for isolating hydrogen supply at the storage tank The Nexa system provides a control signal for the proposed secondary fuel solenoid so that it may be controlled in tandem wit the internal fuel solenoid Figure 27 illustrates the electrical connection for the hydrogen storage tank valve Table 23 shows the electrical interface specification for the valve control signal Description Hydrogen DC Solenoid Tank Valve Valve Actuator Operating Range Control Signal Signal Type 13 5 VDC Digital 500 mA max Normally Closed Table 23 Hydrogen Storage Tank Valve Interface Specifications Interface Connectors The foll
19. W 75 61 Air Stoic 13 22 PORT A 0x09 00001001 PORT B 0x04 00000100 PORT C 0x04 00000100 PORT D OxFE 11111110 PORTE OxBF 10111111 PORTF 0x39 00111001 3 2 05 Commercial Confidential 50 Nexa Power Module User s Manual 5100078 BAL Installation Stack Voltage 850 ADCI Stack Current 130 ADC2 Fuel Pressure 129 ADC3 Purge Cell Voltage 891 ADCA Stack Temperature 547 ADC5 Oxygen Concentration 668 ADC6 Air Flow Rate 369 SPI Air Temperature Sensor 394 ADC7 MUX0 Battery Voltage 859 ADC7 MUXI H2 Leak Sensor 464 ADC7 2 H2 Sensor Leg 262 ADC7 MUX3 12 3 Volt Rail 833 ADC7 MUX4 DAC A Loopback 368 ADC7 5 DAC B Loopback 424 ADC7 MUX6 Spare 0 ADC7 MUX7 Ground 0 DACA Air Compressor 110 DACB Cooling Fan 128 Current System Run Time 0000 00 26 Total System Lifetime 0032 50 30 Current Stack Start Time 0000 00 15 Current Stack Stop Time 0000 00 00 Current Stack Run Time 0000 00 00 Total Stack Lifetime 0017 17 15 FAULT HISTORY DATA Additional fault list data here for 20 faults total Figure 19 Sample of Diagnostic Data Report 3 2 05 Commercial Confidential 51 Nexa Power Module User s Manual BAL 2n 5100078 Installation 4 2 11 4 2 12 3 2 05 Set Restartable Certain faults are non restartable and must be reset using diagnostic software before the Nexa system can be restarted In NexaMon OEM the Set
20. power To support Nexa system operation the fuel cell stack provides power to the air pump cooling fan as well as onboard sensors actuators and controllers The auxiliary power requirement at system idle is approximately 35 watts Auxiliary loads increase with increasing current primarily to support higher air pump and cooling fan duty At rated system power approximately 250 watts of auxiliary load is required Commercial Confidential 91 Power Watts Nexa Power Module User s Manual 5100078 BALLARD 9 2 3 2 05 Hydrogen Consumption SLPM 9 Performance Characteristics Hydrogen Consumption Figure 34 illustrates the beginning of life BOL Nexa system hydrogen consumption as a function of net output current and average net output power The maximum hydrogen consumption rate of the Nexa power module at rated power is less than 18 5 slpm As illustrated in Figure 34 the hydrogen consumption rate is proportional to the gross fuel cell current demand and nearly proportional to the net output current delivered 1500 1350 1200 1050 900 750 600 450 300 150 0 5 10 15 20 25 30 35 40 45 50 Net Current Amps H2 Consumption Net Power Figure 34 Hydrogen Consumption Rates Commercial Confidential 92 Power Watts Nexa Power Module User s Manual MAN5100078 9 3 Efficiency AN 9 Performance Characteristics Figure 35 illustrates the begi
21. power module transitions to STANDBY state In this state sensors and actuators are energised and the onboard microprocessor continually transmits system data and status messages When in STANDBY application of a 5V start signal to the Nexa control board will begin the STARTING sequence The hydrogen solenoid valve opens and the purge valve periodically cycles to fill the fuel cell stack with hydrogen The air pump turns on to provide air to the fuel cells Finally the cooling fan turns on to provide thermal regulation as well as dilution of purged hydrogen During this sequence the fuel cell stack voltage quickly increases from zero to normal idling levels Once a series of internal system checks are passed the Nexa module transitions from STARTING to RUNNING state This start up process typically lasts 10 30 seconds Once RUNNING state is achieved the Nexa module control board internally transfers parasitic loads from the external battery to the fuel cell stack In addition an external load relay control signal is sent to connect the fuel cell stack to load At this point power can be drawn from the Nexa module WARNING messages are transmitted should normal operating parameters be exceeded Multiple simultaneous WARNING messages are possible during normal operation Should alarm limits be exceeded the Nexa module will instantly shut down and broadcast the FAILURE SHUT DOWN status message When the 5V start signal is removed
22. power modules to Ballard must be packaged in the designated shipping crate assembles Nexa packaging must be in good condition Physical damage to the crate due to misuse or outside storage will void the warranty claim Table 5 Nexa Shipping and Storage Specification 3 2 05 Commercial Confidential Nexa Power Module User s Manual MAN5100078 BAL i 2 Specifications 2 3 Interface Specifications Interface specifications are provided for the Nexa power module to enable gas electrical and communication connections for lab installation The Nexa module interfaces are illustrated in Figure 4 Specifications for interface connections follow the figure Italicised component labels are for reference only a Hydrogen c Process i Communications b Hydrogen Inlet Air Inlet Connector Pressure Relief Vent Port Name Plate Hydrogen j Sensor wss Inlet Solenoid Valve Cell Voltage Monitor Connector Oxygen Sensor h Output Power Connectors f Cooling odi Hydrogen Air Outlet ehem 2 zx Regulator Process Siac k Air Pump il Inside 1 1 Cooling Motor Humidity Exchanger Sh p Coding Blower Mounting e Cooling Feet Air Inlet Purge Solenoid Valve Inside 3 2 05 Commercial Confidential Nexa Power Module User s Manual D MAN5100078 BAL AN J 2 3 1 3 2 05 Figure 4 Ne
23. 11 3 TROUBLE SHOOTING CHECKLIST 102 3 2 05 Commercial Confidential vi Nexa Power Module User s Manual BAL AR XL 5100078 Nexa Power Module LIST OF FIGURES FIGURE THE NEXA POWER MODULE rode tr e epe ET iets leche ORG EO tad sel 1 FIGURE 2 SYSTEM SCHEMATIC tee HEEL Wied saan ese babe e EE Ee viret 2 FIGURE 3 PEM FUEL CELL PRINCIPALS 1 theres ite 3 FIGURE 4 NEXA COMPONENT LAYOUT AND NTERFACES eee tette teet tette tette totes 17 FIGURE 5 INSTALLATION OF THE POWER MODULE 29 FIGURE 6 NEXA INSTALLATION KIT ces to edema rot RES ra Uer ia esta ua be dol trades Cs 31 FIGURE TENEXA LABORATORY TEST SET 2 etait eet de teet b meto let etd 32 FIGURE 8 INSTALLING THE NEXA SYSTEM TRAY eco a oni o dt idera ae iter ram diti 33 FIGURE 9 CONNECTING THE 24V POWER SUPPLY ccccssssesssscecessececsnseececsnececesaececsseaeeesseeecsesaececeeseeeeseeeessesaeeecseaaess 33 FIGURE 10 CONNECTING THE COMMUNICATIONS PORT isses enne enne nnne inneren rennen tirer 34 FIGURE 11 CONNECTING THE SERIAL CABLE AND 34 FIGURE 12 INSTALLING THE LOAD RELAY ccccccesssscecssssececsscceceessececsesaececeeceeceesueeecsesaececeeeecsesaeeecsesseseceeaaees
24. 42 86 0 45 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 38 42 86 0 47 4 98 3 53 0 0 20 9 24 0 02 25 25 374407 0 0 0 14 23 38 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 38 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 374407 0 0 0 14 23 38 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 374407 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 0 20 8 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 374407 0 0 0 14 23 4 42 81 0 47 4 98 3 53 0 0 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 81 0 47 4 98 3 53 0 0 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 86 0 47 4 98 3 53 0 0 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 81 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 37440 7 0 0 0 14 23 4 42 81 0 47 4 98 3 53 0 01 20 9 24 0 02 25 25 mw Log File I nif oem by C uestes 4 o 4 A S SEO r1 Figure 16 Sample of Data Logging File Commercial Confidential 45 Nexa Power Module User s Manual 5100078 BAL 4 2 10 Read EEPROM The diagnostic data download facility reads the contents of the Nexa power module con troller s non volatile electronically erasable programmable read only memory or EEPROM This data can be viewed on the host computer s monito
25. Dichloromethane Carbontetrachoride Commonly used general purpose cleaners dry cleaning and paint strippers Concern High Can irreversibly absorb on catalyst Methyl Bromide Commonly used in fumigation of industrial dry foodstuffs and produce and residentially on rugs furniture and clothing in sealed vacated homes Concern High Can irreversibly absorb on catalyst Aromatic Compounds Toluene Xylene Dyes paints gasoline coatings insecticides adhesives varathanes and corrosion inhibitors Concern Low Effects catalyst but may be removed through oxidation during normal operation Aliphatic hydrocarbons Methane Propane Octane and Kerosene Fossil fuels i e gasoline diesel natural gas propane gas paraffin Commercial products include turpentine furniture polish household cleaners and propellants Concern Low unless combustion occurs A source of nitric oxide and sulphur dioxide upon combustion Esters Perfumes general purpose cleaners pesticides cosmetics food flavours Concern Low Effects cathode but may be removed through oxidation during normal operation 3 2 05 Commercial Confidential 64 Nexa Power Module User s Manual 5100078 BAL 5 Mechanical Interface 5 7 5 7 1 3 2 05 Methanol Wood Paint strippers windshield wiper Concern Low Alcohol solution
26. Hz maximum throughout the operating range equivalent to 3596 peak to peak 3 2 05 Commercial Confidential 19 Nexa Power Module User s Manual BAL ARD MAN5100078 Connection AMP 2 321598 3 ring terminal 1 4 ID for use with STUD 74 20 UNC Pin out P1 2 Power Black P1 1 Power Red 2 3 7 2 3 8 3 2 05 Table 11 Output Power Connection Battery Connector The battery connector draws external battery power to start and shut down the Nexa power module During start up the battery remains connected for providing auxiliary loads until the Nexa module completes its start up process and is running normally Once running the fuel cell system provides its own auxiliary power The battery remains disconnected from the control board until the stack voltage falls below 18V or the Nexa module is shut down During shut down the battery is reconnected for providing auxiliary power Specifications for the battery input connection are provided in Table 12 Description Specification Voltage 18 to 30 VDC Energy Draw 60 W for 60 seconds maximum shut down Note Additional battery capacity is drawn during the automated rejuvenation process for firmware revisions 00 03 01 and greater Connector 2 way AMP 643226 1 female header Mates with AMP 350777 1 plug and AMP 350922 3 male terminals Pin out J2 1 Battery J2 2 Battery
27. In this configuration the battery should be primarily responsible for current surges in the system However the fuel cell system is able to handle current surges for short duration when it is warm Figure 28 illustrates the current surging capability of the Nexa system and is intended as a design guide for implementing battery load sharing with the fuel cell The fuel cell system will shut down if the stack current is detected to exceed the rated maximum of 70 amps for more than 50 milliseconds Figure 28 shows the recommended maximum fuel cell current as a function of duration to avoid shut downs due to other effects low cell voltages temperature etc Note that the latest firmware revision 00 03 01 increases the maximum stack current limit to 75A Refer to Section 7 2 for details regarding Nexa module warning and failure levels 80 70 60 50 40 20 Current Amperes 100 Time milliseconds 1000 10000 Figure 28 Maximum Fuel Cell Current as a function of Duration 3 2 05 Commercial Confidential 71 Nexa Power Module User s Manual MAN5100078 6 2 6 3 6 4 6 5 3 2 05 AN 6 Electrical Interface On Off Signal A hardwired signal is used to start and stop the fuel cell system as shown in the interface diagram A 5 V signal will start the fuel cell system and a 0 V signal will stop the fuel cell system The 5 V start signal must be held active to keep the fuel cell system turned on
28. Minimise static discharge Ground all equipment Residual reactants within the Nexa power module can develop a charge in a matter of minutes when turned off A reading of zero volts across the entire power module does not guarantee that all fuel cells are uncharged WARNING Always assume that the fuel cell stack is charged Jewellery such as rings necklaces bracelets and watches may concentrate an electric current when it comes into contact with charged components or when a shock passes through the human body Accordingly no jewellery should be worn near the power module WARNING Do not wear jewellery near the Nexa power module Commercial Confidential 27 Nexa Power Module User s Manual BALLARD MANS5 100078 3 5 3 6 3 7 3 2 05 High Temperature The fuel cell stack is designed to operate at 65 C At this operating temperature the air exhaust stream temperature can reach 55 C and the cooling air stream can reach 17 C above ambient conditions These temperatures are sufficient to cause burns or severe discomfort Accordingly avoid contact with the fuel cell stack or components that convey process or cooling air WARNING Avoid contact with the fuel cell stack or components that convey process or cooling air High Pressure Process air and hydrogen gas streams within the Nexa power module are regulated to low pressure These circuits do not pose a high pressure ha
29. Restartable Fuel Cell Stack Temperature gt 71 C gt 73 C Yes Fuel Cell Stack Voltage lt 23 Volts lt 18 Volts Yes Fuel Cell Stack Current gt 60 Amps gt 70 Amps Yes Firmware Revision 00 03 01 gt 65 Amps gt 75 Amps Yes Cell Voltage Checker N A 0 85 V cell pair Yes Hydrogen Pressure lt 1 0 barg lt 0 5 barg Yes Hydrogen Concentration 80 100 10 000 ppm No Oxygen Concentration lt 19 2 lt 18 7 Yes Ambient Temperature N A lt 3 start up Yes Battery Voltage N A lt 18 Volts start up Yes Purge Cell Voltage lt 1 0 Volts lt 0 8 Volts Yes Firmware Revision 00 03 01 lt 0 8 Volts 0 7 Volts Yes System Time out during Start up N A Digital Yes Self Test Fault N A Digital No Software Fault N A Digital No Table 14 Warning and Failure Alarm Limits Last Command Indicates the last serial RS 485 command received by the Nexa power module Self Test Fault If a Self Test Fault has occurred this field will indicate the kind of Self Test Fault that has happened S W Version Indicates the software version installed on the Nexa power module controller Purge Status Displays the status of the fuel purge control system Off On or Disabled and Open or Closed Resuscitation Shows the fuel cell resuscitation status Off or On and the total number of resuscitations Resuscitations are automatically initiated by the Nexa control system in response to low cell voltages and re
30. User s Manual MAN5100078 BAL 4 2 3 Main Screen The main screen of the NexaMon OEM software is illustrated in Figure 14 The main screen is the user interface through which all Nexa data monitoring logging diagnostics and system control functions are accessed A description of the software interface and basic functions is provided in this manual IE NexaMon DEM BALLARD E Stack Voll v dud ma 1900 95 0 NexaMon OEM 2 0 Curent Nexa 1 2 kw DC Fuel Pressure 1800 90 0 Fuel Cell Module Fuel Leak 1700 85 0 Control amp Monitoring Application RA Fuel Consumpt L 2002 1600 80 0 Oxygen Conc State STANDBY Air Temp C Failure NO FAILURE Purge Cell V mV Warning 1500 75 047 1400 70 0 Battery Volt V 1300 65 0 Air Flow sipm Air Pump 12V 3 V H2 Br Legs V Air Pump Fan Last Command NONE Stack Power W Seftest Faut LO T NORAIRE sio SA version i System Run Time Purge Status clam mm D System Life Time Resuscitation OFF Stack Start Time z Start Line Qj ec 500 25 0 Stack Stop Time i 400 20 0 Serial T O Chksum Err Stack Run Time Other Err details Stack Life Time OO 15 0 1200 60 0 1100 55 07 1000 50 0 900 45 0 800 40 0 700 35 0
31. Warning State is issued if any of the fuel cell system operating parameters fall outside of a desired range The Nexa module will still operate and produce power during a warning Refer to the Warning Status Field description for details Stopping If the start signal is removed the Nexa module goes through its normal shutdown procedure Hydrogen is vented from the fuel cell stack to remove water from the anode flow channels The air pump blows product water from the cathode side of the fuel cells for storage After the cathode air and cooling air supply are stopped and the hydrogen solenoid and purge valves are closed to isolate the stack Failure A Failure State is issued if any of the fuel cell system operating parameters fall outside of a permitted range If this occurs the Nexa module shuts down immediately The system remains in the Failure State until it is returned to Standby by removing the start signal Refer to the Failure Status Field description for details Non Restartable In most cases failures are resettable by removing the start signal returning the Nexa module to Standby mode and starting again However for safety reasons certain types of failures hydrogen leaks software faults amp self test faults are defined as Non Restartable If any of these faults occur the system is put into a Non Restartable State and cannot be restarted by simply toggling the start signal The Non Restartable State persists
32. and 2 the average stack power measured over the last 10 minutes of operation must exceed 200W 3 2 05 Commercial Confidential 10 Nexa Power Module User s Manual BALLARD MAN5 100078 2 1 3 2 05 Specifications Specifications for the Nexa power module are provided in this manual for reference only The specifications presented in this document do not supersede and in no way replace or substitute for the specifications that are attached to or referenced by a Sales Agreement with Ballard Power Systems Refer to your Sales Agreement for Product Specifications and Shipping and Storage Specifications for your Nexa modules Contact Ballard Customer Service if you have questions Product Specification Output specifications for the Nexa power module include power emissions physical characteristics and lifetime These specifications are attributes of the uninstalled Nexa power module and do not necessarily reflect the installed performance Required system inputs are also defined including fuel delivery battery input specifications and operating environment requirements Nexa specifications are subject to change Refer to the Ballard document Nexa Product Specification attached to your Sales Contract for the specifications of your Nexa modules The Nexa Product Specification is shown in Table 4 with definitions provided in Table 3 Performance and lifetime specifications are given along wi
33. board using a power supply or battery as illustrated in the previous section Establish communications between the Nexa module and computer by toggling the Communication Start Switch to the ONB position on the main screen The Nexa system should be in Standby State 4 Press on the Read EEPROM button F9 on the main screen The last fault data screen appears as shown in Figure 17 EEPROM Display 8 x 5 000 997 00 02 06 B LAST FAULT 1 LOW FUEL P 2 SELFTEST FAULT 3 LOW FUEL P 4 SELFTEST FAULT 5 LOW FUEL P 6 SELFTEST FAULT 7 LOW FUEL P 8 LOW FUEL P 9 SOFTWARE FAULT 10 LOW BATTERY V 11 LOW BATTERY 12 LOW BATTERY V 13 LOw BATTERY V 14 LOw BATTERY V 15 LOw BATTERY V 16 LOW BATTERY V 17 LOW FUEL P 18 LOW BATTERY V 19 LOW BATTERY 20 LOW BATTERY V E 8 8 _ 4 gt 2 8 7 8 PILIL PILIL Es 13 034 Figure 17 Sample of Last Fault Data Screen 3 2 05 Commercial Confidential 47 Nexa Power Module User s Manual 5100078 BAL 5 To view one of the 20 previous faults click on the desired fault on the fault list The header and sidebar items remain the same and the fault history shows the historical fault data as shown in Figure 18 This screen is similar to the last fault screen but only contains information pertaining to the selected faul
34. from the Nexa module 25 Pin male to 9 Pin female Serial Cable The serial cable is used to connect the RS485 to RS232 converter to the serial port of a laboratory computer Load Relay The load relay is connected to the positive output terminal of the Nexa module to prevent premature power draw The Nexa control board using the Communications Wiring Harness controls the load relay Nexa System Tray The system tray provides mounting posts for the module Hose A hose is provided to supply hydrogen to the Nexa module from a cylinder One end of the hose incorporates a 45 flared tube fitting which mates with the hydrogen connection of the Nexa unit see Interface Specifications The other end uses a 4 male NPT connection Always use Teflon tape when connecting adapters to NPT fittings Commercial Confidential 31 Nexa Power Module User s Manual MAN5100078 BALLARD N Installation e Nexamon OEM Software on CD ROM Labview software has been developed for providing basic monitoring and diagnostic functions An installation CD is provided Figure 7 illustrates the installation of a Nexa module in a laboratory setting In addition to the Installation Kit the following additional item are required to operate the Nexa module e Hydrogen Bottle Refer to Interface Specifications for hydrogen purity and consumption requirements e Pressure Regulator A pressure reg
35. from the Nexa power module it transitions to the NORMAL SHUT DOWN state Upon shut down the external load relay is opened to isolate the fuel cell stack from the load and the control board internally transfers parasitic loads from the fuel cell stack back to the external battery If the Nexa module has been sufficiently operated longer than 60 seconds it will also engage a shut down sequence that removes product water from the anode and cathode flow channels using the air pump and hydrogen purge valve The NORMAL SHUT DOWN sequence lasts 45 seconds Commercial Confidential 9 Nexa Power Module User s Manual 5100078 BAL 1 Introduction 1 10 Periodic Exercising The Nexa power module requires periodic exercising to maintain peak performance and to offset performance losses encountered during periods or prolonged storage or non operation Fuel cell performance loss is characterised by reduced output voltage or reduced power output capacity Performance gradually declines with increasing storage duration with an expected floor of approximately 10 degradation in one year Elevated storage temperatures accelerate the rate of performance loss In extreme cases the Nexa power module may not be able to start because start up permissive values cannot be achieved Storage loss affects are fully reversible through operation Running Nexa power module continually will recover any loss in performance d
36. fuel cell stack in order to sustain the fuel cell reaction An intake filter protects the compressor and downstream components from particulate in the surrounding air The compressor speed is adjusted to suit the current demand of the fuel cell stack Larger currents require more airflow A downstream sensor measures air mass flow rate and controls fine tune the compressor speed to suit the required current demand Oxidant air is humidified before reaching the fuel cells to maintain membrane saturation and prolong fuel cell lifetime A humidity exchanger transfers both fuel cell product water and heat from the wet cathode outlet to the dry incoming air Excess product water is discharged from the system as both liquid and vapour in the oxidant air exhaust Product water must be managed through end use integration design Excess water may be evaporated passively into the surrounding environment as shown in Figure 2 Alternatively product water can be drained and collected 1 6 Cooling System The Nexa fuel cell stack is air cooled A cooling fan located at the base of the unit blows air through vertical cooling channels in the fuel cell stack The fuel cell operating temperature 1s maintained at 65 C by varying the speed of the cooling fan The fuel cell stack temperature is measured at the cathode air exhaust as shown in Figure 2 Hot air from the cooling system may be used for thermal integration purposes Heat rejected in the air can be
37. guide provides detailed purity specifications for the fuel supply and allowable contaminant levels to ensure proper Nexa system performance and lifetime Refer to NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 The air quality surrounding the Nexa module must also be considered when packaging transporting storing or operating the unit Table 19 provides a list of known contaminants that could reduce output performance or system lifetime 1f ingested by the fuel cell through its air intake Common sources for these contaminants are provided along with the degree of concern and concentration limits when known Operating the Nexa module in the presence of combustion exhaust is one mechanism for fuel cell contamination Nitric oxide and or sulphur dioxide in the air can block catalytic sites and reduce fuel cell output performance However in most cases the performance loss due to combustion exhaust gases is fully recoverable through operation in fresh air General purpose cleaners paint strippers dyes paints and other chemicals can also lead to fuel cell contamination In some cases these chemicals irreversibly absorb on
38. hydrogen gas cylinders without training or experience e Use a pressure regulator to control the fuel inlet pressure to the Nexa system e Do not alter the fitting on a regulator Ask experienced personnel for help e Do not attempt to force gas cylinder threads e Never transport a gas cylinder with regulators attached Ensure cylinder caps in place Always use a cylinder cart with a safety strap or chain e Secure a high pressure cylinder to a bench post or fixed object to avoid accidental contact e Avoid unnecessary contact with On Off valves They can easily move to by accident Hydrogen Leakage Hydrogen is colourless odourless and tasteless Hydrogen is non toxic but can act as a simple asphyxiant by displacing the oxygen in the air There are no warning symptoms before unconsciousness results WARNING Inhaling hydrogen can lead to unconsciousness and asphyxiation Hydrogen molecules are smaller than any other gas making hydrogen more difficult to contain It can diffuse through many materials considered airtight Fuel lines non welded connections and non metal seals such as gaskets O rings pipe thread compounds and packings present potential leakage or permeation sites Furthermore hydrogen s small molecule size results in high buoyancy and diffusivity so leaked hydrogen will rise and become diluted quickly Constant exposure to hydrogen causes hydrogen embrittlement in many materials The
39. illustrates the electrical interface and required electrical connections for the Nexa power module External battery power must be supplied to the DC module for providing ancillary power during startup and shut down The battery is connected to the Nexa control board through a switch as shown in Figure 27 to prevent the battery from being drained during non operational periods The fuel cell terminals must be connected to load through a load relay to ensure power is not drawn from the fuel cell stack until the system 1s running The Nexa control board actuates the load relay when the stack is ready to supply power An external 5 V start signal must be applied as shown in Figure 27 to turn on the unit A serial communication interface must also be provided to read performance and diagnostic data sent from the Nexa control board Finally an external hydrogen tank valve control line is supplied to energize a fuel isolation valve at the OEM storage tank The communication and battery interface connections to the Nexa control board are shown in Figure 22 Nexa Fuel Cell System Integrated OEM System Battery Control vA J2 2 Battery Battery 22 1 Fuel Cell TEI Power VU 48 AWG 14 8 NS 3 Control 487 Signal V Start Signal 5V ON 1 OFF 1 Cable 16 Conductors 18 AWG J4 B16 Serial Interface Tx i J4 B15 24 14 E Rx un L O E Com 2 Com Hyd
40. of about 10 The Nexa module firmware revisions 00 03 01 or greater incorporates an automated rejuvenation process which corrects for storage losses and recovers system performance upon shutdown To maintain peak performance it is recommended that customers exercise their Nexa modules every 2 3 months to initiate this rejuvenation process Refer to Section 7 1 6 1 for details on the rejuvenation process The Nexa module can be frozen so long as it is thawed before its next operation The onboard controller does not permit start up if it detects the stack is still frozen The lifetime and performance impacts of up to 50 freeze thaw cycles have been evaluated as shown in Table 26 The system output voltage degrades at a rate of about 23 mV cycle or 1 1V after 50 freeze thaw cycles are executed The affect of additional freeze thaw cycles on output performance has not been evaluated at this time The information presented in this section is considered typical for Nexa power modules and should be used as a guide for developing system integration design concepts Contact Ballard Customer Service for more detailed information and design guidelines 3 2 05 Commercial Confidential 100 Ment User s Manual BALLARD 10 10 1 10 2 10 3 11 3 2 05 1 Planned Planned Maintenance Component Action Frequency Nexa power module Exercise Rejuvenate 2 3 Months Air Filter Replace 500 Ho
41. stream and diluted before it exits the Nexa system boundary Water entrained in the hydrogen purge stream is evaporated into the cooling air and dismissed into the surrounding environment Always ensure that the cooling air is ducted over the Nexa hydrogen leak detector to ensure safe dilution levels are maintained in the exhausted air stream The Nexa system will shut down automatically if the leak detector reading reaches 10 000 ppm which is 1 4 of the lower flammability limit LFL of hydrogen Commercial Confidential 58 Nexa Power Module User s Manual BAL 2n MAN5 100078 an 5 Mechanical Interface Under normal operation the Nexa fuel cell stack will leak a small amount of hydrogen externally to its surrounding environment NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 indicates the anticipated stack external leak rate at beginning of life BOL and end of life EOL Damage to the fuel cell stack such as a fractured plate can lead to external leak rates many times greater than normal During the integration design phase it is important to ensure that the fuel cell compartment is properly
42. supply to the fuel cell stack The valve fails closed so that the fuel supply is immediately removed in the event of a system failure An external solenoid valve is also recommended for isolating hydrogen supply at the source The Nexa system provides a control signal for the proposed secondary fuel solenoid so that both fuel isolation valves may be controlled in tandem Refer to the Electrical Interface Specifications for control signal details 3 2 05 Commercial Confidential 59 Nexa Power Module User s Manual 5100078 BALLARD 53 3 2 05 5 Mechanical Interface Oxidant Air Interface Oxidant air inlet and outlet interface specifications are provided in Table 17 The Nexa system consumes oxygen from the ambient air for producing electrical power The maximum air consumption rate is approximately 90 slpm at rated power For protection against oxygen depletion always operate the Nexa power module in a well ventilated area For additional safety the system is equipped with an oxygen sensor Refer to the Software and Communication Interface for alarm and shut down details Figure 23 illustrates the oxidant air inlet to the Nexa system A removable air filter is located at the inlet to the air pump assembly The filter is installed to catch particles down to the 10 micron level in the air before they get into the process air pump Additional air filtration is not required Periodic replacement of the air f
43. the Communications Wiring Harness as shown in the figure Ensure that the load relay is functioning properly before applying load to the module Confirm that the relay is open when the Nexa module is Off or in Standby and that it closes only when the unit is Running Ne mmm Figure 12 Installing the Load Relay Connecting the Hydrogen Supply Figure 13 illustrates the hydrogen supply connection to the Nexa module Figure 13 Connecting the Hydrogen Supply Commercial Confidential 35 Nexa Power Module User s Manual 5100078 BAL Installation 4 2 4 2 1 4 2 2 3 2 05 NexaMon OEM Software The Installation Kit comes equipped with a LABVIEW software program which provides a graphical user interface to the Nexa module s operational status and performance The software program is not needed to operate the Nexa module However it provides basic data monitoring logging and diagnostic features that can be very helpful when conducting a fuel cell testing program in the lab The features and capabilities are described in this manual Hardware Requirements The following computer and hardware requirements must be followed to run the NexaMon OEM software program e Pentium computer with Windows 95 or later a minimum of 166 MHz clock speed 64 Mb of RAM and a screen resolution of 1024 x 768 pixels The computer must come equipped with at least one serial port 9 pin male for
44. the catalyst and cause permanent damage In others the affect is reversible through operation Refer to Table 19 Commercial Confidential 63 Nexa Power Module User s Manual MAN5100078 an 5 Mechanical Interface A list of industrial and household products containing substances that may cause contamination to the fuel cell stack can never be exhaustive Given that the Nexa unit does not require an external water supply and is to use only fuel meeting Ballard Power Systems specifications the sole path for the ingestion of contaminants is its requirement to draw air from the surrounding local atmosphere Many of the contaminants in the following list are contained in various products used in industry and around the home However if an airborne form does not exist there will be no method of delivery and the fuel cell will not become contaminated When the unit is not operating a closed environment should be maintained to prevent airborne contamination Harmful Compounds Substances Common Products or Devices in which compounds substances can be found Degree of Concern Fossil Fuel Combustion B y Products Nitric Oxide Sulphur Dioxide Operation of indoor gas heaters fireplaces wood burning heaters and internal combustion engines Tobacco smoke and incense also produce these compounds Concern High 1 ppm Nitric Oxide 10 ppm Sulphur Dioxide Halogenated Organic Compounds
45. ventilated and monitored to ensure that explosive gas mixtures are not formed LFL 10 000 ppm should be used as the maximum tolerable hydrogen gas concentration within the fuel cell compartment It is advised that the Nexa cooling fan intake be used to ventilate the surrounding fuel cell enclosure In this way the Nexa hydrogen leak detector situated in the cooling air exhaust can also be used to monitor for unsafe gas compositions within the enclosure Alternatively the OEM integrator may incorporate a separate compartment ventilation fan and hydrogen leak detector within his packaging design The OEM is responsible for ensuring adequate ventilation and hydrogen leak detection is incorporated into their packaging design The Nexa fuel cell stack is equipped with a pressure relief valve NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 provides specifications for the valve In the event of a stack over pressure condition the relief valve discharges into the vicinity of the hydrogen leak detector refer to Figure 23 and the unit is shut down The Nexa power module incorporates a solenoid valve for isolating hydrogen
46. you are close to an exposed fuel cell stack e Minimise static discharge If possible ground all equipment Commercial Confidential 26 Nexa Power Module User s Manual 5100078 BAL 3 2 05 e Minimise conductivity Avoid contact with surfaces that in contact with water gases Do not operate or store in wet or damp conditions e Use a three wire grounding plug when connecting electrical devices e Never use damaged extension cords The Nexa power module generates up to 50 VDC open circuit voltage This voltage decreases as current is drawn from the module The Nexa power module produces 26V at maximum power This voltage is exposed at the output power connections These low voltages may constitute a shock hazard and can damage electronic components if shorted Therefore do not touch individual fuel cells cell voltage monitoring equipment or electrical components WARNING Do not touch fuel cells cell voltage monitoring equipment or electrical components Electronic components can also be damaged as the result of static discharge To minimise this ground all equipment in contact with the power module Use a three wire grounding plug when connecting external loads Never use damaged extension cords Minimise conductivity by avoiding surfaces in contact with water hands and clothes must be dry Do not operate or store the power module in wet or damp conditions WARNING
47. 078 Installation 4 2 4 3 2 05 Status Fields The Nexa Status Fields located in the upper left hand corner of the Main Screen indicate the operating state of the power module warning and failure codes as well as control system settings during operation description of each field is provided State Field Indicates the current operating state of the power module which may include any one of the following system states Standby The Nexa system is in Standby when power is being supplied to the control board from an external power supply or battery but a start signal has not been applied Starting When a start signal is applied the Nexa system enters the Starting State The cooling fan and the air pump are started and the solenoid valve isolating fuel supply is opened to create stack voltage During the start up sequence stack performance sensor readings and operating conditions are monitored and evaluated against permissive criteria to determine if the system is capable of running If any of the start up criteria are not met during the Starting sequence the system fails Start Time Expired and flags the Nexa State Field accordingly Running After the start up criteria are met Nexa power module enters the Running State and power may be drawn from the unit At this point the Nexa controller closes the external relay that connects the fuel cell module to load Warning A
48. 19 5 lt 18 7 Yes Ambient Temperature N A lt 3 C start up Yes Battery Voltage N A lt 18 Volts start up Yes Purge Cell Voltage lt 1 0 Volts lt 0 8 Volts Yes Firmware Revision 00 03 01 lt 0 8 Volts 0 7 Volts Yes System Time out during Start up N A Digital Yes Self Test Fault N A Digital No Software Fault N A Digital No Table 25 Warning and Failure Alarm Limits A few notes about alarm conditions e Fuel cell stack current alarms refer to the gross output of the stack not the net output of Nexa Refer to the Performance Characteristics section for output performance details e The hydrogen failure alarm is set to 10 000 ppm or 1 which is of the lower flammability limit of hydrogen The hydrogen concentration reading is expressed as a percentage of this shut down limit e Low battery voltage and low ambient temperature alarms are effective only during system start up Once the Nexa system is running the OEM integrator is responsible for shutting down the power module and balance of plant in the event of an undesirable battery voltage or ambient temperature environment After a failure shut down the Nexa system can be returned to Standby mode by removing the start command In most cases the system is Restartable after a shut down However when a hydrogen leak or a self test fault leads to a failure shutdown the Nexa unit will 3 2 05 Commercial Confidential 79 5100078
49. 5 FIGURE 25 TOP VIEW OF THE POWER MODULE csscesssessesseessecssecssecsecceseseesseesscesscesscsaeessecssecseccsesesteesseseess 56 FIGURE 26 FRONT AND BACK VIEWS OF THE NEXA POWER MODULE eene nennen eene nnne ens 56 FIGURE 27 ELECTRICAL INTERFACE DIAGRAM earn nns 69 FIGURE 28 MAXIMUM FUEL CELL CURRENT AS A FUNCTION OF DURATION cccessessececececsenssaececececeesssaeceeeceesensaaees 71 FIGURE 29 GROUNDING OF POWER LEADS cssssssecsssseeesssececesaececseseececsneeecsesaececeesaeseeseeeessesuececeeaeesesueeessesaeescneaaees 73 FIGURE 30 GROUNDING OF COMMUNICATIONS 74 FIGURE 32 OPERATING STATES nni eee tee ree debe Pee eed eee eet e Tete repo ce ede ee eee tete cabe cero eren 75 FIGURE 33 POLARIZATION AND POWER CURVEG s ccsssssssessesceseeseeecseaaececeaeeeceesaeeecsesaececseseessesueeecseaaeeecseseeeeesseeeseagas 91 FIGURE 34 HYDROGEN CONSUMPTION RATES 92 FIGURE 35 NET SYSTEM EFFICIENCY CURVE seerias de eee E YE Pe a e epe RE Ee Fe a vere SEE e 93 FIGURE 36 HEAT PRODUCTION RATES ccccsssssecssssssecssseecsessssecseseesecsesaeesssssecsessesecseasecesessecseseusecsecaeessessecsesansecesaes 94 FIGURE 37 WATER PRODUCTION RATES
50. 9 0x42 in that order 14 The engineering units for the data are as follows Data Name Engineering Unit Fuel Cell Stack Temperature Fuel Cell Stack Voltage volts Fuel Cell Stack Current amps Hydrogen Pressure bar gauge Hydrogen Concentration ppm Cumulative Hydrogen standard litres Consumption Oxygen Concentration percent Ambient Temperature AC Purge Cell Voltage volts 15 Messages from the OEM to the Nexa control board are always 5 bytes long The format for the message is given below Tag Command Failure Acknowledge Check Sum Tag 16 All of the information in the OEM command will be single bytes with the check sum computed in the same fashion as above 3 2 05 Commercial Confidential 82 Nexa Power Module User s Manual BAL 2n AN51 5100078 7 Software and Communications 7 3 1 3 2 05 17 The commands needed by the Nexa system are developed for customer specific diagnostic and field service functions 18 The Failure Acknowledge will be a repetition of the last Fail Code received from the control board Notes on Slip Decoding In Normal Mode the Nexa system transmits a 40 character status message followed by a 1 byte checksum If the status data contains the SLIP End Character 0xCO or the SLIP Escape Character OxDB then each occurrence of these characters is encoded as a two byte escape sequen
51. B3 External output tank solenoid valve J4 B4 External output tank solenoid valve J4 B5 External input on off signal J4 B6 External input on off signal J4 B7 External output load contactor J4 B8 External output load contactor J4 B9 Reserved J4 B10 Reserved J4 B11 Ground J4 B12 Communications common J4 B13 Communications receive J4 B14 Communications receive J4 B15 Communications transmit J4 B16 Communications transmit Commercial Confidential 21 Nexa Power Module User s Manual 5100078 BAL XL Table 13 Communications Connector 3 2 05 Commercial Confidential 22 Nexa Power Module User s Manual BALLARD MANS5 100078 3 1 3 2 3 2 05 Safety NOTE The safety guidelines included here may not cover every situation Use common sense General Information For this unit to generate electrical power a supply of hydrogen fuel is necessary It is important for any operator to be aware of understand and follow all local safety requirements related to the handling of hydrogen and compressed gases Ensure that your facility conforms to all local regulatory requirements including building codes and recommendations The fuel cell system has built in safeguards and is designed to shut down automatically if any out of range operating condition occurs Possible situations include low cell voltage high current high temperat
52. BY state pe CON Ue When a fault is detected fuel cell will follow a System Shutdown Procedure and enter a Failure Shut Down mode The fuel cell system cannot be re started from this state until the start line 1s turned off or battery power is cycled to the control board Note Do not cycle the battery power to the Nexa module faster than once every 5 seconds Commercial Confidential 78 Nexa Power Module User s Manual BAL 2n an 7 Software and Communications 5100078 7 2 Warning amp Failure Levels Table 25 shows the warning and failure levels used by the fuel cell system If a failure level is exceeded during operation the system executes a failure shut down If a warning level is exceeded the system may continue operating but the OEM integrator should take corrective action to remove the alarm condition Note that the latest firmware revision 00 03 01 incorporates some changes to the warning and alarm limits Parameter Warning Level Failure Level Restartable Fuel Cell Stack Temperature gt 71 C gt 73 C Yes Fuel Cell Stack Voltage lt 23 Volts lt 18 Volts Yes Fuel Cell Stack Current gt 60 Amps gt 70 Amps Yes Firmware Revision 00 03 01 gt 65 Amps gt 75 Amps Yes Cell Voltage Checker N A 0 85 V cell pair Yes Hydrogen Pressure lt 1 0 barg lt 0 5 barg Yes Hydrogen Concentration 80 100 10 000 ppm No Oxygen Concentration lt
53. E PRODUCT WATER CONTAMINANTS Commercial Confidential ARU Nexa Power Module H lt SF gt E p ee HD We N b2 b2 b2 b2 b2 P2 P2 oo ON W N N Ww ar gt tA tA Nexa Power Module User s Manual BAL ARL MAN5100078 Nexa Power Module 5 7 MATERIAL COMPATIBILITY 65 6 ELECTRICAL INTERFACE 69 6 1 POWER CONNECTION 70 6 2 ON OFF SIGNAL 72 6 3 SERIAL INTERFACE 72 6 4 HYDROGEN TANK VALVE CONTROL 72 6 5 INTERFACE CONNECTORS 72 6 6 GROUNDING 73 7 SOFTWARE AND COMMUNICATIONS 75 7 1 OPERATING STATES 75 7 2 WARNING amp FAILURE LEVELS 79 7 3 COMMUNICATIONS 80 8 PRODUCT INTEGRATION 86 8 1 PACKAGING amp ENCLOSURE DESIGN 86 8 2 ELECTRO MAGNETIC INTERFERENCE 86 8 3 SHOCK amp VIBRATION 86 8 4 DESIGN FOR MAINTENANCE 87 8 5 CERTIFICATION REQUIREMENTS 88 9 PERFORMANCE CHARACTERISTICS 90 9 1 POLARIZATION CHARACTERISTICS 90 9 2 HYDROGEN CONSUMPTION 92 9 3 EFFICIENCY 93 9 4 HEAT PRODUCTION 94 9 5 WATER PRODUCTION 95 9 6 NOISE EMISSIONS 96 9 7 TRANSIENT RESPONSE CHARACTERISTICS 97 9 8 POWER DE RATING CURVES 98 9 9 LIFETIME amp DEGRADATION CHARACTERISTICS 99 10 PLANNED MAINTENANCE 101 10 1 EXERCISE REJUVENATION 101 10 2 AIR FILTER 101 10 3 HuMiDITY EXCHANGER 101 11 TROUBLE SHOOTING 101 11 1 WARNING amp FAILURE LEVELS 101 11 2 NON RESTARTABLE FAULTS 102
54. GGING COMMUNICATION eS Period Log On 4 Temp Log File csv mo A n 0 02s 2s 10s 0s 10m EO Start On F12 Figure 15 Configuring a Data Log File 3 NOTE The power module sensors are used for system control and safety and may not provide accurate performance data When possible use calibrated external sensors to measure 3 2 05 system data The data logging files contain all of the information displayed on the Main Screen of NexaMon OEM as illustrated in Figure 14 The data logging files also contain additional internal signal data for Ballard Power Systems use only Each parameter and its associated unit of measure is detailed in Table 15 Commercial Confidential 42 Nexa Power Module User s Manual MAN5100078 Installation Parameter Units Time MS Excel Time Format The number of days since Jan 1 1900 State Code a k a status 0 Standby 1 Starting 2 Running 3 Warning 4 Stopping 5 Failing 6 Non Restartable Failure Code a k a Failure status 0 Normal Operation 1 High Fuel Cell Stack Temperature 2 Low Fuel Cell Stack Voltage 3 High Fuel Cell Stack Current 4 Low Cell Voltage 5 Low Fuel Pressure 6 Fuel Leak Detected 7 Low Oxygen Concentration 8 Low Ambient Temperature 9 Low Purge Cell Voltage 10 Low Battery Voltage 11 Startup Time Expired 12 Self
55. If not put the character in the receive buffer If so and the receive buffer is empty continue Otherwise invoke the SLIP decode routine on the contents of the receive buffer 2 Ifthe SLIP decode routine returns 0 then the decode operation failed This will only happen if there was noise on the serial line and a byte stuffed SLIP character was dropped from the message 3 Ifthe SLIP decode routine returns a non zero value N then the first N 1 characters constitute the Nexa status message and the Nth character is the 8 bit checksum over the preceding N 1 characters Compute the checksum over the first N 1 characters and compare it to the Nth octet If they match then the N 1 char status messages has been received intact If not discard the message Strictly speaking a packet that conforms to the SLIP protocol need only have the trailing 0 It is standard practice however to prefix a SLIP encoded message with a leading OxCO The purpose of this is to flush a partially received message from the receiver s buffer i e a message whose tail including its trailing 0xCO was corrupted or truncated due to noise on the serial line The leading 0xC0 of the next message will cause the partially received data of the previous message to be flushed out of the receive buffer and be passed to the SLIP decode routine The SLIP decode operation may or may not succeed Regardless integrity of a Nexa message 15 protected by its checksum If the c
56. Installation Kit can be provided as part of the purchase The kit provides interface hardware to enable quick and easy installation in the test lab Labview software is also provided as part of the installation Kit which provides basic monitoring and logging and features 3 2 05 Commercial Confidential 30 Nexa Power Module User s Manual MAN5100078 BAL Installation 4 1 3 2 05 Installation Kit The Installation Kit is illustrated in Figure 6 It contains the following equipment to enable quick and easy installation of the Nexa module into a test lab 6 24 2002 Figure 6 Nexa Installation Kit Communications Wiring Harness The communications wiring harness provides several functions It is used to connect the Nexa control board to a 24 V power supply for providing standby and start up power to sensors and other onboard components It is also used to send serial information from the Nexa module to a laboratory computer for monitoring and diagnostic purposes The cable connects to the RS485 communications port of the Nexa control board and provides an RS485 to RS232 converter for interfacing with a computer s serial port In addition the harness includes a start switch which applies a 5 V start signal to the control board to start the module Finally the harness includes a load relay control cable which connects the control board to an external load relay for engaging and disengaging loads
57. Nexa output conditions are 26 VDC at 46 A Refer to the Performance Characteristics section for detailed polarisation curves When integrating power conditioning equipment with the DC module it is recommended that all sparking and arcing components are separated from the hydrogen containing environment of the fuel cell compartment The maximum current ripple specification for the Nexa unit is 24 7 RMS or 35 peak to peak at a switching frequency of 120 Hz Ensure that the fuel cell current ripple induced by power conditioning equipment does not exceed this specification Battery Connection Connect the battery to the fuel cell system as shown in Figure 27 It is recommended that the battery should be installed such that all spark emitting components are in a separate chamber from the fuel cell The Nexa control board uses an AMP 643226 1 connector To interface to the control board use an AMP 350777 1 plug and male terminal AMP 350922 3 The fuel cell system will operate with a battery voltage between 18 and 30 volts The battery should be disconnected when the OEM system is unplugged and non operational or is in long term storage to prevent battery depletion As battery power is applied to the control board the controller begins its initialisation sequence The battery power should not be removed during this sequence as it will cause a microprocessor fault on the subsequent start up As a rule the power to the control board shoul
58. ONNECTION ii dra Ee deer vade PROCESS AIR QUTLET CONNECTION e Genet ete one Cet aped t queue Fee ea ane aes COOLING AIR INLET CONNECTION COOLING AIR OUTLET CONNECTION OUTPUT POWER CONNECTION O dedil ete e ce EE eade do t ce e eo P denen BATTERY INPUT CONNECTION 2 et cce eter tt te toD ede CR eet Ras WARNING AND FAILURE ALARM LIMITS ient nennen ene eth nnns seen eterne nnns seen tete NEXAMON OEM DATA LOGGING FORMAT eese HYDROGEN INTERFACE SPECIFICATIONS cccccccccssssssececccecsesssececececsessasececececeesesececeeecsessaeaeteceeseseaeaeeeeecs OXIDANT AIR INLET AND OUTLET INTERFACE SPECIFICATIONS eese enemies 61 COOLING AIR EXHAUST SPECIFICATIONS eee LIST OF CONTAMINANTS AND COMMON SOURCES KNOWN INCOMPATIBLE MATERIALS niaii siiis in a e ia E EE E POWER LOAD RELAY SPECIFICATIONS e E E E E E ie nnn EXPECTED POWER DRAW REQUIREMENTS FROM THE BATTERY eee n emen enne eene 71 HYDROGEN STORAGE TANK VALVE INTERFACE SPECIFICATIONS eese nennen ennt 72 ELECTRICAL INTERFACE CONNECTORS wi cs s5c0isecedeessescecesdeccdcescedsucsscecedcvsseduescadacdsscncedesiedcucdeesteadenceadediteess 72 WARNING AND FAILURE ALARM LIMITS
59. Restartable button is used to reset non restartable faults in the Nexa module If executed the user will be prompted to verify that the source of the fault has been addressed before continuing For instance if the onboard sensor detects a hydrogen leak the power module will be automatically shut down and placed in a Non Restartable State If the user attempts to clear that fault using the NexaMon OEM software he will be prompted to check that the source of leak has been removed before continuing as illustrated in Figure 20 Figure 20 Resetting Non Restartable Faults If you experience a Non Restartable Fault with your Nexa module and are unsure of the cause contact Ballard Customer Service for further guidance Air Pump and Cooling Fan Diagnostic tools are included to test the air pump and cooling fan separately The Start button turns on the pump or the fan according to a preset speed The Stop button turns off the device Use the slider bars to adjust the speed of the fan or the pump or alternatively type in the speed setting ranging from 0 to 100 Note that running the air pump when the Nexa module is not in operation can cause drying of the fuel cell membranes and reduced system lifetime When conducting an air pump diagnostic test minimise the amount of time that the air pump is left running Commercial Confidential 52 Nexa Power Module User s Manual BAL 5100078 Installation
60. TE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 also indicates the required hydrogen purity and allowable contaminant levels for the fuel supply Adhere to the fuel composition specification to ensure proper Nexa system performance Requirement Description Quantity Fuel type Gaseous hydrogen Fuel composition 99 99 H2 Dry 99 99 Fuel humidification Dry gas None required Fuel inlet supply pressure Allowable range of fuel inlet supply pressure 70 1720 kPa g 10 250 psig Fuel inlet supply temperature Allowable range of fuel inlet supply temperatures 5 C 80 5 C 80 Pressure relief valve Hydrogen pressure relief valve setting 2400 kPa g 350 psig Acceptable impurities Inert gases He Ar N2 water vapour 0 01 power during anode purging Hydrocarbons lt 1 ppm Oxygen 500 ppm CO and CO2 combined 2 ppm Sulphur compounds lt 1 ppm Ammonia 0 01 ppm H2 fuel connection 45 flared tube fitting male for 1 4 OD 1 4 OD tubing H fuel consumption H2 fuel consumption at maximum power lt 18 5 slpm
61. Test Fault 13 Software Fault Warning Code a k a Warning status 1 byte additive 0 No Warnings 1 High Fuel Cell Stack Temp Warning 2 Low Fuel Cell Stack Voltage Warning 4 High Fuel Cell Stack Current Warning 8 Low Fuel Pressure Warning 16 Fuel Leak Warning 32 Low Oxygen Concentration Warning 64 Low Purge Cell Voltage Warning Last Command Ballard use only Stack Air Exhaust Temperature C Stack Voltage V Stack Current A gross Fuel Pressure barg Fuel Leak Hydrogen Concentration Alarm 10096 196 H2 Fuel Consumption L Oxygen Concentration 926 Air Ambient Temperature C Purge Cell Voltage V Battery Voltage VDC Process Air Flow SLPM Air Pump 12 3 Operating Voltage VDC 3 2 05 Commercial Confidential 43 Nexa Power Module User s Manual BAL 2n 5100078 Installation Hydrogen Sensor Bridge Voltage VDC Process Air Pump Duty Cycle Cooling Air Fan Duty Cycle Port A to Port F Ballard use only Stack Voltage ADC analog to digital Ballard use only conversion Stack Current ADC Ballard use only Fuel Pressure ADC Ballard use only Purge Cell ADC Ballard use only Stack Temperature ADC Ballard use only Oxygen Percentage ADC Ballard use only Air Flow ADC Ballard use only Ambient Temperature ADC Ballard use only
62. accept operational commands for self test and diagnostic purposes Unusual or unsafe operating conditions result in either a warning or alarm and automatic shutdown depending on severity During a warning the Nexa power module continues to operate and the controller attempts to remedy the condition During an alarm the controller initiates a controlled shutdown sequence Removing the external on off signal will reset most alarms Once reset the Nexa power module can then be restarted For safety reasons cer tain alarms can only be reset by Ballard Customer Service These non restartable faults include hydrogen leaks self test faults and software faults When energised the controller continually transmits data approximately once every 200 ms Transmitted data includes system status codes warning codes and alarm codes as indicated in Table 1 In addition fuel cell system operating parameters are transmitted for monitoring and display purposes The data 1s displayed in engineering units for selected transducers as indicated in Table 2 Commercial Confidential 6 Nexa Power Module User s Manual 5100078 BAL XL Status Codes Warning Codes Alarm Failure Codes Standby No Warnings Normal Operation Starting High Fuel Cell Stack Temperature Warning High Fuel Cell Stack Temperature Running Low Fuel Cell Stack Voltage Warning Low Fuel Cell Stack Voltage Warning High Fuel Cell Stack Current Warning High Fuel C
63. are checked The monitored process variables are Stack Temperature Stack Voltage Stack Gross Current including parasitic loads internal to the power module Fuel Pressure entering the power module upstream of the inlet pressure regulator Percentage of Fuel Leak Alarm where 100 indicates 10 000 ppm or 25 LFL of hydrogen in air Fuel Consumption relative to start of run Oxygen Concentration in the ambient air as measured in the vicinity of the controller Ambient Air Temperature as measured in the vicinity of the controller Purge Cell Voltage Battery Voltage used to start the power module Process Air Flow as measured by the mass flow meter Air Pump Operating Voltage Hydrogen Concentration Bridge Voltage Process Air Pump Duty Cycle Cooling Air Fan Duty Cycle Stack Gross Power calculated from current and voltage measurements Air Flow Stoichiometry calculated from the air mass flow and the current draw Commercial Confidential 40 Nexa Power Module User s Manual 5100078 BAL Installation 4 2 7 4 2 8 3 2 05 Chart The chart plots the progress of the checked process variables The chart line colour for each process variable is shown beside the process variable name Turn the process variable chart lines on or off by clicking on the check box beside the variable s name The check box state does not affect the information that 1s logged to disk The X axis represents time in
64. are satisfied e Ensure that the Nexa system is installed in a well ventilated lab area equipped with hydrogen alarm sensors Alternatively install the Nexa unit underneath a fume hood e Ensure the air quality of the test lab is sufficient for fuel cell operation For example do not operate the Nexa system adjacent to gasoline generators or in a non ventilated room hydrogen tank 0 7 17 barg 5V start stop signal control line 13 6 V 500 mA 486 232 ocrial communication uolunoid vulve display diode load plun es BALLARD Figure 5 Installation of the Nexa power module 3 2 05 Commercial Confidential 29 Nexa Power Module User s Manual 5100078 BAL Follow the provided instructions to establish a laboratory test station for the Nexa power module e Install the Nexa power module onto a stand using the mounting feet as shown in Figure 5 e Provide a suitable supply of hydrogen Connect the fuel supply to the hydrogen connection as shown in Figure 5 Refer to the Interface Specifications for detailed fuel purity and connector specifications e Connect a 24 VDC battery to the Nexa control board as shown in Figure 5 Alternatively you may use a 24 VDC power supply Ensure the power supply is capable of at least 6 amps to support current surges on system start up Refer to the Interface Specifications for detailed installation and connector specification
65. at a higher pressure than the minimum supply pressure see Table 25 for warning and shut down values Table 6 also indicates the required hydrogen purity and allowable contaminant levels for the fuel supply Adhere to the fuel composition specification to ensure proper Nexa system performance Description Specification Composition 99 99 hydrogen lt 0 01 Maximum total inert fluids He No Ar and water vapour lt 2 ppm carbon dioxide carbon monoxide lt 500 ppm oxygen lt 1 ppm sulphur compounds lt 1 ppm hydrocarbons Pressure 70 to 1720 kPa g Temperature 5 to 80 C Flow lt 18 5 slpm at maximum power Pressure Relief Valve Setting 2400 kPa g Connection 45 flared tube fitting male for 1 4 OD tubing NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 25 for warning and shut down values Table 6 Hydrogen Inlet Connection Commercial Confidential Nexa Power Module User s Manual MAN5100078 An 2 3 2 Process Air Inlet The process air inlet draws air from the ambient surroundings for use in the fuel cell power reaction Specifications for the process air inlet connection are prov
66. ave the potential to burn or explode Leaked hydrogen can concentrate in an enclosed environment thereby increasing the risk of combustion and explosion Hydrogen flames are pale blue and are almost invisible in daylight due to the absence of soot Due to its high buoyancy and diffusivity burning hydrogen rises unlike gasoline which spreads laterally A flammable or explosive hydrogen mixture is easily ignited by a spark or even a hot surface The auto ignition temperature of hydrogen is 500 C 932 F The energy ofa hydrogen gas explosion is 2 4 times that of gasoline or methane for an equal volume Hydrogen gas explosions are therefore more destructive and carry further WARNING A mixture of hydrogen and air is potentially flammable and explosive and can be ignited by a spark or a hot surface As in the presence of any fuel all sources of ignition including smoking are not permitted in the vicinity of the power module WARNING Keep all sources of ignition away Smoking is not permitted in the vicinity of the Nexa power module Commercial Confidential 25 Nexa Power Module User s Manual BALLARD MANS5 100078 3 3 3 4 3 2 05 Oxygen Depletion Oxygen is a colourless odourless non toxic and tasteless gas Oxygen is essential for life in appropriate concentrations Ambient air contains up to 21 oxygen Oxygen levels below 19 5 are biologically inactive and may act as simple asphyx
67. board using the Communications Wiring Harness 6 24 2002 Figure 9 Connecting the 24V Power Supply 3 2 05 Commercial Confidential 33 Nexa Power Module User s Manual MAN5100078 BALLARD 4 1 3 3 2 05 Connecting the Communications Port The Nexa communications port provides the interface for all external equipment Serial messages are transmitted using RS485 protocol to provide fuel cell performance parameters system states warnings and alarms to a computer or external controller A 5 V start signal is applied to the Nexa module through the communications port Control signals are also transmitted here for the actuation of a load relay and external fuel isolation valves Figure 10 illustrates how the Communications Wiring Harness is connected to the control board 6 24 2002 Figure 10 Connecting the Communications Port Connecting the Serial Cable and Computer Figure 11 illustrates how the serial cable is used to connect the computer s serial port to the RS485 232 converter box of the Communications Wiring Harness Figure 11 Connecting the Serial Cable and Computer Commercial Confidential 34 Nexa Power Module User s Manual 5100078 BAL Installation 3 2 05 Installing the Load Relay Figure 12 illustrates how the load relay is connected to the positive output power lead of the Nexa module The signal wire which controls the relay is connected to
68. ce consisting of the Escape Character OxDB followed by the Escape Esc Character OxDC or the Escape End Character OxDD as appropriate Hence an encoded SLIP message is transmitted by the Nexa unit as a character stream that is a minimum of 43 bytes 0xCO 40 status bytes 1 byte checksum 0xCO and a maximum of 84 bytes In reality the 84 byte max will never be observed since the values 0xC0 and OxDB will never appear in the status message status code failure code warning bit map and acknowledgement fields As an aside the Nexa system has a Diagnostic Mode in which an extended status message is transmitted A receiver that knows only the structure of the basic Normal Mode message can still correctly process a Diagnostic Mode message without knowing its complete structure since the first 40 bytes of the diagnostic Mode message are the same as the Normal Mode message and the last byte is always the checksum over the entire message Thus the receiver should compute the checksum over any valid message it gets regardless of length and compare it to the last byte in the message to determine the message s validity Then the receiver can decide whether to make use of the first 40 bytes or the extended message as appropriate In summary the invocation of the SLIP decode routine by the receiver should not depend on or be triggered by the receipt of any specific of characters Instead the SLIP decode routine should be called whenever a 0xCO characte
69. ck architecture does not require external fuel humidification Furthermore this fuel cell stack is air cooled which further simplifies the overall system design The Nexa fuel cell stack has been sized to provide 1 2 kW of net output power The output voltage varies with power ranging from about 43 V at system idle to about 26 V at full load During Nexa system operation the fuel cell stack voltage is monitored for diagnostic control and safety purposes as shown in Figure 2 In addition a cell voltage checker CVC system monitors the performance of individual cell pairs and detects the presence of a poor cell The Nexa unit will shut down if cell failure or a potentially unsafe condition is detected in the fuel cell stack Hydrogen System The Nexa power module operates on pure dry hydrogen from any suitable source The fuel supply system as shown in Figure 2 monitors and regulates the supply of hydrogen to the fuel cell stack The fuel supply subsystem is comprised of the following components e pressure transducer monitors fuel delivery conditions to ensure an adequate fuel supply is present for Nexa system operation A pressure relief valve protects downstream components from over pressure conditions A solenoid valve provides isolation from the fuel supply during shut down A pressure regulator maintains appropriate hydrogen supply pressure to the fuel cells A hydrogen leak detector monitors for hydrogen levels
70. d Field Service for further support Execute Rejuvenation procedure on shut down for firmware revisions 00 03 01 or greater Call Ballard Field Service for further 103 Nexa Power Module User s Manual 5100078 DESCRIPTION OF WARNING OR FAILURE Fuel Cell Stack Current Fuel Pressure Low CVC Cell Voltage 3 2 05 POSSIBLE CAUSE Nexa system output power level is too high Fuel cell stack performance voltage is too low Failed current sensor or failed sensor signal to the control board Detected surge current from the fuel cell stack exceeds 70 amps Non Operating Performance Loss NOPL or fuel cell contamination air or fuel supply Fuel cell failure System is out of fuel Fuel delivery pressure is set too low Hydrogen solenoid valve is not working Fuel delivery assembly is leaking Shorted Cells Air pump failure Control board failure Localised overheating of cells Blocked oxidant air inlet or outlet Commercial Confidential BALLARD Planned SUGGESTED ACTION support Ensure continuous net power production does not exceed 1200W net Repeat Low Fuel Cell Stack Voltage troubleshooting suggestions above Check zero reading of onboard current sensor Contact Ballard Field Service for further support Provide current limiting in power conditioning design Ensure that current surges from the fuel cell stack exceeding 70 amps are shorter than
71. d not be cycled more frequently than every 5 seconds Battery power is drawn by the fuel cell system during the start up sequence the shut down sequence and during standby to run the microprocessor and the hydrogen sensor A summary of the expected power draw from the battery is provided in Table 22 Commercial Confidential 70 Nexa Power Module User s Manual MAN5100078 AN 6 Electrical Interface Operating Mode Estimated Max Power Estimated Max Time Off 0 Watts N A Standby 2 5 Watts N A Start up 35 Watts average 10 seconds Operating 0 Watts N A Normal Shut down 60 Watts 60 seconds Failure Shut down 60 Watts 1 2 seconds Note 1 Additional battery capacity is drawn during the automated rejuvenation process for firmware revisions 00 03 01 and greater Table 22 Expected Power Draw Requirements from the Battery When the Nexa system reaches its normal operating voltage gt 22V the fuel cell will take over the power supply for all ancillaries The battery remains disconnected until the stack voltage falls below 18V During normal operation a battery charger should be implemented into the final product design to re charge the battery from fuel cell power Battery charger integration is part of the OEM responsibility Depending on the end use duty cycle a larger battery may also be incorporated into the product to provide load sharing capability with the fuel cell
72. d purge valve tubing Non Operating Performance Loss NOPL or fuel cell contamination air or fuel supply Purge Cell failure Fuel Cell stack failure Confirm non restartable fault using software interface Fuel delivery assembly is leaking Commercial Confidential BALLARD Planned SUGGESTED ACTION Ensure hydrogen fuel supply satisfies the purity specification for the Nexa system Check zero reading of onboard current sensor Contact Ballard Field Service for further support Check CVC finger contacts Contact Ballard Field Service for further support Check CVC finger connectors Contact Ballard Field Service for further support Execute Rejuvenation procedure on shut down for firmware revisions 00 03 01 or greater Call Ballard Field Service for further support Repeat Low Fuel Cell Stack Voltage troubleshooting suggestions above Listen for audible clicking of purge valve during system operation Contact Ballard Field Service for further support Contact Ballard Field Service for further support Contact Ballard Field Service for further support Execute Rejuvenation procedure on shut down for firmware revisions 00 03 01 or greater Contact Ballard Field Service for further support Contact Ballard Field Service for further support Contact Ballard Field Service for further support Inspect the fuel cell stack fuel storage tanks solenoid valves and the connections to the f
73. dule is a fully automated system An onboard microprocessor regulates fuel cell operation executes startup and shut down sequences issues warning alarms and maintains safe operation at all times A serial port transmits fuel cell operational data to the OEM systems This section provides software and communication interface details which enable the OEM to access the serial message interpret Nexa operational data and develop a dedicated monitoring control and diagnostic interface for the end use product 7 1 Operating States Figure 32 shows the operation of the Nexa system software state machine The states Off Standby Start Up Normal Operation Normal Shutdown and Failure Shutdown are described below to assist with Nexa software integration Off Battery Power Battery Power Applied Removed Standby t Seri E Port Diagnostics Battery Power START Line ON Mode Enabled Removed i START Line OFF Check Startup Fault Conditions Fault Detected No Fault Conditions Exist Y Start Up Fault Detected gt Normal Shut Down Battery Power Removed mius Operating Fault cde Faut Detected gt START Line OFF No Fault Conditions Exist y C Normal Operation jJ Detected gt START Line OFF Rejuvenation Firmware 00 03 01 only Fault Detected If gt 200W for 10 30 min Y Norma Shut Down Failure Shut Down a Batte
74. duplicator fluid Remote Effects cathode but may control hobby airplane and car fuel be removed through antifreeze dry gas aerosol products oxidation during normal operation Sulphur Compounds Mercaptans Cosmetics shampoo latex paints Concern Low pesticides Can irreversibly absorb on catalyst Halides Chlorine Bromine or Household bleaches swimming pool Concern Low lodine as gaseous disinfectants Can irreversibly absorb decomposition on catalyst products Table 19 List of Contaminants and Common Sources Material Compatibility The design of a PEM fuel cell system requires attention to material compatibility issues that may differ from conventional engine design Trying to determine which specific materials are suitable for fuel cell use can be difficult as few materials are in a pure state Plastics can contain plasticizers Metallic components are usually alloyed and can be brazed or soldered together The best approach for determining fuel cell material compatibihty to avoid the possibility of MEA contamination considers the following e What materials are present e Whether a transport mechanism exists i e water or gas flow There are three general types of contaminants that are known to have a negative effect on fuel cell performance 1 Organic contaminants 2 Inorganic contaminants metals amp non metals 3 Gaseous contaminants The key factor as to whether the c
75. e 5 48000 Figure 40 Power De Rating Curves The Nexa module is capable of higher power levels than those shown in Figure 40 provided the fuel cell output voltage is permitted to fall below 26V 3 2 05 Commercial Confidential 98 Nexa Power Module User s Manual BAL 2n MAN5 100078 9 9 3 2 05 AN 9 Performance Characteristics Lifetime amp Degradation Characteristics Lifetime specifications for the Nexa power module are e 1500 hours of continuous operation e 500 start stop cycles e 2 years of storage Performance specifications for the Nexa power module are provided for beginning of life Over its lifetime fuel cell performance may degrade the amount depending on how the system is operated and stored The lifetime characteristics presented in this section describe how the performance of the Nexa module can be expected to vary over its lifetime and how that variation is affected by operating and storage conditions This information is considered typical for Nexa modules Individual units may vary Table 26 summarises the lifetime and degradation characteristics of the Nexa module evaluated under the following conditions over its specified lifetime e Steady state operation at full load 46A e Steady state operation at idle 35A e Dynamic load profiles that vary from idle OA to full load 46A e On Off cycling e Storage under freezing conditions e Storage under room
76. e a 40 bytes segment at the beginning of the message that includes all relevant operating data for the OEM Up to an additional 100 bytes may be added for diagnostic and fault code retrieval purposes to the end of the message These bytes should be considered unused bytes by the OEM except for the purposes of computing the checksum at the end of the message 4 In addition to the varying length of the message that accounts for the diagnostic transmission additional bytes are required to handle the transmission of the escape characters 5 Acheck sum is computed over the entire message and displayed as the last byte at the end of the message The check sum is computed as a simple summation of the message bytes Overflow bits are discarded The Check Sum does not include the Tags or any escape characters 6 Each character is sent containing 1 start bit 8 data bits no parity bit and 1 stop bit 7 The format for the message from the Nexa system to the OEM is given below Tag Status Fail Warning Last Command Stack Stack Stack Hydrogen Code Bitmap Acknowledge Temperature Voltage Current Pressure Hydrogen Cumulative Hydrogen Oxygen Ambient Purge Cell Concentration Consumption Concentration Temperature Voltage Additional diagnostic and fault code bytes Check Sum Tag 0 to 100 extra bytes 3 2 05 Commercial Confidential 80 3 2 05 8 10 11 12 Nexa Power M
77. e system cannot be turned on until a Field Service Support representative has reset it This precaution is implemented for failure modes that present a potential safety implication to the end user These include both hydrogen leak failures and self test microprocessor or sensor faults When either of these occur field service 15 required 11 3 Trouble Shooting Checklist DESCRIPTION OF WARNING OR FAILURE POSSIBLE CAUSE SUGGESTED ACTION Fuel Cell Stack Temperature 3 2 05 The Nexa system output power level is too high Ambient temperature is above the operating limit for the Nexa system Fuel cell stack performance voltage is too low Cooling fan intake obstructed Coolant exhaust obstructed Commercial Confidential Ensure continuous net power production does not exceed 1200W net Review the product specification for Repeat Low Fuel Cell Stack Voltage troubleshooting suggestions below Ensure cooling fan intake is unobstructed Ensure coolant exhaust is 102 Nexa Power Module User s Manual 5100078 DESCRIPTION OF WARNING OR FAILURE Fuel Cell Stack Voltage 3 2 05 POSSIBLE CAUSE Cooling fan motor is failing or has failed Air exhaust is cross leaking into fan intake Fuel cell failure Nexa system output power level is too high Fuel cell stack is not receiving sufficient oxidant air Oxidant air inlet is contaminated Inadequate i
78. ell Stack Current Normal Shut down Low Fuel Pressure Warning Low Cell Voltage Failure Shut down Fuel Leak Warning Low Fuel Pressure Non Restartable Low Oxygen Concentration Warning Fuel Leak Detected Low Purge Cell Voltage Warning Low Oxygen Concentration Low Ambient Temperature Low Purge Cell Voltage Low Battery Voltage Startup Time Expired Multiple warnings are indicated Self Test Fault concurrently Software Fault Table 1 Transmitted Status Warning and Alarm Codes Signal Engineering Unit Fuel Cell Stack Temperature eC Fuel Cell Stack Voltage Volts Fuel Cell Stack Current Amps Hydrogen Pressure Barg Hydrogen Concentration Ppm Cumulative Hydrogen Consumption Slpm Oxygen Concentration Ambient Temperature C Purge Cell Voltage mV Table 2 Transmitted Transducer Signals 3 2 05 Commercial Confidential 7 Nexa Power Module User s Manual 5100078 BAL XL 1 8 Safety Systems The Nexa power module has automatic provisions to ensure operator safety and prevent equipment damage A warning or alarm occurs when an unusual or unsafe operating condition occurs depending on severity During a warning the power module continues to operate and the controller attempts to remedy the condition During an alarm the controller initiates a controlled shutdown sequence The Nexa power module employs the following monitoring and shut down mechanisms to ensure safe fuel cell operation is maintained a
79. ensor Offset B 0 94 Current Sensor Offset B 13 03 FAULT STATISTICS Normal Shutdowns 53 HIgh Stack Temperature 0 Low Stack Voltage 0 High Stack Current 0 Low Cell Voltage 0 Low Fuel Pressure 6 Fuel Leak Detected 0 Low Oxygen Concentration 0 Low Ambient Temperature 0 Low Purge Cell Voltage 0 Low Battery Voltage 17 Startup Time Expired 0 Selftest Fault 3 Software Fault 1 Startups Resets 186 CUMULATIVE SYSTEM DATA CELL Last Shutdown Failure Type FAILURE 3 2 05 Commercial Confidential 49 Nexa Power Module User s Manual 5100078 Total System Lifetime 0033 27 29 Total Stack Lifetime 0017 18 17 Cumulative Resuscitations 3 LAST FUEL CELL FAULT STATUS DATA System State at Time of Fault WARNING System Fault Type LOW FUEL P System Warning Bit Mask 0x04 Last Command Acknowledged ENTER DIAG System Selftest Status NO FAILURE Purge Status ON Purge Valve OPEN Resuscitation Status OFF Total Resuscitations 3 System Start Line Status ON Cell Voltage Checking ON Stack Temperature C 28 85 Stack Voltage V 41 92 Stack Current A 1 80 Fuel Pressure barg 0 34 Fuel Leak Alarm 35 64 Fuel Consumption L 0 08 O2 Concentration 20 93 Air Temperature C 24 62 Purge Cell Voltage mV 1854 84 Battery Voltage V 25 19 Air Flow slpm 18 77 Pump 12 3 V 4 07 H2 Leg Voltage V 1 28 Pump Duty Cycle 43 00 Fan Duty Cycle 50 00 Stack Power
80. er draw during start up 60 W Operating Location Acceptable locations for use Indoors amp Outdoors Environment Temperature Range of acceptable ambient cooling air and 3 C 40 C Range oxidant air temperatures Relative Humidity Range of acceptable ambient relative humidity 0 95 non condensing EMI Tolerance Tolerant to and operates safely in the EMI UL 991 environment specified by 3 2 05 Commercial Confidential Nexa Power Module User s Manual BAL 2n An MAN5 100078 NOTE 1 Exercise the Nexa power module every 2 3 months to maintain peak performance Operate at half power for 10 30 minutes to initiate the automated rejuvenation cycle on shut down NOTE 2 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 25 for warning and shut down values Table 4 Nexa Product Specification 2 2 Shipping amp Storage Specification This section addresses required methods and criteria for packaging shipping and storing the Nexa power module as well as end products developed using the Nexa module Adhere to these specifications to ensure that damage or performance loss does not occur The identified Original Packaging Assembly is to be used
81. esaeeecsagas 35 FIGURE 13 CONNECTING THE HYDROGEN SUPPLY 35 FIGURE 14 NEXAMON OEM MAIN SCREEN cetero tnter ttt astennas 37 FIGURE 15 CONFIGURING A DATA LOG FILE ccssccccesssecesesscecseseeecsesaececeececsesaeeecsesaececeaeecsesaeeecseaaeeeseseeesesaeseceagas 42 FIGURE 16 SAMPLE OF DATA LOGGING FILE ccssccccssssececssececeeseeecessaeeeceeseeceesaeeecsesaececeeseeesesaeeecsesaeesceeseeessaeeeengas 45 FIGURE 17 SAMPLE OF LAST FAULT DATA SCREEN sesseeeeeeeee eene enne ener niente nennen rennen nent nre nter sene rens enne 47 FIGURE 18 SAMPLE OF HISTORICAL FAULT DATA SCREEN cssssscecessseeecssccecseseeecseaeececueeecsesaececsasececeeeeesesaeeecseaaees 48 FIGURE 19 SAMPLE OF DIAGNOSTIC DATA REPORT ccccsssssesessseeecseseececseeeceesaececseaeesecsueeecsesaeeeceesaeessaeeessesaeeeeeeaaees 51 FIGURE 20 RESETTING NON RESTARTABLE FAULTS cccsssscessseeecseseececsnececsssaececseaeececsueeecsesaececseseeeesseeesseaeeseeeaaees 52 FIGURE 21 CHANGING THE SERIAL PORT cccseecccesssceesecsssecseccecesdenceceesessucessoecscussececssadsucsecesessnssssessassuessnceedessneess 53 FIGURE 22 LEFT SIDE VIEW OF THE NEXA POWER MODULE eee enne 54 FIGURE 23 RIGHT SIDE VIEW OF THE NEXA POWER 55 FIGURE 24 BASE VIEW OF THE NEXA POWER 5
82. essure O l FC Current Air Mass Flow Cell Voltage FC Voltage Purge Cell Voltage e On Off Signal Main Gas Valve e Serial Port Communication 3 2 05 Fuel Cell Air Compressor Humidity Exchanger TD Cooling Fan s Output Output Diode Relay Figure 2 Nexa System Schematic Commercial Confidential 2 Regulator Nexa Power Module User s Manual BAL AKL 5100078 1 2 3 2 05 Fuel Cell Principles The fundamental component of the Ballard fuel cell consists of two electrodes the anode and the cathode separated by a polymer membrane electrolyte Each of the electrodes is coated on one side with a thin platinum catalyst layer The electrodes catalyst and membrane together form the membrane electrode assembly A single fuel cell consists of a membrane electrode assembly and two flow field plates as shown in Figure 3 PEM Proton Exchange Membrane Fuel Flow Field Plate Oxidant Flow Field Plate Exhaust gt Fuel Water Vapor No Pollution Low Temperature Electrochemical Process Heat Air Fuel Hydrogen Figure 3 PEM Fuel Cell Principals Gases hydrogen and air are supplied to the electrodes on either side of the membrane through channels formed in the flow field plates Hydrogen flows through the cha
83. exa control board to avoid communications failure due to ground currents A 100Q resistor is used to connect the COM channel of the communications port to the ground of the control board to avoid large ground currents from developing Commercial Confidential 73 Nexa Power Module User s Manual BAL i 2n 51 N5100078 6 Electrical Interface 3 2 05 Nexa M Power Module Optical Isolator Computer Control Board Tx Rx Power Comm Supply RS485 to RS232 Serial Interface 100 Q Ground of wall outlet Figure 30 Grounding of Communications Signals Figure 31 illustrates the energizing of external actuators such as the hydrogen solenoid valve that isolates the OEMs fuel supply The solenoid valve is powered by a 13 5V signal from the Nexa control board When the FET transistor is turned on it completes the circuit by providing a ground path It is recommended that the valve casing be connected to the chassis ground earth ground for safety 13 5V Nexa Control Board Hydrogen Solenoid l J4 B4 ee oo J4 B3 FET transistor to ground To OEM System Ground To Stack Figure 31 Grounding of External Valves and Actuators Commercial Confidential 74 Nexa Power Module User s Manual BAL 2n MAN5 100078 an 7 Software and Communications 7 Software and Communications The Nexa power mo
84. express written consent of Ballard Certification The Nexa power module is UL and CSA approved Q NM us A Disclaimer This manual incorporates safety guidelines and recommendations However it is not intended to cover all situations Itis the responsibility of the customer to meet all local safety requirements and to ensure safety during operation maintenance and storage of the Nexa power module Although all efforts have been made to ensure the accuracy and completeness of the information contained in this document Ballard reserves the right to change the information at any time and assumes no liability for its accuracy Commercial Confidential iii Nexa Power Module User s Manual MAN5100078 BALLAR v Glossary Nexa Power Module AC Alternating Current BAR g Bar gauge pressure Cold Start A start up attempt when Nexa has reached a steady state at ambient temperature Cell Voltage Checking system DBA Decibel DC Direct Current Fuel cell stack Individual fuel cells combined Indoors Inside a building or shelter where natural airflow is limited or enhanced by forced ventilation systems kW Kilowatt kPa g Kilo Pascals gauge pressure LPH Litres per hour MTBF Mean Time Between Failure OEM Original Equipment Manufacturer Outdoors Location where natural airflow is not restricted and where Nexa is sufficie
85. for all shipments of the Nexa power module Warranty returns of Nexa modules to Ballard must be packaged in the designated shipping crate assembles Nexa packaging must be in good condition Physical damage to the crate due to misuse or outside storage will void the warranty claim Nexa specifications are subject to change Refer to the Ballard document Nexa Shipping and Storage Specification attached to your Sales Contract for the specifications of your Nexa power modules 3 2 05 Commercial Confidential 13 Nexa Power Module User s Manual 5100078 Requirements Definition Description Quantity Nexa Crate Assembly Nexa Single Pack Shipping Crate Part 5000233 Module Nexa Single Pack Packaging Foam Lower Pad Part 5000234 Packaging Foam Top Pad Part 5000226 Crate Assembly Nexa Four Pack Shipping Crate Part 5000197 Nexa Four Pack Packaging Foam Pad Part 5000198 End Product Packaging Foam The following packaging foam is recommended Packaging for packaging end products using the Nexa module Stratocell amp Polyethylene Foam a product of Sealed Air Corporation Park 80 East Saddle Brook NJ 07663 Consult Ballard before using other foams styrofoams or materials Transport Mode s of Transport The Nexa power module is capable of being shipped by water road or air Mode of Operation The Nexa power module will not be operated Du
86. gnostics Confirm purge valve clicks and visually inspect for hydrogen venting Call Ballard Field Service for support Refer to Low Stack Voltage troubleshooting suggestions Contact Ballard Field Service for support Execute Rejuvenation procedure on shut down for firmware revisions 00 03 01 or greater Verify that the load relay is open on system start up Contact Ballard Field Service for further support Check sensor connections Contact Ballard Field Service for further information Check the pins and connector Call Ballard Field Service 106
87. hecksum byte has been damaged or dropped then the checksum calculation that follows the SLIP decode will detect the damaged message Note that it is crucial that a character beginning and ending with 0xCO not be passed to the SLIP decode routine If a OxCO appears in the receive data passed to this routine it must only be at the end of the buffer The serial receive algorithm outlined above guarantees that this is the case Under normal circumstances where there is no noise on the serial line the receive interface will get both the leading 0xCO and the trailing 0xCO In Receive Algorithm A above the leading 0xCO will be passed to the SLIP decode routine by itself Since it is preceded by no data the SLIP decode routine will return 0 indicating that a valid SLIP message has not been received When the trailing OxCO is received the SLIP encoded message and the trailing 0xCO will be passed to the SLIP decode routine and the message will be properly decoded Therefore it is typical that the SLIP decode routine will be called twice for each status message transmitted by the Nexa system the first time for the leading 0xCO and the second time for the status message and the trailing 0xCO In Receive Algorithm B a simplification of Receive Algorithm A the SLIP decode routine is invoked only once per Nexa status message since the 0xCO character is not added to the receive buffer and the decode routine is called only if the receive buffer is not e
88. iants Effects of oxygen deficiency may include rapid breathing diminished mental alertness impaired muscular coordination faulty judgement depression of all sensations emotional instability and fatigue As asphyxiation progresses nausea vomiting prostration and loss of consciousness may result eventually leading to convulsions coma and death At concentrations below 12 immediate unconsciousness may occur with no prior warning symptoms WARNING Lack of oxygen can lead to unconsciousness and asphyxiation Oxygen is consumed from the ambient air during power module operation To guard against oxygen depletion an oxygen sensor mounted on the controller monitors the ambient oxygen concentration This sensor triggers warnings and alarms before the oxygen concentration drops to a dangerous level As a preventative measure the Nexa power module must be operated in a well ventilated area in order to compensate for the oxygen used within the fuel cells WARNING Always operate the Nexa power module in a well ventilated area Electrical Safety WARNING Avoid contact with an exposed fuel cell stack Electrical shock can cause personal injury or death e Do not touch fuel cell plates or any electrical components at any time A running fuel cell stack is a potential electrical hazard that can cause burns or electrical shock e Do not wear metallic jewellery rings bracelets watchbands or necklaces when
89. ided in Table 7 Description Specification Composition Ambient air Pressure Atmospheric Flow 90 slpm Connection None External ducting is recommended to separate the process air inlet stream from the cooling air outlet Table 7 Process Air Inlet Connection 2 3 3 Process Air Outlet The process air outlet expels oxygen depleted air after its use in the fuel cell power reaction Excess product water from the fuel cell power reaction is entrained in the process outlet air stream in both liquid and vapour form Specifications for the process air outlet connection are provided in Table 8 Description Specification Composition Oxygen depleted air Maximum allowable flow restriction on outlet connection measured as pressure drop to 3 44 kPa 0 5 psi at 100 SLPM 55 ambient Temperature lt 55 C depends on the fuel cell stack operating temperature Flow See process air inlet Entrained Product Water 870 mL hour maximum at rated power Connection 16 mm OD tube Table 8 Process Air Outlet Connection 2 3 4 Cooling Air Inlet The cooling air inlet draws air from the ambient surroundings in order to cool the fuel cell stack and regulate operating temperature Specifications for the cooling air inlet connection are provided in Table 9 3 2 05 Commercial Confidential 18 Nexa Power Module User s Manual MAN5100078
90. ilter may be needed depending on the ambient air quality The filter should not be cleaned since the used cleansing agent could be a source of contamination for the fuel cell For periodic maintenance ensure that the air filter is accessible when designing the final product packaging Also ducting should be incorporated in the product packaging to ensure cool fresh air is supplied to the oxidant inlet Separation of the air pump inlet and cooling air exhaust is recommended The Nexa power module produces water as a by product of the fuel cell reaction Excess product water is discharged in the oxidant air exhaust as both liquid and vapour At full power approximately 870 ml hour are generated Detailed water production curves are provided in the Performance Characteristics section of this guide System integration requires design strategies for handling excess product water Product water may be evaporated passively into the ambient environment or condensed and collected Ensure that downstream processes do not add excessive flow restriction to the air pump to maintain adequate airflow to the fuel cells Refer to Table 17 for details Figure 23 illustrates the oxidant air outlet connection to the Nexa system A check valve on the outlet of the humidity exchanger isolates the oxidant exhaust when the system is shut down keeping the fuel cell stack humidified during periods of storage A 16 mm OD tube stub is provided for external connection t
91. in the event of an alarm shutdown e Under normal operation hydrogen released by way of the purge solenoid valve mixes with the cooling air stream where it quickly diffuses and dilutes to levels far below the LFL of hydrogen This eliminates the potential formation of a flammable gas mixture in the cooling air flow and permits indoor operation e A pressure relief valve discharges hydrogen into the cooling air stream during overpres sure conditions to protect the fuel cell stack from damage When the relief valve opens the hydrogen concentrations measured in the cooling air stream exceed the hydrogen sensor alarm setting and the power module shuts down 3 2 05 Commercial Confidential 8 Nexa Power Module User s Manual BALLARD MAN5 100078 1 9 3 2 05 Operation The Nexa power module provides fully automated operation and load response In order to operate the unit one must provide a 24V battery connection to support start up and shut down loads provide an adequate hydrogen fuel supply and apply a 5V start signal to the control board Once these steps are taken the Nexa module will export unconditioned DC electric power on demand Before battery power is applied the Nexa module remains in the OFF state In this state the onboard sensors actuators and microprocessor are de energised and therefore unavailable for operation Once the 24V battery connection is applied to the control board the Nexa
92. ings present The warning codes are combined with OR logic to form a single byte For example to send Low Fuel Cell Stack Voltage and Low Fuel Pressure Warnings simultaneously the code 0 0 would be sent The Last Command Acknowledge is a repetition of the last command received from the OEM See below for the structure of commands sent to the Nexa system Commercial Confidential 81 Nexa Power Module User s Manual BAL 2n An 7 Software and Communications MANS5 100078 13 The data Fuel Cell Stack Temperature Voltage Current Hydrogen Pressure Hydrogen Concentration and Cumulative Hydrogen Consumption Oxygen Concentration are sent as floating point numbers using the following 4 byte format as follows Sign 1 bit Exponent 8 bits Mantissa 23 bits The 4 bytes are arranged in the following fashion Sign 1 bit Exponent LSB Mantissa Mantissa Exponent 7 MSB s Mantissa 7 MSB s 8 bits 8 LSB s Fourth Byte Sent Third Byte Second Byte First Byte The mantissa and the exponent are arranged so that the Most Significant Bit MSB 15 on the left and the Least Significant Bit LSB is on the right To convert this format into a decimal number the following formula is used X 1y 290979 1 Mantissa Where Signis either 1 or 0 Exponent is 8 bits 0 to 255 Mantissa is 23 bits Example The number 446 28 would be sent as OxB8 Ox 1E 0x3
93. k current air mass flow fuel cell stack voltage and purge cell voltage The status of the Cell Voltage Checker CVC system is also an input to the control board presenting either a Pass or Fail result for the operational status of the stack Finally the ambient oxygen concentration is measured by an onboard sensor and sent to the controller to ensure a safe operating environment for the user Analogue and digital output control signals are issued from the control board to regulate system operation Control commands are issued for opening and closing the hydrogen solenoid valve and purge valve of the Nexa module The speed of the air compressor is varied based on current demand The speed of the cooling fan is also controlled to regulate the fuel cell stack temperature An external load relay is opened or closed by the Nexa control system for engaging or disengaging the fuel cell stack to external loads The control system also issues a signal for opening and closing external solenoid valves to isolate hydrogen storage tanks when the Nexa module is not in operation Communications to and from the end product are made via the Nexa control board An on off signal is issued to the fuel cell control board for starting or stopping the Nexa module The controller communicates with external equipment using the RS 485 serial link Data transmitted from the control board includes status and performance information The control board will also
94. l SS 316L has shown the best passivity 3 2 05 Commercial Confidential 66 Nexa Power Module User s Manual BAL 2n MAN5 100078 5 7 2 2 5 7 3 AN 5 Mechanical Interface in water Metals that develop passive layers or are naturally immune at the pHs and potentials present in a fuel cell are be the best metals to consider for use in fuel cell systems Non metals Non metals include materials containing boron B silicon Si sulfur S chlorine Cl arsenic As selenium Se phosphorous P bromine Br tellurium Te and iodine 1 Many of these materials B P As Se Te Br are not likely to be found in materials used in fuel cell systems Some elements like arsenic and selenium are known to be catayst poisons and should be avoided The other elements Si S Cl occur quite frequently in various materials used in fuel cells and fuel cell systems Silicon is the main component in silicone seals greases and oils Ballard has used various silicone and fluorosilicone seals with some success Silicone oils and greases have seen shown to negatively impact fuel cell performance Chlorine containing compounds should also be avoided as chlorine can adhere to the catalyst Silica glass S1O itself is not believed to cause any deleterious effects of fuel cells as the silica is fully oxidised Sulphur and sulphur containing compounds thiols mercaptans are used extensively as plasticizing agents in ma
95. mechanisms that cause hydrogen embrittlement effects are not well defined Factors known to influence the rate and severity of hydrogen embrittlement include hydrogen concentration hydrogen pressure temperature hydrogen purity type of impurity stress level stress rate metal composition metal tensile strength grain size microstructure and heat treatment history Moisture content in the hydrogen gas may lead to metal embrittlement through the acceleration of the formation of fatigue cracks Hydrogen embrittlement can lead to leakage or catastrophic failures in metal and non metallic components Commercial Confidential 24 Nexa Power Module User s Manual BALLARD MANS5 100078 3 2 3 3 2 05 Hydrogen leaks emanating from the fuel cell stack are readily detected by way of the hydro gen sensor mounted in the cooling air outlet stream This sensor triggers warnings and alarms well before the hydrogen air mixture reaches a flammable concentration As a preventative measure the Nexa power module must be operated in a well ventilated area in order to inhibit potential hydrogen accumulation WARNING Always operate the Nexa power module in a well ventilated area and ensure that ventilation slots are unobstructed Flammability and Volatility Hydrogen is flammable over concentrations of 4 75 by volume in air and is explosive over concentrations of 15 59 As result even small leaks of hydrogen h
96. mp Replacement of the fuel cell stack cooling fan purge valve and control board will likely require that the Nexa be removed from the OEM s product On an ongoing operating basis the air filter is the only component requiring routine maintenance 3 2 05 Commercial Confidential 87 Nexa Power Module User s Manual 5100078 BALLARD 8 Product Integration 8 5 Certification Requirements 8 5 1 CSA Certification The Nexa Power Module is a CSA approved under CSA Class 2725 Sections 01 and 81 Fuel Cell Power Generators Any physical or software change made to this product will void this certification as well as the UL recognition An OEM integrating the Nexa power module in a commercial product must consider the following conditions of acceptability in order to retain the CSA approval e The Fuel Gas Valve train valves controls piping and tubing through which hydrogen is supplied to the Fuel Cell Stack and by which hydrogen gas is controlled shall be evaluated in the end product e end product manufacturer shall be informed of the low voltage limit setting as design parameter due to the variations of the minimum voltage e This Fuel Cell Module shall be used with a non field adjustable certified pressure regulator with a 5psi outlet pressure e suitability for use in a hazardous location area of the oxygen sensor hydrogen sensor and PCB Controller shall be evaluated in the end pr
97. mpty Commercial Confidential 85 Nexa Power Module User s Manual BAL 2n MAN5 100078 8 2 8 3 3 2 05 AN 8 Product Integration Product Integration Packaging amp Enclosure Design The Nexa power module has been developed for both indoor and outdoor application Allowable outdoor applications are restricted to cases where the DC module is sufficiently protected by the OEM end product outer enclosure against inclement weather The fuel cell system should never be operated in wet freezing or marine conditions The system should also be adequately protected from wind blown sand and dust The Nexa system is rated for ambient temperatures ranging from 3 C to 30 C The power module has not been designed for freezing start conditions and the system will not start up if the ambient temperature is measured to be less than 3 C The Nexa control board measures ambient temperature adjacent to the fuel cell stack Once the system is operating waste heat from the fuel cell reaction warms its immediate surroundings and increases the corresponding ambient temperature reading Subzero operation may be possible after the system is running depending on the packaging design implemented by the OEM However the OEM must ensure that the system is turned off if at any time the ambient temperature is measured to be below 3 C by the Nexa control board Electro Magnetic Interference The Nexa power module has been th
98. near the fuel delivery subassembly Warning and shut down alarms are implemented for product safety The fuel cell stack is pressurised with hydrogen during operation The regulator assembly continually replenishes hydrogen which is consumed in the fuel cell reaction Nitrogen and product water in the air stream slowly migrates across the fuel cell membranes and gradually accumulates in the hydrogen stream The accumulation of nitrogen and water in the anode results in the steady decrease in performance of certain key fuel cells which are termed purge cells In response to the purge cell voltage a hydrogen purge valve at the stack outlet is periodically opened to flush out inert constituents in the anode and restore performance Only a small amount of hydrogen purges from the system less than one percent of the overall fuel consumption rate Purged hydrogen is discharged into the cooling air stream before it leaves the Nexa system as shown in Figure 2 Hydrogen quickly diffuses into the cooling air stream and is diluted to levels many times less than the lower flammability limit The hydrogen leak detector situated in the cooling air exhaust ensures that flammable limits are not reached This feature permits safe indoor operation of the Nexa power module Commercial Confidential 4 Nexa Power Module User s Manual 5100078 BAL XL 1 5 Oxidant Air System A small compressor provides excess oxidant air to the
99. nlet air humidification Purge valve is not working Hydrogen fuel supply is contaminated Onboard current sensor is un calibrated Short circuit through an external conductor on near the stack Non Operating Performance Loss NOPL or fuel cell contamination air or fuel supply Fuel cell failure Commercial Confidential BALLARD Planned SUGGESTED ACTION unobstructed Perform audio visual inspection of fan and motor Call Ballard Field Service for further support Check the product enclosure for gaps and cracks Call Ballard Field Service if the problem persists Ensure continuous net power production does not exceed 1200W net Review power de rating requirements Listen for air pump operation Call Ballard Field Service if a problem is found Check humidity exchanger for leaks Call Ballard Field Service for replacement humidity exchanger Check air filter for blockages Ensure the Nexa system is not running adjacent to automobile or portable generator exhaust Consult end user on operating environment Call Ballard Field Service for replacement humidity exchanger Call Ballard Field Service to perform a more detailed diagnosis Ensure hydrogen fuel supply satisfies the purity specification for the Nexa system Check zero reading of onboard current sensor Call Ballard Field Service for further support Inspect stack and terminals for debris or damage Contact Ballar
100. nnections Detailed specifications are also provided for the hydrogen supply cathode air and cooling air interface Physical Layout Connections amp Dimensions The physical layout and dimensions of the Nexa system are shown in the following figures The location and description of interface connections for process gases electrical power and communications is also provided A solid model of the Nexa system layout and interface connections is included as part of this manual to assist OEMs in their installation and packaging design Speak to a Ballard Customer Support representative for information ARE 5 3D AND 5 ABOUT VALVE AXIS REQUIRED Unless otherwise specified dimensions are in millimeters BATTERY POWER CONNECTOR Figure 22 Left Side View of the Nexa Power Module Commercial Confidential 54 Nexa Power Module User s Manual BAL 2n MAN5100078 AN Interface OXIDANT AIR IN UOLING AIR OUT 1 B o L l Ll i Figure 23 Right Side View of the Nexa Power Module ef 4154 2 152 MAX La ms uu S ue aS Sal T7 bod m e PRSTTMT Za FUEL 9 POWER OUT 1 4 INCH POSITIVE RED 190 10 M NEGATIVE BLACK 325 10 MM Figure 24 Base View of the Nexa Power Module 3 2 05 Commercial Confidential 55 Nexa Power M
101. nnels to the anode where the platinum catalyst promotes its separation into protons and electrons The free electrons are conducted in the form of usable electric current through an external circuit while the protons migrate through the membrane electrolyte to the cathode At the cathode oxygen from the air electrons from the external circuit and protons combine to form pure water and heat Individual fuel cells are combined into a fuel cell stack to provide the required electrical power A single fuel cell produces about 1 volt at open circuit and about 0 6 volts at full load Cells are stacked together in series to provide the required output voltage In turn the output current of a fuel cell is proportional to its active area Consequently the fuel cell stack geometry can be tailored to provide the desired output voltage current and power characteristics Commercial Confidential 3 Nexa Power Module User s Manual BALLARD MAN5 100078 1 3 1 4 3 2 05 Fuel Cell Stack PEM fuel cell stacks produce unregulated DC power from hydrogen and air Water and heat are the only by products of the reaction The PEM fuel cell stack incorporated into the Nexa system has been developed with a number of important attributes for the portable power market First the Nexa fuel cell stack operates at low pressure minimising parasitic losses reducing noise and enhancing system reliability Second the Nexa fuel cell sta
102. nning of life BOL net system efficiency of Nexa power module as a function of net output current and net output power The system efficiency presented in Figure 35 is defined by the ration of net output power to the lower heating value of hydrogen consumed in the fuel cell reaction The Nexa system efficiency at full power is approximately 38 Maximum system efficiency is about 50 and occurs at part load approximately 300W net The system efficiency quickly declines for part loads less than 30 dominate the requirement for hydrogen consumption OW as the auxiliary loads begin to 0 70 1400 0 60 1200 S 0 50 1000 x 0 40 800 c 2 0 30 600 E o gt w 020 400 z 0 10 200 0 00 0 0 5 10 15 20 25 30 35 40 45 50 Net Current Amps Net Efficiency Net Power Figure 35 Net System Efficiency Curve 3 2 05 Commercial Confidential 93 Power Watts Nexa Power Module User s Manual MAN5100078 BAL 9 Performance Characteristics 9 4 3 2 05 Power Heat Watts Heat Production Figure 36 illustrates the beginning of life BOL total Nexa system heat production as a function of net output current and average net output power The waste heat production of the Nexa power module increases with increasing load as the voltage and efficiency of the unit is reduced and the parasitic loads increase At rated power approximately 1650 watts of
103. ntly protected by an outer enclosure against bad weather Never operate Nexa in wet freezing or marine conditions Nexa must always be protected from wind blowing sand and dust PSIG Pounds per square inch gauge pressure SCFM Standard cubic feet per minute SLPM Standard litre per minute measured at 1 atm 0 C UPS Uninterrupted power supply V Volt VDC Voltage Direct Current BOL Beginning of Life EOL End of Life 3 2 05 Commercial Confidential Nexa Power Module User s Manual MAN5100078 BAL CONTENTS I REVISION HISTORY CONFIDENTIALITY IV CERTIFICATION DISCLAIMER V GLOSSARY 1 INTRODUCTION 1 1 1 2 1 3 1 4 1 5 1 6 1 1 8 1 9 1 10 GENERAL DESCRIPTION FUEL CELL PRINCIPLES FUEL CELL STACK HYDROGEN SYSTEM OXIDANT AIR SYSTEM COOLING SYSTEM ELECTRONIC CONTROL SYSTEM SAFETY SYSTEMS OPERATION PERIODIC EXERCISING 2 SPECIFICATIONS 2 1 PRODUCT SPECIFICATION 2 2 SHIPPING amp STORAGE SPECIFICATION 2 3 INTERFACE SPECIFICATIONS 3 SAFETY 3 1 GENERAL INFORMATION 3 2 USING HYDROGEN 3 3 OXYGEN DEPLETION 3 4 ELECTRICAL SAFETY 3 5 HIGH TEMPERATURE 3 6 HIGH PRESSURE 3 7 ROTATING EQUIPMENT 4 INSTALLATION 4 1 4 2 INSTALLATION KIT NEXAMON OEM SOFTWARE 5 MECHANICAL INTERFACE 5 1 5 2 5 3 5 4 5 5 5 6 3 2 05 PHYSICAL LAYOUT CONNECTIONS amp DIMENSIONS HYDROGEN SUPPLY INTERFACE OXIDANT AIR INTERFACE COOLING AIR INTERFAC
104. ny rubbers Sulphur and sulphur containing compounds cannot be tolerated to any extent in a fuel cell system Even small amounts can severely affect fuel cell performance Gaseous Contaminants These items include compounds like nitrous oxides NO and NO2 ammonia NH3 sulfurous oxides SO and SO carbon monoxide and dioxide CO and hydrocarbons reduced sulphur compounds PM10 total suspended particulate and suspended metals Many of these compounds are air borne pollutants These materials are typical environmental pollutants and may not be present in fuel cell materials but were included for completeness Unless the fuel cell system materials degrade and out gas these compounds they need not be considered Note however that some of the gt Mercaptans are used to scent natural gas and other potentially dangerous fuels Naturally occurring compounds that come from bogs swamps etc 5 Atmospheric particulates 10 um or less in diameter 3 2 05 Commercial Confidential 67 Nexa Power Module User s Manual BAL 2n 5100078 AN 5 Mechanical Interface gaseous compounds SO2 SO CO hydrocarbons are known to poison the fuel cell There is evidence that nitrous oxides may also contaminate fuel cells 3 2 05 Commercial Confidential 68 Nexa Power Module User s Manual MAN5100078 BAL j 6 Electrical Interface Electrical Interface Figure 27
105. o consider that some plastics and adhesives degrade over time depending on their local conditions potential water heat chemical attack stress etc and may release organic contaminants to the fuel cell The following materials have been identified as incompatible with PEM fuel cell systems either because they degrade under normal fuel cell conditions or they have a tendency to off gas harmful VOCs semi VOCs Table 20 does not present an exhaustive list of incompatible materials but rather provides an example of materials and their issues with fuel cell system integration Material Used in Issue Nylon 66 Water circuits Degrades in water circuits Polyester Gasketing over Degrades in oxidising membrane MEA environment Urethanes Acoustic foam packing Gives off aromatic VOCs Poly urethanes foam resulting in degradation Ultem poly ether imide Gasketing over Degrades in oxidising membrane MEA environment Table 20 Known Incompatible Materials 5 7 2 Inorganic Contaminants 5 7 2 1 Metals In general all metallic cationic contaminants pose a contamination risk However transport of the contaminants to the fuel cell usually requires water This is assuming that the components have been cleaned and there is no metallic dust present Without water present cationic contamination can be avoided If no transport mechanisms are present all metals should be acceptable However stainless stee
106. o the cathode air exhaust Commercial Confidential 60 Nexa Power Module User s Manual MAN5100078 An 5 Mechanical Interface Requirement Description Quantity Oxidant Type Ambient Air Air Inlet Supply Pressure Atmospheric 1 atmosphere Air Flow Rate Oxidant air flow rate at maximum power beginning of life lt 90 slpm lt 90 slpm Air Inlet Filtration The Nexa DC Power Module incorporates an oxidant air inlet filter Additional filtration is not required None required determined by fuel cell stack operating temperature Air Inlet Connection Ducting is recommended to separate the Ducting oxidant air inlet from cooling air exhaust recommended Air Outlet Connection Check valve preserves stack hydrogen 16 mm OD during storage Outer diameter of oxidant air outlet tube is 16 mm Air Outlet Temperature Oxidant air outlet temperature is lt 55 C Flow Rate of Product Water Maximum flow rate of product water at rated power as both liquid and vapour lt 870 ml hour Air Outlet Restriction Maximum flow restriction on outlet duct of oxidant air stream at 100 slpm air flow rate 55 C as measured by pressure drop to ambient 3 4 kPa g 0 5 psi Table 17 Oxidant Air Inlet and Outlet Interface Specifications 3 2 05 Commercial Confidential 61 Nexa Power Module User s Manual BAL 2n 5100078 5 4 3 2 05
107. oduct e The module grounding shall be evaluated in the end product e The end product for which this fuel cell module is intended must be evaluated to approved requirements e The reliability and suitability of the software to provide safety control of the fuel cell module must be evaluated in the end product to ensure compliance with standards IEC730 or UL1998 e stainless steel isolating plate of the purge valve was not evaluated for compatibility of materials with the working fluids For further information on CSA certification please refer to the CSA Master Contract 201446 and Report 1135246 or contact your Ballard Power Systems Customer Support Representative 8 5 2 UL Certification 3 2 05 The Nexa Power module is also recognised by Underwriters Laboratories UL OEM looking to have their products also recognised by UL also must ensure the following Conditions of Acceptability are met e Product shall be used within the ratings noted e Grounding of dead metal parts shall be accomplished in the end application Commercial Confidential 88 Nexa Power Module User s Manual BAL 8 Product Integration MAN5100078 e It shall be determined in the end application if air purging prior to module start up ambient air ventilation and equipment shutdown in the event of air ventilation failure is adequate e Means shall be provided to seal the fuel manifold pressure regulator adjustmen
108. odule User s Manual BAL 2n MAN5100078 AN 5 Mechanical Interface PASA ly E VETT ASSEMBLY SEE NEXT PAGE POSITION FIXED REGARDLESS OF STACK LENGTH Figure 25 Top view of the Nexa Power Module pn c H T Figure 26 Front and Back Views of the Nexa Power Module 3 2 05 Commercial Confidential 56 Nexa Power Module User s Manual MAN5100078 5 2 Hydrogen Supply Interface an 5 Mechanical Interface Hydrogen supply interface specifications for the Nexa power module are shown in NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 14 for warning and shut down values Table 16 The Nexa fuel cell system is designed for operation on pure gaseous hydrogen No fuel humidification is required Hydrogen can be supplied at pressures ranging from 70 kPa g to 1720 kPa g pressure relief valve is set for 2400 kPa g to ensure overpressure conditions are not applied to the downstream pressure regulator assembly The relief valve discharges into the vicinity of the onboard hydrogen leak detector thereby shutting down the system in the event of excessive inlet supply pressure NO
109. odule User s Manual BAL i 2n AN51 7 Software and Communications Information in the message header and footer the 2 Tags the Status the Fail Code the Warning Bitmap the Last Command Acknowledge and the Check Sum are sent as single bytes The Nexa system has the following Status Codes 0x00 Standby 0x01 Start up 0x02 Normal Operation 0x03 Warning 0x04 Normal Shut Down 0x05 Failure Shut Down 0x06 Non Restartable The Nexa system has the following Fail Codes 0x00 Normal Operation 0x01 High Fuel Cell Stack Temperature 0x02 Low Fuel Cell Stack Voltage 0x03 High Fuel Cell Stack Current 0x04 Low Cell Voltage 0x05 Low Fuel Pressure 0x06 Fuel Leak Detected 0x07 Low Oxygen Concentration 0x08 Low Ambient Temperature 0x09 Low Purge Cell Voltage 0x0A Low Battery Voltage Startup Time Expired 0 0 Self Test Fault 0 0 General Software Fault OxOE Spurious Interrupt Fault The Nexa system has the following Warning Bitmap Codes 0x00 No Warnings 0x01 High Fuel Cell Stack Temperature Warning 0x02 Low Fuel Cell Stack Voltage Warning 0x04 High Fuel Cell Stack Current Warning 0x08 Low Fuel Pressure Warning 0x10 Fuel Leak Warning 0x20 Low Oxygen Concentration Warning 0x40 Low Purge Cell Voltage Warning These warning codes are designed so that more than one warning can be issued at one time The bitmap is a combination of the warn
110. ontaminant has any effect 1s not if a contaminant is present but how much Organic Contaminants Organic contaminants are carbon containing compounds of which there are thousands Almost all organics will adsorb on the catalyst if they can get to it This results in a loss in fuel cell performance due to a loss in platinum surface area Commercial Confidential 65 Nexa Power Module User s Manual BAL 2n an 5 Mechanical Interface 5100078 The most difficult issue in determining whether materials compatible is locating possible sources of organic contaminants In a fuel cell system the majority of organic contaminants come from plasticizers in polymers compressor oils lubricants on fittings and degradation of adhesives and seals It is difficult to determine if some organics are worse than others but smaller molecules i e plasticizers like phthalates would likely have a larger negative impact on fuel cell performance as they are more mobile than larger polymers Organic materials do not need water to move unlike anionic and cationic contaminants and can be transported by the gas itself depending on the volatility of the organic species Smaller molecules are generally more volatile than large molecules but volatility depends on the nature of the organic material Therefore when choosing plastics for use in a fuel cell system find materials that have either no plasticizers or very little Als
111. oroughly tested and passes for electromagnetic radiated emission limits tests as specified in the Federal Communications Commission Standard FCC15B without any external housing It is the responsibility of the integrator to ensure the final product which contains a Nexa power module passes appropriate FCC emission limit tests It is possible to couple electronic noise from Nexa components which are then radiated through OEM supplied components such as wires or metallic parts Design and routing of interface cables such as the main power connections battery power connections and control interface connections can also effect emission levels Cables should not be routed near the power supply sections of the control board It is possible for both the Nexa power module and the integrator supplied equipment to independently pass radiated emission limit tests but fail when packaged together The Nexa power module is also electromagnetically tolerant as will operate safely within the EMI environment as presented in the standards specified by UL991 Shock amp Vibration The Nexa power module has been designed and tested to withstand vibration loads described in the UL991 standard which applies to safety related controls employing solid state devices UL991 requires shaking the device from 10Hz to 60Hz at a constant displacement of 0 35mm and then a constant acceleration of 5g from 60Hz to 150Hz A total Commercial Confidential 86
112. ower TA Bn nverter Module Neutral 10 Ground Figure 29 Grounding of Power Leads Figure 30 illustrates the grounding scheme of the Nexa communications signals The Nexa control board is connected to the stack negative output terminal and therefore shares its potential Transmit and receive signals to and from the control board to the OEM controller or computer use the RS485 protocol To interface to a computer serial port these signal lines are converted to RS232 protocol The serial communication scheme of the Nexa module was designed for use with an OEM interface that shares the same ground as the Nexa control board as illustrated in Figure 29 When communicating to a computer particularly a desk top computer with a grounded power supply as shown in Figure 30 special care must be taken when considering grounding If the control board potential fuel cell negative terminal floats out of range with respect to earth ground gt 12V lt 7V ground currents can develop which will interfere with proper communications For this reason it is recommended that an optically isolated RS232 to RS485 converter be used when establishing communications to a laboratory computer The COM signal can be useful when integrating the Nexa communications to a computer or other serial device particularly if the external device is at a floating potential The COM signal ties the ground of an external device to the ground of the N
113. owing table lists the part numbers for each side of the connection Connector Name Nexa Connector OEM Connector Signal Interface Header AMP 638184 6 Ballard Designation J4 B Plug AMP 174514 1 Receptacle AMP 173716 1 Battery Connection Header AMP 643226 1 Ballard Designation J2 Plug AMP 350777 1 Male Terminal AMP 350922 3 Power Connection Ring Terminal AMP 2 321598 3 Ballard Designation 1 Stud 1 4 20 thread Table 24 Electrical Interface Connectors Commercial Confidential 72 Nexa Power Module User s Manual MAN5100078 BAL ARL 6 Electrical Interface 6 6 3 2 05 Grounding Figure 29 illustrates a recommended grounding methodology for Nexa end product integration In this example the end product is providing AC power through an inverter to a wall outlet The Nexa module positive and negative terminals provide power to the inverter which in turn provides hot and neutral connections to the wall outlet The enclosure chassis is connected to earth ground of the wall outlet and the fuel cell stack and inverter are allowed to float with respect to earth ground In Figure 29 the fuel cell negative output terminal is connected to chassis ground through a 10 kQ resistor to create a resistively grounded system and to prevent large voltage potential differences from ground Chassis Wall Outlet P
114. r and stored in a file for further assessment The power module s EEPROM stores the following information e EEPROM Header Data this contains factory information pertaining to the controller hardware and software e Fault Statistics this contains a record of the total number of each type of alarm e Configuration Data this contains oxygen and current sensor calibration data e Cumulative System Data Cell this contains overall lifetime and other cumulative information e Last Fault Status Data this contains detailed information pertaining to the last fault that occurred Data includes operating state settings system process variable data port configuration analogue to digital conversion values and time information e Historical Fault Data this contains information pertaining to the last 20 faults that have occurred This data is less detailed than the last fault status data Specific data includes operating state settings time information and system process variable data The historical fault data is accessed by clicking on a fault in the fault list see below 3 2 05 Commercial Confidential 46 Nexa Power Module User s Manual 5100078 BAL To retrieve the diagnostic data 1 Connect the computer to the Nexa module using the communication wiring harness as illustrated in the previous section 2 Start the NexaMon OEM software program 3 Provide 24VDC to the Nexa control
115. r is received The receive algorithm can be implemented in one of two ways Note that Receive Algorithm B is a simplification of Algorithm A Receive Algorithm A 1 When any character arrives on the serial interface put the character into the serial receive buffer 2 Ifthe received character is 0xCO call the SLIP decode routine passing it all the data currently in the receive buffer 3 Ifthe SLIP decode routine returns 0 then the decode operation failed This will happen if the receive buffer contained only the 0xCO character or if there was noise on the serial line and a byte stuffed SLIP character was dropped from the message 4 Ifthe SLIP decode routine returns a non zero value N then the first N 1 characters constitute the Nexa status message and the Nth character is the 8 bit checksum over the preceding N 1 characters Compute the checksum over the first N 1 characters and Commercial Confidential 83 Nexa Power Module User s Manual BAL 2n 5100078 an 7 Software and Communications compare it to the Nth octet If they match then the N 1 char status messages has been received intact If not discard the message 3 2 05 Commercial Confidential 84 Nexa Power Module User s Manual BAL 2n MAN5 100078 3 2 05 An 7 Software and Communications Receive Algorithm B 1 When any character arrives on the serial interface examine it to see if it is the SLIP End Character 0xCO
116. r module is rated for 1200 W net at a minimum nominal output voltage of 26 V The output power rating is for standard baseline operating conditions which are defined at sea level in ambient temperatures ranging from 3 C to 30 C The Nexa system is capable of operating at higher altitudes and in higher ambient temperature conditions but an appropriate power de rating factor must be applied Operating in high elevations reduces fuel cell performance output voltage by reducing the partial pressure of oxygen in the air Operation in high ambient temperature conditions also reduces system performance by increasing the parasitic load for stack cooling De rating curves for the Nexa power module are illustrated in Figure 40 The output power capacity of the Nexa system is de rated such that the minimal nominal output voltage remains 26 V As shown the rated output power is 1200 W net for sea level conditions between 3 C to 30 C The system power output capacity is de rated by 15 watts for every 100 meters above sea level At 2000 meters elevation the Nexa power module can provide 900 W net at 26 V The output power capacity is also de rated by 10 watts for every degree Celsius above 30 C up to a maximum of 40 C At sea level and 40 C the Nexa module is able to provide 1100 W net at 26 V 1200 1100 1000 Power Output Rating Watts 5 p p 500 1000 Ambient Temperature 25 4500 Altitud
117. r pump flow response however is vital to maintaining system performance during load changes Figure 39 illustrates the changes in output voltage stack current and airflow that accompany a step change in load At idle the oxidant airflow rate closely tracks the requested flow at about 16 slpm After a load step to full power 54 Agross the air pump rapidly speeds up to provide an airflow rate of about 85 slpm There is a brief 0 5 seconds undershoot 2 5 volts in stack voltage during this transient before the output voltage stabilises at 26 V Stack current also increases slightly during this transient interval due to increased parasitic power draw from the air compressor A similar transient interval occurs after a load step from full power to idle Airflow is gradually reduced due to inertia in the air pump Output voltage gradually recovers and stabilises to 43 volts over a 0 5 seconds interval 100 T 1 90 po ur 1 p 1 5 Stack V oltage Gross Current Requested Air Flow Actual Air Flow mm Stack Voltage Air Flow Gross Current Time Seconds Figure 39 Transient Response Characteristics 3 2 05 Commercial Confidential 97 Nexa Power Module User s Manual BAL 5100078 A 9 Performance Characteristics 9 8 Power De Rating Curves The Nexa powe
118. rasitic loads The automated Rejuvenation process lasts approximately 3 minutes All safety systems of the power module are available during the Rejuvenation process Note that a separate software state has not been designated for the Rejuvenation cycle During Rejuvenation the Nexa module broadcasts the Normal Shutdown stopping state message System Shutdown Procedure The System Shutdown Procedure is called in the following cases e In RUNNING or WARNING state when the Start line is deasserted after the stack has been running for less than 60 seconds e In STOPPING state after the stack has been running for more than 60 seconds and the 45 second purge is completed e In FAILURE state when the Start line is deasserted after a non leak fault or when the Start Line is deasserted after a H2 leak fault and the cooling fan has shutdown e When a self test or software fault is detected The System Shutdown Procedure stop the operation of the fuel cell system according to the following sequence The external load is disconnected The H2 fuel valves are all closed The purge valve is closed Internal loads are transferred from the stack to the battery The air pump is turned off The cooling fan is turned off If the shutdown was initiated due to a fault the failure data is recorded in the EEPROM If a non restartable fault occurs the non restartable status is written to the EEPROM If no faults have occurred the system returns to STAND
119. ring Transport when being transported Ambient Temperature Allowable range of ambient temperature 29 C to 70 C 3 2 05 Shock Loads During Transport The Nexa module and original packaging has been developed and tested according to the requirements of ISTA packaging standards test procedures 1A or 1B The OEM packaging must also be developed and tested in accordance with ISTA test procedure 1 or an equivalent industry packaging standard Drop and Topple The Nexa power module can withstand drop and topple abusive loads as described in the test methods of IEC publication 68 2 31 Drop and Topple Basic Environmental Testing Procedures Drop Test The Nexa power module can withstand a free fall from a height of 1 2m onto a hard surface concrete or steel Any failures directly or indirectly emanating from such a load condition shall not present a safety hazard Commercial Confidential Nexa Power Module User s Manual BAL i 2n N MAN5100078 Requirements Definition Description Quantity Storage Ambient Temperature Allowable range of ambient temperatures 29 C to 70 C Freezing Storage Allowable number of freeze thaw cycles 50 Cycles Relative Humidity Range of allowable ambient relative humidity 5 to 95 NOTES 1 The identified Original Packaging Assembly is to be used for all shipments of the Nexa power module Warranty returns of Nexa
120. ristics Performance characteristics of the Nexa power module are presented All performance data is given for baseline operating conditions defined at sea level and room ambient temperature Polarization Characteristics Figure 33 illustrates the beginning of life BOL polarization characteristics of the Nexa system Performance variability plus minus 2 sigma among systems is also indicated by the minimum and maximum expected performance Net output power ranges from zero at system idle to 1200 watts at rated power Net output current ranges from zero to 46 amps across the operating range of the power plant Output voltage varies with operating load according to the polarization characteristics of the fuel cell stack Normal idle voltages of the Nexa system are approximately 43 VDC At rated power the Nexa system output voltage ranges from 26 VDC to 29 VDC at beginning of life Commercial Confidential 90 Nexa Power Module User s Manual 5100078 BALLARD 3 2 05 Output Voltage Volts 9 Performance Characteristics 2000 1800 1600 1400 1200 1000 800 600 400 200 0 5 10 15 20 25 30 35 40 45 50 Net Current Amps 9 Net Voltage Gross Power Net Power Max Min 9 Parasitic Power Figure 33 Polarization and Power Curves Figure 33 also illustrates the system parasitic load as a function of net current and net output
121. rogen Tank Valve J4B4 Valve Hydrogen Tank Control Line M B3 Xu aa Valve Control Line Figure 27 Electrical Interface Diagram 3 2 05 Commercial Confidential 69 Nexa Power Module User s Manual BAL 2n MAN5 100078 6 1 6 1 1 3 2 05 An 6 Electrical Interface Power Connection The fuel cell power wires are 8 AWG wire and are terminated with Amp Ring Terminal Part 2 321598 3 suitable for connection to 1 4 posts The fuel cell power leads are illustrated in Figure 24 A relay and diode are required as shown in Figure 27 to prevent power draw from the fuel cell when it is not running and to prevent a backwards flow of current from integrated system sources such as a battery grid connection or capacitors into the fuel cell These two components must be installed on the OEM distribution board to ensure that all spark emitting components are in a separate chamber from the fuel cell Wires from the fuel cell control board will control the power relay as shown in Table 21 Actuator Description Operating Range Control Signal Signal Type Power Switch Relay 50 A continuous 13 5 VDC Digital low 50 VDC maximum 200 mA max side switch Table 21 Power Load Relay Specifications The Nexa module provides unregulated DC power Integration of power conditioning equipment may be required for supporting battery charging capability or to power AC loads Nominal
122. ry Power Removed Figure 32 Operating States 3 2 05 Commercial Confidential 75 Nexa Power Module User s Manual BAL i 2n N 7 Software and Communications 7 1 1 Off State 7 1 2 3 2 05 In the Off state no battery power is applied to the control board To progress to Standby battery power is applied to the control board causing a power on reset to occur Standby When entering Standby the control board will wake up power up the hydrogen sensor and begin continuously transmitting status messages to the OEM In Standby mode diagnostic commands can be sent to the control board to facilitate repairs or understand failures For the first 20 seconds after power up the hydrogen sensor needs to reach its operating temperature Until it does its reading is unreliable and falsely indicates a high hydrogen concentration Starting the fuel cell during this 20 second period is not possible if the hydrogen sensor is reading above 80 Pre Start Checks To start the fuel cell system from Standby the hardwired start line must be activated and kept activated When the start line is turned on the control program reads the restartability flag from the EEPROM If the system was last shutdown due to a non restartable fault hydrogen leak self test or software fault all subsequent start requests are ignored Otherwise the system verifies that the minimal startup conditions exis
123. s e Install a load relay on the positive output terminal of the fuel cell stack to prevent premature power draw from the Nexa module Connect the load relay control signal to the Nexa serial communication port as shown in Figure 5 Make sure to test the load relay is working properly before operating the system Refer to the Interface Specifications for connection details e Connect a blocking diode on the positive output terminal of the fuel cell stack as shown in Figure 5 to prevent applying reverse potential to the fuel cell stack by a battery or some other DC power module integration e Connect the positive and negative output terminals of the Nexa module to a DC load bank for providing a load during system testing e Provide a 5 V start signal to the Nexa serial communication port as shown in Figure 5 Refer to the Interface Specifications for connection details e Provide suitable water drainage for the oxidant air exhaust line e Connect the Nexa serial communication port to a computer through a RS485 to RS232 converter Refer to the Interface Specifications for the serial interface connection details e Develop interface software to read and log Nexa operational data transmitted through the serial message Refer to the Software Interface of the User s Manual for the messaging format and communication protocol specifications For new customers who may be unfamiliar with Nexa power module installation an
124. s data as measured by the Nexa power module controller All process variable values are logged when the logging feature is turned on whether they appear on the chart or not This data can be viewed in graphical form on the host computer Figure 15 illustrates how configure a data log file using NexaMon OEM e The Data Logging File field shows the name of the file that the data is being saved to e Period slider allows you to choose a data download interval of between 0 2 seconds and 10 minutes The one second interval is the default logging interval the first time NexaMon OEM is run The logging period is stored when NexaMon OEM is closed e Logging switch allows you to turn the data logging function on and off Click the Browse button to select a file name A dialogue box will appear which will allow you to enter the desired name and path for the stored data file The file is automatically saved in the comma separated variable CSV format and can be easily imported into a spreadsheet program such as Microsoft Excel To change the data logging filename or directory click the mouse cursor on the button right of the data logging name field You can then enter a new filename and or choose a different file path D File Serial Port TOOLS n i Sta Sto Air Pump J 0 Read EEPROM Set Restartable F9 EM z al EE Cooling Fan Start Stop J o a dy pid DATA LO
125. seconds and has a default range of two minutes Alter the range by selecting the rightmost or leftmost value and entering a new value Use the mouse to zoom in to an X axis location The Y axis represents the values of all the process variables The grey Y axis scale corresponds to the grey process variable fields and the black scale corresponds to the black process variable fields You can alter either scale by selecting either the top most or bottom most value and entering a new value Time Field The following time fields are displayed in the Main Screen of NexaMon OEM e System Runtime is the time since battery power was applied to the Nexa power module e System Lifetime is the total time that battery power has been applied to the Nexa power module e Stack Start Time is the time taken for the most recent startup of Nexa power module e Stack Stop Time is the time taken for the most recent shutdown of Nexa power module e Stack Runtime is the time since the Nexa power module was last successfully started or the total time the system was most recently run for e Stack Lifetime is the total time the Nexa power module has been in the running or warning states The format of all time fields 1s hh mm ss Commercial Confidential 41 Nexa Power Module User s Manual MAN5100078 BAL Installation 4 2 9 Data Logging The data logging facility provides real time sensor and statu
126. serial communications e Communications Wiring Harness complete with an RS232 to RS485 serial protocol converter as provided in the Installation Kit e Serial cable 9 pin female to 25 pin male as provided in the Installation Kit Program Installation To install the NexaMon OEM program insert the provided CD run the setup exe file and respond to the self install queries The software will be automatically installed onto the hard drive of your computer in the directory C Program Files NexaMon OEM To start the NexaMon OEM program double click on the Nexamon OEM exe file within Windows Explorer or select Start Programs NexaMon OEM NexaMon OEM from the Windows Start menu Alternatively create a shortcut of the executable file and move it to your desktop Double click on the icon to start the NexaMon OEM software To close the NexaMon OEM program click on the X in the top right hand corner of the main screen In order to establish effective communications with the Nexa module and computer the NexaMon OEM software must have control of the serial port Other devices such as PDA s may have software installed that also takes control of the serial port when in use and these devices can interfere with the NexaMon OEM communications Be aware of other software programs on your computer that utilise and configure the serial port and avoid conflicts with the NexaMon OEM software Commercial Confidential 36 Nexa Power Module
127. sions as a function of net output power Two curves are shown for operation at sea level One is for operation at room temperature and the other is for operation in 30 C ambient temperature Higher ambient temperature results in higher fan speed and greater overall noise emission The Nexa system produces approximately 65 dBA at 1 meter at rated output power operating at 30 C and sea level Higher noise emissions are possible at higher altitudes or higher ambient temperatures The maximum noise emission of the Nexa power module is 72 dBA at 1 meter 75 70 65 Fan and Air Pump for 21 C Sea Level average of 5 systems 8 Fan and Air Pump for 30 C Sea Level 1 system 60 Maximium Noise Level 100 Fan amp Air Pump 55 50 45 40 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 Ave Net Power Watts Figure 38 Noise Emissions at 1 Meter 96 Commercial Confidential Nexa Power Module User s Manual BAL 2n 1 i N DAP 9 Performance Characteristics 9 7 Transient Response Characteristics Transient response characteristics of the Nexa power module are shown in Figure 39 The graph illustrates the system s response to step changes in load The fuel cell stack immediately provides current to support a load step change The required hydrogen flow rate 1s supplied automatically by the regulator assembly provided sufficient fuel delivery pressure 1s maintained The ai
128. store fuel cell performance Commercial Confidential 39 Nexa Power Module User s Manual BAL 2n MAN5 100078 Installation 4 2 5 4 2 6 3 2 05 Status Lights The following status lights are displayed on the NexaMon OEM Main Screen The green Start Line light comes on when the start line has been activated The start line indicates that the Nexa power module has been signalled to start The green Cell Voltage Check light comes on when the voltages of the individual fuel cells are high enough for proper operation The red Serial Timeout light comes on when there is a problem with the serial inputs or outputs such as when the communications connector is unplugged or the data transfer is too slow The red Checksum Error light comes on when there is a checksum error in serial com munication from the Nexa power module indicating poor communications The Other Error light is for all other errors An error message will be displayed once but the error light will remain on as long as the problem persists Click Details to view more information about the error Process Variables The NexaMon OEM software monitors 17 key process parameters of the Nexa power module when the Communication Start Switch in the Main Screen has been toggled to the ON position During system operation the real time process values are indicated in the parameter field and the chart plots the progress of those variables that
129. t 1 The stack temperature is below 73 degrees Celcius 2 The H2 sensor is functioning properly and the measured H2 leak concentration is below 100 alarm 3 The O2 sensor is functioning properly and the measured O2 concentration is above 18 7 The ambient air temperature is above 3 degrees Celcius The battery voltage is above 18 volts If the above conditions are met then the system proceeds to the Starting State System Start up Starting State When the start line is applied and the startup conditions are met the system process with the following start up procedure 1 A signal is sent from the control board to open the external solenoid valves 2 The cooling fan is started and set to a duty cycle of 50 3 The air compressor is started up 1sec after the cooling fan 4 The main H2 solenoid valve is opened 5 The stack purge cycle is initiated The purge valve opens for sec and closes for Isec until the start up sequence is complete Commercial Confidential 76 5100078 Nexa Power Module User s Manual BAL 2n 3 2 05 An 7 Software and Communications 6 After 6 sec if the stack voltage is greater than 38V the purge cell voltage greater than 1 5V and the Cell Voltage Checker issues a PASS then the system transfers the internal loads from the battery to the stack Firmware revision 00 03 01 has lowered the Stack Voltage and the Purge Cell Voltage permissive limits to 30V and 0 8V respectively
130. t EEPROM Display y 2 SELFTI 3 LOw FUELP 4 SELFTEST FAULT 5 LOW FUEL P 6 SELFTEST FAULT 7 LOW FUEL P 8 LOW FUEL P 9 SOFTWARE FAULT 10 LOW BATTERY V 11 LOw BATTERY V 12 LOw BATTERY V 13 LOw BATTERY V 14 LOw BATTERY V 15 LOw BATTERY V 16 LOW BATTERY V 17 LOW FUEL P 18 LOW BATTERY V 19 LOW BATTERY V 20 LOW BATTERY V E gt Ed o amp Sp 8 a Ey 0 pem 3 aa omg 186 pci 6701 0 945 13 034 Figure 18 Sample of Historical Fault Data Screen 6 Press the CREATE FILE button or F2 to store the information to a diagnostic data report The program prompts you to select or enter a file name and directory A sample of the diagnostic data report is shown in Figure 19 7 Press the CLOSE button to return to the main screen 3 2 05 Commercial Confidential 48 Nexa Power Module User s Manual BAL 2n 5100078 Installation EPROM HEADER DATA Software Part Number 5 000 997 Software Revision ID 00 02 06 Software Build Date 2002 04 03 Software Flash CRC 16 0x9D34 Configuration Data CRC 16 0x78D0 EEPROM Header CRC 16 0 18 System Restartability Status NO FAILURE Factory Stack Lifetime Stamp 0016 39 02 Service Stack Lifetime Stamp 0017 16 03 Cumulative Time Cell Index 0 History Table Entry Index 7 Number of History Entries 20 CONFIGURATION DATA O2 Sensor Slope M 6 70 O2 S
131. t all times e Fuel cell operating parameters are continuously monitored to ensure they stay within desired limits These include fuel cell stack operating temperature fuel cell stack current output voltage and fuel supply pressure Warnings and shut down alarms are implemented on each of these parameters e A Cell Voltage Checker CVC system continuously monitors the operation and performance of individual cell pairs The presence of a failing cell will cause the Nexa system to shut down e A hydrogen leak detector is implemented within the fuel delivery subassembly Imbedded properly into the cooling air stream this sensor can also detect excessive hydrogen purge amounts or the presence of an external fuel leak in the fuel cell stack The Nexa system will shut down automatically if a hydrogen leak is detected e The Nexa power module comes equipped with an oxygen sensor for measuring ambient oxygen concentrations This feature prevents users from operating the Nexa power module in non ventilated areas where oxygen depletion may become a safety concern The power module shuts down automatically when low ambient oxygen concentration levels are measured In addition to warnings and alarms other safety features are included to the design of the Nexa power module A fuel shutoff solenoid valve closes whenever the power module is shut down This isolates the fuel supply and prevents hydrogen from entering the fuel cell stack
132. t may be caused by physical damage or seal failure The integration of the cooling system hydrogen leak detection warnings and alarms are an important element of the Nexa safety system design For this reason when performing packaging design it is recommended that the cooling fan intake draws some of its air from around the fuel cell stack thereby providing ventilation and leak detection to the fuel cell enclosure The Nexa power module cooling air exhaust specifications are shown in the table below The maximum cooling airflow rate required for maintaining desired stack operating temperature at full power is 3600 slpm In order to assure that the cooling fan can deliver the needed airflow the OEM must limit the flow restriction to the fan intake and exhaust At maximum cooling airflow rate a pressure loss of 1 4 inches of water is available to the OEM for performing ducting and grill geometry design Requirement Description Quantity Coolant Type Ambient air Pressure Atmospheric 1 atm Temperature Cooling air outlet temperature at rated 17 C above load and operating temperature ambient Flow Rate Maximum required cooling air flow rate 3600 slpm 140 scfm Coolant Outlet Restriction Maximum allowable pressure loss in 1 4 inches of OEM system design ducting grill water geometry etc at maximum cooling air flow rate Table 18 Cooling Air Exhaust Specifications Commercial Confidential 62 Ne
133. t prior to shipping the end product e Testing of the end product incorporating the component Nexa will be necessary to determine of the shutdown system controls will operate as designed in the complete product Review of the test cell conditions in which shutdowns occurred due to oxygen depletion or hydrogen leakage an abnormal situation need to be conducted It will not be necessary to repeat all the test cell conditions but review of the end product attributes will allow consideration of worst case scenarios Consideration should be made to include one or two oxygen depletion scenarios while instrumenting the room for oxygen content two or more hydrogen leak scenarios to address a leak within the end product enclosure and a leak that may propagate from the end product and into the test cell room e The fuel connection made to the Nexa power module will be investigated per the applicable end product standard Requirements for total system shutdown as a result of various abnormal conditions suggest two safety valves or other configuration e The Nexa power module shall be implemented in the end product as per the manufacturer s User s Manual Special consideration should be paid to the parameters for operation transportation and storage 3 2 05 Commercial Confidential 89 5100078 Nexa Power Module User s Manual BAL 2n 9 9 1 3 2 05 AN 9 Performance Characteristics Performance Characte
134. tegrator comments and opportunity for modifying operation or interface conditions in order to alleviate the alarm condition On the other hand the Nexa system is immediately shut down when failure limits are exceeded The following table shows the warning and failure levels used by the fuel cell system Parameter Warning Level Failure Level Restartable Commercial Confidential 101 Nexa Power Module User s Manual MAN5100078 BALLARD Planned Fuel Cell Stack Temperature gt 71 C gt 73 C Yes Fuel Cell Stack Voltage lt 23 Volts lt 18 Volts Yes Fuel Cell Stack Current gt 60 Amps gt 70 Amps Yes Firmware Revision 00 03 01 gt 65 Amps gt 75 Amps Yes Cell Voltage Checker N A 0 85 V cell pair Yes Hydrogen Pressure lt 1 0 barg lt 0 5 barg Yes Hydrogen Concentration 80 100 10 000 ppm No Oxygen Concentration lt 19 2 lt 18 7 Yes Ambient Temperature N A lt 3 start up Yes Battery Voltage N A lt 18 Volts start up Yes Purge Cell Voltage lt 1 0 Volts lt 0 8 Volts Yes Firmware Revision 00 03 01 lt 0 8 Volts 0 7 Volts Yes System Time out during Start up N A Digital Yes Self Test Fault N A Digital No Software Fault N A Digital No Table 27 Warning and Failure Alarm Limits Non restartable Faults Certain Nexa system failures are considered non restartable After a non restartable fault has occurred th
135. temperature conditions e Freeze thaw cycling Operating continuously at full power over its lifetime the Nexa module output performance degrades at a rate of about 0 54 mV hour As a result after 1500 hours of continuous operation at 46A net the system output voltage is expected to lose approximately 0 8V Under fixed current conditions this translates into a power loss of about 37W Note that additional power can be drawn from the Nexa module to compensate for this loss by further increasing the output current of the system Operating continuously under part load conditions lt 35A the Nexa module exhibits essentially zero degradation There has been no observed decay in voltage output over the system lifetime when operating under steady state part load conditions The impact of dynamic loads on system lifetime and performance degradation has also been evaluated over 1500 hours of continuous operation A variety of load profiles have been tested including instantaneous load changes between idle and full power Essentially zero output voltage degradation was witnessed under dynamic load test conditions In addition to continuous steady state and dynamic loads the Nexa module has been evaluated for its on off cycling ability The module is capable of executing 500 cycles between the off state and full power operation as detailed in the product specification Over Commercial Confidential 99 Nexa Power Module User s Man
136. th required system inputs for operation Please note that the Product Specification does not address the following considerations The Warranty period is defined by the Sales Agreement gt Outdoor applications for the Nexa module were not evaluated under UL component recognition Beginning of Life Within the first 40 hours of module operation within 90 days of receipt BOL from Ballard End of Life EOL Characterised by performance below 22V or a non repairable fuel cell stack failure Cold Start The temperature of the entire Nexa power module is at equilibrium with the ambient air temperature Indoors or Outdoors Any location where the Nexa power module is protected by the end product outer enclosure against wet marine freezing or other inclement conditions and against sand dust or other particulates Uninstalled Not installed into an enclosure nor integrated with an external thermal management system fuel supply system or power conditioning system Standard Conditions Evaluated at sea level at an ambient cooling air and oxidant air temperature of 30 C Voltage at Rated Power Measured as the minimum 60 second running average within the first 30 minutes of continuous use At time of module shipment Rated Power and Voltage will be within 5 of listed specifications Table 3 Nexa Product Specification Definitions Commercial Confidential 11 Nexa Power Module User s Manual
137. ual BAL 2n an 9 Performance Characteristics 5100078 the course of on off cycling Nexa module output performance degrades at a rate of about 1 1 mV cycle Over 500 cycles the system output voltage is expected to lose approximately 0 56V Operation Conditions Degradation Rate Period Losses Steady State Full Power 46 25 mW hr 1500 hours 37 W 0 54 mV hr 0 8 V Part Load lt 35 Anet 0 mW hr 1500 hours 0 W 0 mV hr 0V Dynamic Loads Idle to full power 0 mW hr 1500 hours 0 W 0 mV hr 0V On Off Off 46 A net 52 mW cycle 500 cycles 26W 1 1 mV cycle 0 56 V Storage Hours 20 C 5 RH 8 mW hr 1 month 5 5 0 17 mV hr 0 12 V 20 5 25 mW hr 1 month 18 W 0 56 mV hr 0 4 V Freeze Thaw 20 C to 40 C 1 0 W cycle 50 cycles 50 W 23 mV cycle 1 1 V Table 26 Lifetime Characteristics Storage losses for the Nexa power module have been evaluated under both freezing and above freezing conditions after several months of storage Table 26 normalises the storage loss on a per month basis Freezing storage conditions induce very little performance degradation in the Nexa module Higher storage temperatures accelerate the storage loss of the unit Under typical room temperature conditions the Nexa module loses about 0 4V per month of storage The rate of storage loss gradually declines over time with an anticipated floor
138. ue to storage Furthermore modules which are exercised frequently or for long periods will not encounter this performance loss Ballard has developed an automated onboard recovery procedure for the Nexa power module which has been implemented in firmware revision 00 03 01 An extended shut down sequence has been added for specific maintenance intervals which incorporates an automated rejuvenation process to offset the performance losses due to prolonged storage In addition start up permissive limits shut down limits and warning levels have been modified to increase availability and extend system performance Customers are encouraged to upgrade their Nexa units with the latest firmware revision 00 03 01 In order to assure peak performance of the Nexa power module exercise the system every 2 3 months To initiate the automated rejuvenation process operate the Nexa module at approximately half load for between 10 and 30 minutes If the required operating conditions are met the Nexa module will automatically execute the recovery process as part of an extended shut down sequence The extended shut down sequence used for this periodic exercising or maintenance interval lasts approximately 4 minutes Contact Ballard Customer Service for details The internal conditions for executing the automated rejuvenation process are 1 the SYSTEM RUN TIME measured by the onboard controller must be between 10 and 30 minutes
139. uel system Contact Ballard Field Service for further support 105 Nexa Power Module User s Manual MAN5100078 DESCRIPTION OF WARNING OR FAILURE BALLARD POSSIBLE CAUSE Purge valve failed open Cooling fan motor is failing or has failed External fuel cell stack leak Time Out on System Start Up CVC system is not properly assembled and plugged in Solenoid valve is not opening Purge valve is not opening Stack voltage is too low Non Operating Performance Loss NOPL or fuel cell contamination air or fuel supply Load relay closed and system is starting under load Software Faults Confirm non restartable fault using diagnostic software Sensors unplugged or out of range H2 O2 P T I Loose wiring harness connection to the control board Software control board failure Table 28 Troubleshooting Checklist 3 2 05 Commercial Confidential Planned SUGGESTED ACTION Listen for audible clicking of the purge valve during system operation Contact Ballard Field Service for further support Perform audio visual inspection of fan and motor Call Ballard Field Service for further support Contact Ballard Field Service for further support Check CVC fingers are making proper connection with plates Check cable connections Measure and confirm 12 V signal is applied to the solenoid Listen for solenoid clicking Call Ballard Field Service for detailed dia
140. uence to ensure proper water management upon storage In the first 10 seconds The external load relay is disconnected The cooling fan is set to idle to cool the stack The purge valve is opened to rid the stack of contaminating gases PO The air pump is set to 70 duty cycle to flush the stack of residual water During the next 5 seconds 1 Stack power is disconnected 2 H2 solenoid valve are closed 3 Purge valve is closed The cooling fan is stopped 15 seconds after the Start signal is removed The air pump continues to operate until 45 seconds has expired and the system returns to the Standby state Commercial Confidential 77 Nexa Power Module User s Manual BAL 2n MAN5 100078 7 1 6 1 7 1 7 3 2 05 AN 7 Software and Communications If an emergency or rapid shut down is required by the Nexa system the start line should be turned off and battery power removed returning the system immediately to the Off state Rejuvenation firmware revisions 00 03 01 or greater The Rejuvenation sequence is performed prior to the Normal Shutdown if the Nexa module has been running for between 10 30 minutes at an average gross stack power of 200W or greater measured over the last 10 minutes of operation The Rejuvenation process restores fuel cell stack performance that may have been degraded by prolonged storage or certain contaminants by repeatedly cycling stack voltage under the presence of internal pa
141. uestions Figure 1 The Nexa Power Module Commercial Confidential 1 Nexa Power Module User s Manual 5100078 BALLARD 1 Introduction 1 1 General Description The Nexa power module is a fully integrated system that produces unregulated DC power from a supply of hydrogen and air It contains a BALLARD fuel cell stack as well as all the ancillary equipment necessary for fuel cell operation Ancillary subsystems include hydrogen delivery oxidant air supply and cooling air supply Onboard sensors monitor system performance and the control board and microprocessor fully automate operation The Nexa system also incorporates operational safety systems for indoor operation Figure 2 illustrates the Nexa system schematic The diagram also shows the Nexa system boundary and important interface connections to the DC module Hydrogen oxidant air and cooling air must be supplied to the unit as shown in Figure 2 Exhaust air product water and coolant exhaust is emitted The Nexa power module produces unregulated DC power for interfacing with external power conditioning equipment Battery power must be supplied for start up and shut down requirements Finally a communications interface must be provided to the Nexa unit for providing start stop signals and for receiving serial port communications lt Control Signals 1 7 dim Controller Evaporator Temperature Pr
142. ulator must be installed on the hydrogen storage bottle to reduce the fuel delivery pressure to the Nexa module Refer to the Interface Specifications for the range of allowable hydrogen delivery pressures e 24V Power Supply or battery Refer to Interface Specifications for power requirements during system start up e DC load bank Maximum continuous power demand of 1200W e 16mm OD Tube approximately 6 The process air exhaust tube interfaces to the base of the humidity exchanger for collecting product water from the fuel cell reaction Bucket for Collection of Product Water The Nexa module produces roughly 790ml hour of product water at full power e Laptop Computer Refer to the computer hardware requirements for the Ballard monitoring and diagnostic software presented in the following section Figure 7 Nexa Laboratory Test Set up 3 2 05 Commercial Confidential 32 Nexa Power Module User s Manual 5100078 BAL Installation 4 1 1 Installing the System Tray Figure 8 illustrates how the Nexa module is installed in the system tray Ensure that the Nexa system s feet are properly installed in the tray s mounting pads to prevent damage to the control board lt z 3 gt Figure 8 Installing the Nexa System Tray 4 1 2 Connecting the 24V Power Supply Figure 9 illustrates the power supply connection to the Nexa control
143. until it is cleared using the diagnostic software features provided by NexaMon OEM with the assistance of Ballard Customer Service Failure Status Field Indicates the kind of failure that has occurred after the Nexa module has been put into the Failure State Types of failures include High Stack Temperature Low Stack Voltage High Stack Current Low Cell Voltage Low Fuel Pressure Fuel Leak Low Oxygen Concentration Low Air Temperature Low Purge Cell Low Battery Voltage Start Commercial Confidential 38 Nexa Power Module User s Manual 5100078 BAL Installation 3 2 05 Time Expired Self Test Fault and Software Fault Refer to Table 14 for the failure alarm limits of the Nexa power module The latest firmware revision 00 03 01 incorporates modified alarm limits to increase availability and extend system operation Warning Status Field Indicates the kind of warning that is occurring when the Nexa module is in the Warning State Types of warnings include Stack Temperature Stack Voltage Stack Current Fuel Pressure Fuel Leak Oxygen Concentration and Purge Cell Voltage Warning Multiple warnings can be displayed concurrently Refer to Table 14 for the warning alarm limits of the Nexa power module The latest firmware revision 00 03 01 incorporates modified warning limits to improve product robustness Parameter Warning Level Failure Level
144. ure low fuel pressure or hydrogen leak detection Do not operate the Nexa power module on a grade of more than 45 degrees e Do not connect or disconnect power cables when the fuel cell module is energised e Do not dismantle the Nexa system Contact Ballard if you have any concerns about operation Using Hydrogen WARNING FIRE OR EXPLOSION Keep all sources of ignition away from hydrogen This unit uses hydrogen fuel Hydrogen is a colourless odourless and flammable substance It is highly combustible in the presence of oxygen and burns with a colourless flame Leaking gas may be hot and pose a burn danger Stop the flow of gas if you are not in danger and use water to cool the area If fire occurs do not attempt to extinguish flames allow the fire to burn out Prevent overexposure to hydrogen Hydrogen is non toxic but can act as a simple asphyxiant by displacing the oxygen in the air There are no warnings before unconsciousness results When operating the Nexa power module in an enclosure e Ensure ventilation slots are clear and unobstructed at all times during operation e Operate within the temperatures limits stated on the Nexa system nameplate e Never operate if an alarm condition exists Commercial Confidential 23 Nexa Power Module User s Manual BALLARD MANS5 100078 3 2 1 3 2 2 3 2 05 Handling Compressed Gas Cylinders WARNING Do not handle compressed
145. urs Humidity Exchanger Replace 800 Hours Exercise Rejuvenation The Nexa module firmware revisions 00 03 01 or greater incorporates an automated rejuvenation process which corrects for storage losses and recovers system performance upon shutdown To maintain peak performance it is recommended that customers exercise their Nexa modules every 2 3 months to initiate this rejuvenation process Refer to Section 7 1 6 1 for details on the rejuvenation process Air Filter The Nexa air filter requires replacement every 500 hours or as required depending on operating environment Humidity Exchanger The Nexa module incorporates a humidity exchanger that requires replacement after 800 operating hours This repair should be conducted by an authorized service provider Trouble Shooting This troubleshooting guide provides useful information for interpreting and diagnosing Nexa system alarms and shutdowns Warning and failure limits are given along with description of non re startable faults that may occur during Nexa system operation An easy to follow troubleshooting checklist is also provided to assist with interpreting failure alarm readings and determine possible causes Warning amp Failure Levels The Nexa power module issues warnings when certain performance parameters fall outside of a pre defined range Warnings are not a requirement for shut down They are intended however to provide the system in
146. used for integration with metal hydrides for evolving hydrogen Hot air may also be used for space heating in some cases The cooling system is also used to dilute hydrogen that is purposely purged from the Nexa module during normal operation Hydrogen is released into the cooling air stream by way of the purge solenoid valve as shown in Figure 2 The hydrogen quickly diffuses into the cooling air and is diluted to levels far below the Lower Flammability Limit LFL of hydrogen For safety a hydrogen sensor is located within the cooling air outlet stream and provides feedback to the control system The control system generates warning and alarm signals if the hydrogen concentration approaches 25 of the LFL The Lower Flammability Limit LFL of hydrogen is the smallest amount of hydrogen that will support a self propagating flame when mixed with air and ignited At concentrations less than the LFL there is insufficient fuel present to support combustion The LFL of hydrogen is 4 by volume 3 2 05 Commercial Confidential 5 Nexa Power Module User s Manual 5100078 BALLARD 1 Introduction er 3 2 05 Electronic Control System Nexa system operation is automated by an electronic control system The control board receives various input signals from onboard sensors Input signals to the control board include fuel cell stack temperature hydrogen pressure hydrogen leak concentrations fuel cell stac
147. waste heat are generated by the fuel cell system Most of this heat is available in the cooling air stream for thermal integration purposes 1800 1600 1400 1200 1000 800 600 400 200 0 5 10 15 20 25 30 35 40 45 50 Net Current Amps Heat Production 7 Net Power Figure 36 Heat Production Rates Commercial Confidential 94 Nexa Power Module User s Manual 5100078 9 5 3 2 05 Water Production Water Production Liters Hour Figure 37 illustrates the beginning of life BOL Nexa system water production as a AN 9 Performance Characteristics function of net output current and average net output power Approximately 870 ml hour of water is produced by the fuel cells at rated power either as vapour or liquid As shown in Figure 37 water production is nearly proportional to net output current 1 000 0 900 0 800 0 700 0 600 0 500 0 400 0 300 0 200 0 100 0 000 Figure 37 Water Production Rates 15 20 25 30 35 Net Current Amps Water Production Commercial Confidential Net Power 40 45 50 1500 1350 1200 1050 900 750 600 450 300 150 95 Power Watts Nexa Power Module User s Manual BAL 2n 5100078 iti 9 Performance Characteristics 9 6 3 2 05 Noise Level dBA Noise Emissions Figure 38 illustrates the beginning of life BOL Nexa system noise emis
148. xa Component Layout and Interfaces Hydrogen Inlet The hydrogen inlet draws hydrogen from the fuel storage containers for use in the fuel cell power reaction Specifications for the hydrogen inlet connection are provided in NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning at a higher pressure than the minimum supply pressure see Table 25 for warning and shut down values Table 6 The Nexa fuel cell system is designed for operation on pure gaseous hydrogen No fuel humidification is required Hydrogen can be supplied at pressures ranging from 70 to 1720 kPa g 10 to 250 psig A pressure relief valve is located on the fuel assembly immediately upstream of the fuel regulator The relief valve vents at 2400 kPa g 350 psig to ensure overpressure conditions are not applied to the downstream pressure regulator assembly The relief valve discharges into the vicinity of the onboard hydrogen leak detector thereby shutting down the system in the event of excessive inlet supply pressure NOTE 1 Refers to pressure supplied to the Nexa inlet during operation Depending on the users fuel supply design pressure will droop below the user s regulator set point due to losses from fuel flow Also note that there will be a low fuel pressure warning
149. xa Power Module User s Manual BAL 2n MAN5 100078 5 5 5 6 3 2 05 An 5 Mechanical Interface Product Water At full power the Nexa power module produces 870ml hr of water In theory water produced by the cathode of a fuel cell is pure and free of contaminants However certain chemical species which exist in air quickly dissolve in the water as it travels through the cathode flow fields in contact with air As a result the conductivity of the product water is generally greater than the conductivity of pure water Although the conductivity varies according to the operating and environmental conditions the conductivity of water has been measured to be in the range of 5 to 10 pS In approximately the first 100 hrs of operation the OEM may notice tiny black particulate in the product water These particulate are generally silicones or silicates arising the high volume manufacturing processes employed to manufacture the electrodes and flow field plates Contaminants PEM fuel cells are susceptible to contaminants in the fuel and air Contamination typically manifests as a drop in fuel cell output voltage In most cases the effect 1s reversible through operation once the source of contamination has been removed However in some cases the damage is permanent Carbon monoxide sulphur compounds and hydrocarbons are the principal fuel contaminants in PEM fuel cell systems The Hydrogen Supply Interface section of this
150. zard and they automatically vent and or depressurise when the module is shut down Hydrogen pressure feeding the power module may reach 17 barg 2400 kPa g and will typically remain pressurised even when the module is shut down This high pressure is potentially dangerous Use caution and ensure that the circuit is de pressurised prior to access WARNING Ensure gas circuits are depressurised prior to access Do not loosen fittings while under pressure Doing so may result in uncontrolled gas release Rotating Equipment The Nexa power module contains a process air pump and a cooling air fan that contains rotating parts During normal operation the air pump is enclosed within the module ductwork whereas the fan is partially exposed Take care to avoid contact with rotating equipment especially if protective enclosures have been removed to facilitate maintenance Loose clothing may become entrained in rotating equipment and should not be worn WARNING Do not wear loose clothing while operating the NexaTM power module Do not remove protective enclosures Commercial Confidential 28 Nexa Power Module User s Manual MAN5100078 BALLARD 4 Installation Figure 5 illustrates the basic installation of a Nexa power module in the lab and the mechanical electrical and software interfaces necessary for operation Before getting started ensure that the following test lab criteria and installation procedures

NexaTM Power Module User's Manual MAN5100078

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