Product User Manual EPRI Commercial Microwave Fabric Dryer
Contents
1. The sensors operate by passing a current through a selective adsorbent element whose resistance varies as compounds are adsorbed The output voltage varies with this resistance and increases as compounds are adsorbed The microprocessor monitors the output voltage and triggers the gas sensor fault cycle see Basic Operation section when its slope exceeds a preset value The sensor elements operate most effectively at an elevated temperature thus a heater voltage 5 VDC is supplied in addition to an instrument voltage 10 VDC These voltages are supplied whenever line power is connected to the CMFD and the main circuit breaker is turned on A warm up period of up to one hour is required for stable and reliable operation of the sensors Magnetron Thermal Cutouts Each magnetron is protected from overheating by a thermal cutout switch device mounted to its side Each thermal cutout is connected in series with the coil of the contactor that turns on the respective magnetron power supply If a magnetron overheats then its associated cutout opens and turns off only the power supply to that magnetron Since the blower continues to operate the magnetron will cool down until the thermal cutout resets and turns the power supply back on Sensor Lint Screen Burn off To protect the exhaust gas sensors from fouling due to lint accumulation a lint screen separates the sensors from the flow of air in the exhaust duct But if lint is allowed to2. e Regular This cycle combines microwave energy with conventional hot air During the drying stage all three microwave power supplies are on while two of the three duct heaters are on The final stage of the drying cycle is a three minute cool down period during which the microwave supplies and duct heaters are all turned off e Delicate This cycle utilizes only microwave energy to provide the lowest temperature drying of the three cycles Heated air is provided only by the waste energy that is dissipated by and salvaged from the microwave power supplies As with the other cycles the final stage is a three minute cool down period during which all microwave supplies and duct heaters are turned off Close the dryer door and press the Start button to begin the drying cycle The basket will immediately begin to rotate and the main blower will operate Approximately five seconds later the microwave power supplies will be turned on as can be verified by the clack of the associates contactors Failure to start properly will usually be due to one the following e An interlock is not satisfied in which case the buzzer will immediately sound for ten seconds see general fault cycle described below Check to be sure the door is closed tightly and all covers are in place then try again e One or more gas sensors have caused a fault condition in which case the basket and blower will operate but the clack of Gerling Applied
3. Product User Manual EPRI Commercial Microwave Fabric Dryer Document 930001 Rev 2 July 1999 G A IE GERLING APPLIED Cup YAN ENGINEERING INC P O Box 580816 Modesto CA 95358 Product User Manual Page 2 EPRI Commercial Microwave Fabric Dryer REVISION HISTORY REV DESCRIPTION DATE APPROVAL 1 DOCUMENT WAS NUMBER ON10051 27MAR99 JEG 2 ADDED CYCLE TIMER 23JUL99 JFG WARRANTY Products manufactured and sold by Gerling Applied Engineering Inc GAE are warranted to be free of defects in materials and workmanship under normal use and service for a period of twelve 12 months from the date of original shipment GAE s obligation under this warranty is limited to repairing or replacing at GAE s option all non consumable component parts Consumable parts are specifically excluded from this warranty and may include but are not be limited to magnetrons fuses lamps seals o rings v belts and fluids All warranty repairs are to be done at GAE s facility or as otherwise authorized by GAE All shipping charges for warranty repair or replacement are the purchaser s responsibility unless otherwise agreed to by GAE This warranty supercedes all other warranties expressed or implied No warranty is given covering the product for any particular purpose other than as covered by the applicable product specifications GAE assumes no liabili
4. As the basket rotates and the fabrics tumble inside the dryer cavity the electric field pattern is constantly changing Thus the electric field seen by the field strength sensor is constantly changing and results in wide variations of the output signal The peak values typically remain well below the setpoint values at the beginning of the drying cycle but towards the end of the cycle they can easily exceed the setpoint values while the more important time averaged value is still below the setpoint To help compensate for these variations the microprocessor calculates the average value of the 25 most recent field strength readings and uses the result for the interlock function Electrical arcing can occur inside the dryer cavity under certain conditions typically when loose metal objects are present and the electric field strength is high Arcs can result in scorching of fabrics and possibly an open flame if allowed to continue unchecked Arcs are detected using a photo diode that generates a small voltage proportional to the amount of light inside the dryer cavity The duration of an arc is usually very short so the detector circuitry amplifies the signal pulse and stretches it sufficiently to energize a relay and shut down the CMFD When this occurs the Arc Detect lamp on the front panel turns on to notify the operator of the event The operator must then reset the CMFD by pressing the Stop button NOTE During testing of
5. are required Gerling Applied Engineering Inc Modesto CA Product User Manual Page 7 EPRI Commercial Microwave Fabric Dryer Electrical Specifications Microwave Power Magnetrons Hot Air Line Power Input Mechanical Specifications Basket Size Basket Capacity Door Opening Exhaust Duct Free Air Displacement Overall Dimensions Weight approx Controls Cycle Start Cycle Stop Cycle Select Dryness Fault Indicators Cycle Timer Sensors Dryer Operation Thermal Cut outs Safety 5 4 KW nominal provided by three 1 8 KW generators Hitachi 2M130 6 5 KW approx provided by three 1 5 kW duct heaters plus 2 kW from recycled waste heat 208 220 VAC Single Phase 60 Amps 2 wire plus ground 26 diameter x 20 deep 12 Pounds dry weight 100 moisture retention 16 Wide x 10 High 4 Diameter 175 CFM approximate 30 High x 36 Deep x 62 High 700 lb net 960 Ib shipping Pushbutton Pushbutton 3 position rotary switch for Regular and Delicate settings Permanent Press setting has been disabled Disabled Check Load Arc Detect Programmable timer initiates End of cycle routine upon time out Exhaust air thermostat exhaust air relative humidity exhaust air temperature Moisture contact sensor has been disabled Magnetrons 3 duct heaters 3 exhaust air Door interlock switches microwave field strength detec
6. Engineering Inc Modesto CA Product User Manual Page 12 EPRI Commercial Microwave Fabric Dryer m Cycle Stop k the microwave power supply contactors will not be heard see gas sensor fault cycle described below Try starting again after the end of the fault sequence ten second buzzer turns off but discontinue starting and check the load if the fault cycle is repeated NOTE When starting the drying cycle for the first time following initial power up see above the gas sensor fault cycle see below may be initiated due to insufficient warm up of the gas sensors This should not occur during subsequent starts unless line power is turned off and then back on again Once started the drying cycle will continue until one of the following occurs e The cycle ends normally when moisture has been sufficiently removed The buzzer will sound for two seconds to indicate the normal end of cycle e The Stop button or the door switch may be pressed to stop the drying cycle at any time and for any reason This action initiates the fault cycle during which the buzzer will sound for ten seconds e A fault condition as explain below will stop the drying cycle automatically The drying cycle can be restarted following any of the above stop events once the buzzer has sounded WARNING Fabrics may be hot due to heated moisture during the drying cycle and can cause severe burns if improperly handled The operator must exe
7. Schematic Diagram Comm Mw Fabric Dryer Drawing 910049 Schematic Diagram Microprocessor Interface Drawing 910050 Line Power Distribution Diagram Gerling Applied Engineering Inc Modesto CA Product User Manual Page 5 EPRI Commercial Microwave Fabric Dryer INTRODUCTION The EPRI Commercial Microwave Fabric Dryer CMFD was designed and constructed by AGL Inc under contract from the Electric Power Research Institute for the purpose of on site demonstration and evaluation of the microwave fabric drying process However prior to completion of construction of the CMFD the contract was terminated with AGL and funding for the dryer development program at EPRI was temporarily halted During its hiatus the dryer program was transferred to GAE Inc to await funding for completion of construction and general refurbishment of the CMFD Renewed interest in the program focused around potential industrial applications in textiles manufacturing A contract was awarded to GAE to complete the dryer s construction and deliver it for on site installation and operation While most of the dryer s original functionality remains intact certain functions and features have been altered or deleted from the original design specification due to discrepancies or conflicts in their operation Some of these alterations were necessitated because of insufficient time and or funding in the current program to adequately resolve the issues while o
8. free With the exception of the lint screen there are no operator serviceable parts or subassemblies inside the CMFD WARNING Lethal voltages may exist inside the CMFD even A during periods of non operation All service personnel must be aware of the hazards involved with high voltage electrical circuitry and high power microwave devices In the event service becomes necessary all repairs should be performed by a qualified service technician Lint Screen Cleaning The lint screen located inside the panel beneath the cavity door should be inspected regularly and cleaned as necessary Failure to properly clean the lint screen may result in inadequate air flow and faulty operation of the CMFD Gerling Applied Engineering Inc Modesto CA Product User Manual Page 21 EPRI Commercial Microwave Fabric Dryer PROCESS DATA COLLECTION The microprocessor controlling the CMFD is provided with a dedicated serial port B which can be used to send information processed by the microprocessor to a remote data acquisition system A ribbon cable terminated with a 9 pin subminiature D type connector is provided at the back of the CMFD for this purpose The microprocessor control software is designed to deliver the following parameters through this serial port e Exhaust Temperature e Exhaust Relative Humidity e Microwave Field Strength A typical IBM compatible personal computer can be used to collect the data delivered by
9. of sensors to optimize performance and ensure safety The microwave energy is supplied by three separate 1 8 kW generators for a total microwave power input of 5 4 kW Hot air is provided by three separate 1 5 kW duct heaters Energy efficiency is maximized by recycling the waste heat from the microwave generators and other heat producing electronics providing a total hot air capacity of approximately 6 5 kW Selectable drying cycles include Regular and Delicate the Dryness selector has been disabled The Regular drying cycle combines microwave energy with hot air and cuts the drying time to 1 3 that of conventional dryers The Delicate cycle eliminates hot air altogether and uses only microwave to provide the lowest temperature drying The CMFD includes state of the art safety features to protect both the dryer and operator from improper operation and use A variety of sensors are provided to detect the presence of improper materials in the drying load and shut off the dryer An indicator is provided on the control panel to warn the operator to check the load Additional sensors are provided to monitor the dryer operation and performance and shut off the dryer in the event of malfunction Facilities requirements for the CMFD are the same as those for conventional commercial dryers The input line power required is 208 220 VAC single phase 60 Amps and the exhaust connection is to a standard 4 diameter duct No cooling or gas connections
10. the c uwave subdirectory and the WinWedge software and associated configuration file uwave sw3 must reside in the c Program Files winwedge subdirectory so they can be located by the Excel spread sheet Gerling Applied Engineering Inc Modesto CA
11. the CMFD the arc detector was causing numerous false shut downs due to electrical interference from other circuitry within the CMFD A significant amount of time was spent trying to isolate and correct the problem but no solution was found the would prevent such nuisance tripping As a result the arc detect circuit was temporarily disabled However it was decided that the presence of the field strength and gas sensors will adequately protect the operator from harm and CMFD from damage in the event that arcing occurs inside the dryer cavity Exhaust Humidity Sensor The relative humidity of the exhaust air is measured using a sensor whose output voltage is proportional to relative humidity and calibrated in percent RH This signal currently is not used actively Gerling Applied Engineering Inc Modesto CA Product User Manual Page 17 EPRI Commercial Microwave Fabric Dryer by the microprocessor for control of the CMFD but rather it is provided only for data acquisition purposes Exhaust Gas Sensors A series of four sensors monitor the exhaust air for the presence of specific compounds commonly found in smoke or other products of combustion Each sensor is designed to detect a different set of compounds as defined in the following chart Gas Sensor Compound Sensitivity Sensor Number Figaro Type Compounds Detected 1 822 Toluene 2 825 Hydrogen Sulfide 3 842 Methane Propane Butane 4 882 Alcohol
12. the microprocessor The serial port on the computer is used to collect the data and should be setup as follows COM 1 19 200 baud No parity 8 data bits 1 stop bit No handshaking Terminal Emulator Data Logging Any terminal emulation program such as HyperTerminal provided with MS Windows 95 can be used to directly read the last values sent by the microwave dryer CPU The serial string received will be a comma delimited ASCII string currently configured to send the last sampled temperature humidity and field strength values The typical string will be formatted as follows TEMP temp values F HUMID zhumid value Yo FLDSTR fldstr value Yo The temperature value will be an integer between ambient and 250 degrees F The humidity value will be a floating point between 0 0 and 100 0 The field strength value will be a running average of the last twenty five values sampled and will be a floating point between 0 0 and 100 0 If any of the fields contain it represents an over range value MS Excel Spread Sheet Data Logging An Excel spread sheet application UWAVE XLS has been developed which in conjunction with WinWedge application Gerling Applied Engineering Inc Modesto CA Product User Manual Page 22 EPRI Commercial Microwave Fabric Dryer software will collect the serial data directly and log all of the samples in sequential order The spread sheet then continuously calculates and displays stat
13. unknown Ambient conditions should be maintained as close to mid range as possible to ensure reliable operation The CMFD may be installed and operated on any level surface Adequate clearance must be provided on the sides and front near the louvered ducts to allow sufficient intake of dryer air Electrical Connections e Line Power A 4 conductor Hubbell Twist lock type connector is provided at the back of the CMFD Connections are to two phases plus ground with no neutral connection A mating connector and power cord is also provided Pinouts are as follows X Phase A any of three phases Y Phase B either of remaining two phases Gerling Applied Engineering Inc Modesto CA Product User Manual Page 9 EPRI Commercial Microwave Fabric Dryer G Ground W No connection normally used for neutral e Line Current Monitoring An 11 pin MS style circular connector J1 located on the back of the CMFD provides three separate analog voltage signals that are proportional 10VDC 100A to the line current drawn by corresponding subsystems within the CMFD A mating connector is also provided Pinouts are as follows Pins A A and B Microwave power supply current Pins C and D Basket and blower drive motors current Pins D and E Duct heaters current output disabled Pins F and H Not used reserved for later use Pins K L and M No connection Gerling Applied Engineering Inc Modesto CA Prod
14. accumulate on this Gerling Applied Engineering Inc Modesto CA Product User Manual Page 18 EPRI Commercial Microwave Fabric Dryer screen then it will gradually reduce the flow of exhaust air to the sensors thus reducing their sensitivity To prevent continual accumulation of lint on the sensor screen the lint is burned off at the end of every drying cycle by applying an electrical current through the screen This current is high enough to cause the lint to smolder but not ignite into an open flame The burn off period occurs after the blower stops so that the flow of air does not prevent the burn off temperature from being reached The lint ash is then carried away by the exhaust air at the start of the next drying cycle Low Voltage Power Supplies Drive Motors A Several low voltage power supplies provide power to various control circuits These power supplies are on whenever line power is connected to the CMFD and the main circuit breaker is turned on Their functions are described as follows e 24 VDC Power Supply This power supply is the primary source of control power to the CMFD Several devices are powered by this supply directly while others are powered through additional circuitry Devices connected to the output of this power supply are protected by a 5 Amp fuse e Gas Sensor Power Supply This power supply is dedicated to only the gas sensors to provide 5 VDC for heater power and 10 VDC for signal po
15. e operation and prevent microwave leakage the equipment must be periodically inspected and maintained as required or recommended Gerling Applied Engineering Inc Modesto CA Product User Manual Page 4 EPRI Commercial Microwave Fabric Dryer TABLE OF CONTENTS INTRODUCTION biin ke BNG KAN AGANG aNG 5 GENERAL DESCRIPTON paaa NANANA ka no an pa kan e am an nnne 6 Electrical Specifications 7 Mechanical Specifications 7 Controls 7 Sensors 7 INSTALLATION 53G don de onon kk ki a n n e a e n po do do 8 Preliminary Inspection 8 Facilities Requirements 8 Location 8 Electrical Connections 8 BASIC OPERATION inik ok tit n tt n kt n tn n n a n n n n a e n ot A 10 Initial Power Up 10 Dryer Loads 10 Drying Cycle Setting 11 Cycle Start 11 Cycle Stop 12 Sensor Lint Screen Burn off 12 Fault Cycles 12 Lint Screen Cleaning 13 THEORY OF OPERATION aaa AABANG a kk kk 14 Dielectric Heating 14 Microwave Power Generators 14 Field Strength Sensor 15 Arc Detector 16 Exhaust Humidity Sensor 16 Exhaust Gas Sensors 17 Magnetron Thermal Cutouts 17 Sensor Lint Screen Burn off 17 Low Voltage Power Supplies 18 Drive Motors 18 USER MAINTENANCE Lana aaa 20 Lint Screen Cleaning 20 PROCESS DATA COLLECTION a r m n ka ik n bo n ko bo dap ANAN 21 Terminal Emulator Data Logging 21 MS Excel Spread Sheet Data Logging 21 ATTACHMENTS Document Type Number Title Drawing 910037 Outline Drawing Drawing 910038 Block Diagram Control System Drawing 910048
16. icrowave energy is absorbed primarily in the water rather than the fabric resulting in heating and vaporizing of the moisture The fabric tends to stay relatively cool because it is not being heating directly By contrast the hot air used in conventional dryers heats the fabric and the moisture simultaneously resulting in higher overall drying temperatures However as moisture is vaporized and leaves the microwave dryer the tendency to heat the fabric directly becomes greater If microwave energy remains on after the moisture has been removed then damage to the fabric from burning could result Microwave Power Generators The microwave power generators used in the CMFD consist of three main elements a magnetron oscillator a high voltage power supply and a filament power supply The magnetron is a vacuum tube oscillator that is designed operate at the desired frequency 2450 MHz Like other types of vacuum tubes it contains an anode a cathode and a filament heater and operates when the filament is hot and a sufficiently high voltage is present across the anode and cathode Gerling Applied Engineering Inc Modesto CA Product User Manual Page 15 EPRI Commercial Microwave Fabric Dryer The high voltage also referred to as the plate voltage is generated in the CMFD using a full wave voltage doubler power supply This power supply consists of two separate power supply sections operating on alternate phases of the li
17. inadequate air flow and faulty operation of the CMFD Gerling Applied Engineering Inc Modesto CA Product User Manual Page 14 EPRI Commercial Microwave Fabric Dryer THEORY OF OPERATION Dielectric Heating This section explains in detail the various functions features and control sequences of the CMFD Knowledge of these details will assist the operator and service personnel to understand how the functions interact interpret process results and diagnose operational difficulties Refer to the attached schematic drawings for further details in conjunction with the discussion below Microwave or dielectric heating occurs when electromagnetic fields oscillating at a specific frequency 2450 MHz interact with certain kinds of molecules having a high dipole moment These molecules try to align themselves with the electric fields as they rapidly reverse polarity at the oscillating frequency causing them to vibrate The resulting friction between adjacent molecules generates heat Materials containing highly polar molecules are said to be lossy because they readily absorb microwave energy A measure of this lossiness is a property of the material known as its dielectric loss or loss tangent Water is a good example of a lossy material because its molecules have a high dipole moment Most fabrics are made of materials having a relatively low dielectric loss far lower than that of water In the microwave fabric dryer m
18. istics for each of the three data values The Excel spread sheet can be opened from either Windows 95 or Windows NT However Windows NT is highly recommended due to the enhanced speed of the transmitted data After opening the spread sheet any residual values in the cells should be cleared using the CLEAR button in the upper left hand corner After the spread sheet is cleared the WinWedge software program must be initiated one time by clicking on the respective button This program will link the serial data received to the Excel spread sheet using the windows DDE communication The program can also be started using the shortcut keys CTRL SHIFT W but care must be taken to ensure that only one program is running at any given time After the WinWedge software has successfully started the ribbon cable from the CMFD can be connected to the remote computer s COM1 serial port to begin logging data The number of samples collected will be indicated in the upper left hand corner of the spread sheet After the dryer cycle the cable should be removed to stop collection and charts can be automatically generated using the special buttons provided The spread sheet should then be saved to a unique file name so that the template spreadsheet file UWAVE XLS can be used repeatedly After the spread sheet has been saved close and then reopen the UWAVE XLS spreadsheet in order to start from the top of the sheet NOTE The UWAVE XLS spreadsheet must reside in
19. ne cycle Each section also referred to as a half wave voltage doubler and known for its output voltage regulating characteristics is similar to power supplies used in conventional microwave ovens A diode network combines the outputs of these two sections to deliver a fixed voltage to the magnetron which in turn delivers fixed output microwave power to the dryer The filament power supplies consist simply of a high current isolation transformer and a network of variable resistors to control the voltage delivered to the transformer primary winding Because of backheating inside the magnetron the voltage required during operation is lower than during idle periods A relay whose contacts are used to change the amount of resistance in the primary line is energized whenever line voltage is applied to the plate voltage power supply To provide a short warm up period prior to application of plate voltage the filament power supplies are turned on approximately five seconds before the plate voltage supplies Field Strength Sensor The field strength sensor monitors the electric field strength inside the dryer cavity It operates by sensing the microwave field using a small wire probe and converting the signal to a DC voltage using a crystal diode The microprocessor monitors the field strength signal and controls the amount of microwave power as required to prevent damage The field strength varies with the level of microwave power delivered
20. o accommodate most typical fabrics used in clothing or other standard textile products However it should be noted that some fabrics may contain certain materials that will result in fault conditions during the drying process While the CMFD is designed to protect itself and the operator from such loads the operator should take necessary precautions to avoid loads containing the following materials e Metallic fabrics such as woven metal screens e Metallic or metalized threads e Heavily studded sequined or ornamented fabrics a few metal studs or metal zippers are generally OK Gerling Applied Engineering Inc Modesto CA Product User Manual Page 11 EPRI Commercial Microwave Fabric Dryer A e Non fabric objects such as pencils cigarette lighters coins hair pins etc The CMFD generally performs better and more reliably with full loads than with lighter loads Also loads should be evenly wetted as would be typical following a standard wash cycle with spin drying CAUTION Loads must not contain excessive amounts of moisture such that water is allowed to accumulate inside the dryer cavity and or drip down from the dryer basket Failure to prevent water accumulation and dripping may result in electrical damage to the CMFD Spin drying of all loads prior to microwave drying is highly recommended Drying Cycle Setting Cycle Start Any one of three drying cycles can be selected depending on the type of fabric load
21. rcise extreme caution when opening the cavity door and handling fabrics during the middle of a drying cycle Sensor Lint Screen Burn off Fault Cycles The final stage of the drying cycle following the end of cycle buzzer is a ten second period during which the sensor lint screen burn off occurs see related discussion in Theory of Operation section The operator is typically unaware that this burn off is occurring However if the cavity door is opened during this period then the general fault cycle will be initiated see below Any of the following fault cycles may be initiated during the drying cycle due to abnormal operating conditions Gerling Applied Engineering Inc Modesto CA Product User Manual Page 13 EPRI Commercial Microwave Fabric Dryer e General Fault Cycle This cycle occurs when any one of several interlock devices covers lint screen door cavity door thermal cutouts becomes dissatisfied or the microwave field strength exceeds specified limits During this cycle the Check Load lamp immediately lights up the basket and blower both stop and the buzzer sounds for ten seconds The load must be checked prior to restarting e Gas Sensor Fault Cycle This cycle is similar to the general fault cycle except that it begins with a thirty second period during which the microwave power supplies and heaters are turned off as evidenced by the clack of the contactors turning off but the basket and blower con
22. thers are required in order to address inherent deficiencies in the original design These changes are identified and discussed in detail within this Manual where applicable and reliable operation of the CMFD Gerling Applied Engineering Inc hereby disclaims all responsibility or liability for poor reliability unsatisfactory performance unsafe operation or any other problem associated with the design and construction of the CMFD Operators and end users assume all risks associated with operation of the CMFD Do NOTE While GAE has made extensive efforts to ensure safe WARNING Lethal voltages may exist inside the CMFD during A operation and non operation All maintenance and service must be done by qualified technical personnel only Under no circumstances should untrained or unskilled personnel be allowed access inside the CMFD Gerling Applied Engineering Inc Modesto CA Product User Manual Page 6 EPRI Commercial Microwave Fabric Dryer GENERAL DESCRIPTION The EPRI Commercial Microwave Fabric Dryer CMFD is designed for field trials of the microwave fabric drying process in commercial establishments to dry fabric loads up to 12 pounas lt combines microwave energy with conventional hot air to dry almost any type of fabric load at faster rates and lower temperatures than conventional dryers using hot air alone A microprocessor control System coordinates operation of the dryer by collecting data from a variety
23. tinue to operate This first stage is immediately followed by a stage identical to the general fault cycle described above Aside from the clack of the contactors the operator may be completely unaware that this fault cycle has been initiated until the second stage begins Checking the load will usual provide clues to help differentiate between gas sensor and general faults e Arc Detect Fault Cycle The presence of metallic fabric or objects can when combined with light loads and high field strengths cause arcing to occur inside the dryer cavity Arcs are detected by a photo diode which sends a voltage signal to sensitive electronic circuitry that initiates the fault cycle During an arc detect fault cycle the Arc Detect lamp is turned on and the drying cycle is immediately stopped The Stop button must be pressed to clear the fault condition and reset the dryer for normal operation NOTE Due to unresolved difficulties associated with nuisance tripping of the arc detect circuit this feature has been temporarily disabled However other protection devices remain in place such as the gas sensors which will adequately protect the dryer and operators from harm in the event of conditions that could cause arcing in the dryer cavity Lint Screen Cleaning The lint screen located inside the panel beneath the cavity door should be inspected regularly and cleaned as necessary Failure to properly clean the lint screen may result in
24. to the cavity and the amount of moisture and fabric inside the cavity If the field strength is too high then damage could result to the fabrics and or dryer At the beginning of the drying process moisture content is generally high thus the field strength is relatively low As the drying process progresses and moisture is removed from the dryer cavity the field strength gradually climbs If the field strength signal reaches or exceeds a setpoint value roughly equal to 80 of the maximum allowable field the microprocessor shuts off one of the magnetrons by de energizing a relay thus lowering the field strength to within acceptable limits and allow the drying process to continue As drying progresses and the moisture content continues to drop field strength will again reach a the setpoint value At this point the microprocessor will turn off a second magnetron to further reduce the field strength The drying process will then continue with only one magnetron operating until the field strength setpoint is reached Gerling Applied Engineering Inc Modesto CA Product User Manual Page 16 EPRI Commercial Microwave Fabric Dryer Arc Detector CO This time the microprocessor will turn off all magnetrons and initiate the End of Cycle routine By this discussion it can be understood that full loads are preferred to light loads so as to maintain the electric field strength at relatively low levels throughout the drying process
25. tor arc detector exhaust gas sensors Gerling Applied Engineering Inc Modesto CA Product User Manual Page 8 EPRI Commercial Microwave Fabric Dryer INSTALLATION Preliminary Inspection Upon arrival at the installation site the CMFD should be thoroughly inspected for damage or wear caused during shipping Any visible damage to the shipping crate or CMFD should be noted and reported immediately to the shipping company in accordance with standard claims procedures Prior to connecting line power the outer covers should be removed and all electrical connections inspected for loose or disconnected wires All mechanical components should also be inspected for any loose or broken hardware or other wear that may have been caused during shipping Facilities Requirements Location e Line Power 208 220 VAC 60 Hz single phase 60 Amps 2 wire plus ground Proper earth ground must be provided Please note that while an internal line filter is provided the CMFD has not been tested for immunity to noise spikes or other line power conditions that may be present in typical industrial environments A line conditioner and or regulator may be required for satisfactory operation of the CMFD e Exhaust Duct Standard 4 diameter dryer exhaust duct Back pressure must be minimized e Environment Indoors only must be clean and dry The allowable extremes of ambient temperature and humidity have not been tested and are thus
26. ty in any event for incidental or consequential damages financial losses penalties or other losses incurred in conjunction with the use of GAE products DOCUMENT CONVENTIONS NOTE Means the reader should take note Notes contain helpful information suggestions or references to other sections chapters or documents CAUTION Means the reader should be careful You are doing something that might result in equipment damage or loss of data WARNING Means danger A situation exists that could cause bodily injury or death All personnel must be aware of the hazards involved with high voltage electrical circuitry and high power microwave devices bb 2 Gerling Applied Engineering Inc Modesto CA Product User Manual Page 3 EPRI Commercial Microwave Fabric Dryer WARNING The microwave dryer described in this manual is capable of producing a microwave field that is potentially hazardous to operating personnel The unit must never be connected or operated in a manner that allows a field in excess of 10 milliwatts per square centimeter to be generated in an area accessible to operating personnel Contact GAE Inc for technical support prior to installation and or operation of these units if there is any question or concern about microwave leakage All electrical cable connections must be secure prior to operation Never operate the microwave dryer without a properly rated absorbing load inside the oven cavity To ensure saf
27. uct User Manual Page 10 EPRI Commercial Microwave Fabric Dryer BASIC OPERATION Initial Power Up m Dryer Loads Operation of the CMFD is very similar to that of a conventional residential clothes dryer A typical sequence of events is as follows e Load fabrics to be dried and close door e Select drying cycle e Press Start button to begin drying e Wait for buzzer signaling end of drying cycle e Open door and remove dried fabrics While this operation sequence appears to be relatively simple there are many subtle aspects of the CMFD s operation as explained below that should be fully understood by the operator After connecting line power as described in the Installation section of this manual power is applied to the CMFD by lifting the circuit breaker handle located near the line power connector on the back panel This applies power to various low voltage power supplies which in turn supply power to the microprocessor and other controls NOTE One of the subsystems to which initial power is applied is the suite of four separate gas sensors These sensors require a warm up period of approximately one hour for stable performance Line power can remain on indefinitely so there is no need to turn off and disconnect line power between daily periods of operation However as a safety precaution it is recommended that line power be disconnected during extended periods of non operation The CMFD is designed t
28. wer This dedication is necessary to maintain stability of the supply voltages to help prevent erratic performance of the sensors e Voltage Regulators Two voltage regulators provide 15 VDC to the humidity sensor and 5 VDC to the microprocessor and various other devices and circuitry Two different electric motors are used to drive the blower and dryer basket Both motors operate simultaneously during all periods of dryer operation except when the buzzer is on fault or end of cycle and during the sensor lint screen burn off The blower is driven by a fixed speed AC motor while the basket is driven by a variable speed DC motor The speed of the basket motor and thus the basket rotation speed can be varied by adjusting a trimming potentiometer R10 located near the bottom edge of the microprocessor interface PC board CAUTION Excessive basket rotation speed can cause damage to the internal basket support rollers and drive mechanism The basket speed should be such that the fabrics are allowed to fall Gerling Applied Engineering Inc Modesto CA Product User Manual Page 19 EPRI Commercial Microwave Fabric Dryer freely through the center of the cavity as they tumble In any case the maximum allowable basket rotation speed is 60 rpm Gerling Applied Engineering Inc Modesto CA Product User Manual Page 20 EPRI Commercial Microwave Fabric Dryer USER MAINTENANCE The CMFD is designed to relatively maintenance
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