OPERATION & SERVICE MANUAL - Absolute Process Instruments
Contents
1. they are zero or vary by more than a few millivolts from the expected voltage troubleshoot as follows in steps 3 3 1 through 3 3 4 3 3 1 Confirm that switch SW2 is completely switched to the EXT position and that the individual switches in SW1 are in the up or ON position Move the switches to their opposite position and back again to confirm that they have completely seated in the correct position 3 3 2 Make sure all Excitation Adjust potentiometers LC1 LC2 LC3 LC4 mounted above SW1 are set at maximum by turning fully clockwise The potentiometers are 25 turn and a slight clicking sound can be heard and or felt at the endpoint Recheck excitation voltage readings 3 3 3 If the problem continues remove the wiring to terminals 1 EXC and terminals 2 EXC of each load cell terminal block LC1 LC2 LC3 and LC4 Recheck excitation voltage readings 3 3 4 If the problem goes away connect each strain gauge one at a time to its corresponding terminal block and measure the value at terminals 1 and 2 Repeat as necessary for the remaining strain gauges If the problem re occurs check for improper strain gauge wiring and or a faulty load cell 4 Ifthe voltage readings vary by a few millivolts adjust each Excitation Adjust potentiometer LC1 LC2 LC3 LC4 mounted above SW1 so that the readings at terminals 1 and 2 of the corresponding terminal blocks are exactly equal to the excitation voltage required Page 5 of 12 Absolute Proc2. Absolute Process Instruments Inc 800 942 0315 www api usa com API SUM 000 Strain Gauge Summing Board API SUM 025 Strain Gauge Summing Board with API 4059 G Signal Conditioning Module Installation Calibration Operation API SUM 000 API SUM 02 Table of Contents Page Functional Description 2 ananamanaaasa 2 Specifications AGANG 2 Board Installation maa ANA nA 2 WINNING nana AANGAT GANG 3 API SUM 000 SAUpu aaa Aa 4 API SUM 000 Excitation Voltage Calibration 1 1 7 2 5 API SUM 000 Load Cell Calibration mmmnnmananananamanananaunaanana 6 API SUM 025 Setup vicecsictccccccececscccescececcessnccassncs ceessscsncccoseanersonenseesees 7 API SUM 025 Callibration ccccsecsseesessseesseeeeeeeeeeeeeseeessneeeseeenes 8 API SUM 025 Excitation Voltage Calibration cccssessseeseee 9 API SUM 025 Load Cell Calibration ccccssecssesseeseeeeseeeeseees 10 API SUM 025 Final Adjustment c csscssseeesseesseeeeeeeeeeseeessees 10 API SUM 025Troubleshooting ccesecesecesseeeeeeeeeseeseeeeeeseeeeeeees 11 Strain Gauge Load Cell Information s ccsseeseeseeeseeeeeens 12 Rev 09 05 SUMXXXMAN API SUM Strain Gauge Summing Board FUNCTIONAL DESCRIPTION The API SUM 000 Strain Gauge Summing Assembly consists of a sum board and an optional field rangeable strain gauge signal conditioning module that plugs into the 11 pin socket on the board Th
3. ON Connect the external excitation supply wiring to terminal block J5 terminals 1 EXT EXC and 2 EXT EXC Observe wiring polarity The summed mV output from the strain gauges is present at terminal block J5 terminal 6 OUT and J5 terminal 7 OUT Use these terminals to connect your external device to read the summed strain gauge output Ensure all connections are correctly wired and securely tightened Proceed to API SUM 000 SETUP API SUM 025 WIRING ALL POWER MUST BE DISCONNECTED OR TURNED OFF DURING INSTALLATION The summed strain gauge mV signal is converted to a DC voltage or current output by the signal conditioner This output signal is present at terminal block J5 terminals 4 and 5 Connect your compatible external device to read the signal output See label on signal conditioner for correct operating power Connect the appropriate power to terminal block J6 Make sure all connections are correctly wired and securely tightened Proceed to API SUM 025 SETUP O External Excitation External Load Cell Terminal 1 Excitation BI Signal Signal BS Load Cell Terminal 2 Excitation BM Excitation KIKI Shield BQ Signal BQ Signal HO Load Cell Terminal 3 Excitation BQ Excitation AKI Shield BI Signal II Signal BS Load Cell Terminal 4 Excitation BQ Excitation KIKI Shield EI Signal gt II Signal BO T LC 1 Excitation UP J5 Signa
4. and SIG of each terminal block LC1 LC2 LC3 and LC4 Take care to place the weight directly over the cell if possible or in the same position relative to the cell each time a reading is taken This will minimize the number of times the procedure must be repeated Terminal Block LC1 SIG to SIG Signal Voltage Volts Terminal Block LC2 SIG to SIG Signal Voltage Volts Terminal Block LC3 SIG to SIG Signal Voltage Volts Terminal Block LC4 SIG to SIG Signal Voltage Volts If the voltage readings are equal sum board calibration is complete Any further calibration is done at API SUM 025 FINAL ADJUSTMENT If there is any variation continue with step 3 Disable the load cells by sliding the individual switches on SW1 to the OFF down position except for the load cell that had the highest recorded reading in step 1 It is not necessary to disconnect the load cell wiring Do not enable any of the other load cells at this time Apply the same test weight from step 1 in the same position over the high reading load cell Connect the voltmeter leads to terminal block J5 to read terminals 4 SIG and 5 SIG While monitoring the reading at J5 SIG and J5 SIG turn the Signal Adjust potentiometer LC1 LC2 LC3 or LC4 below SW1 corresponding to the enabled cell so that the meter reads the same as the lowest value recorded in step 1 Repeat steps 3 through 6 for each strain gauge load cell that read greater
5. arately from the API SUM board or while installed on the board If the module has been pre calibrated for the application skip to API SUM 025 EXCITATION VOLTAGE CALIBRATION There are two methods for calibrating the strain gauge signal conditioning module while it is plugged into the API SUM board The method you choose will depend upon the test equipment available Millivolt Generator Method 1 2 10 11 The strain gauge signal conditioning module must be plugged into the 11 pin socket The power connected to terminal block J6 must match the power required by the strain gauge signal conditioning module or damage will occur When correct apply power The Green and Red Loop Tracker LEDs on the module should illuminate If one or both lights do not illuminate go to the Troubleshooting section Disable all strain gauges load cells by sliding all four switches of SW1 to the OFF down position It is not necessary to disconnect the load cell wiring Set slide switch SW2 to the EXT up position Connect an accurate millivolt generator to terminal block J5 terminals SIG and SIG Connect an accurate voltmeter to terminal block J5 terminals SIG and SIG Follow the setup and calibration procedures on the data sheet supplied with the module Use the millivolt generator as the input and read the output with the digital voltmeter Disconnect the millivolt generator and digital voltmeter Reposition SW2 to the INT down pos
6. d on the load cells Repeat steps 3 through 6 as required for final tuning Reconnect the output wiring to J5 terminals 6 OUT and 7 OUT Remove all test leads Calibration is complete Page 10 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 025 TROUBLESHOOTING 1 Both API 4059 LoopTracker LEDs are not illuminated 1 1 Confirm that the power wiring to terminal block J6 terminals 1 2 and 3 is correct and that all connections are secure 1 2 Check to ensure the strain gauge signal conditioning module is inserted fully into its socket 1 3 Using a digital voltmeter measure the power at J6 terminals 1 AC or DC and 3 AC or DC to confirm incoming power The power MUST match that of the strain gauge signal conditioning module Only one API 4059 LoopTracker LED is illuminated 2 1 Check to make sure the strain gauge signal conditioning module is inserted fully into its socket 2 2 If the Green LED S NOT illuminated check all input wiring from the load cells to the terminal blocks LC1 LC2 LC3 and LC4 for incorrect connections or broken wires Confirm strain gauge or load cell manufacturer s wiring 2 3 If the Red LED IS NOT illuminated check all output wiring from the API SUM board terminal block J5 to the destination for incorrect connections or broken wires 2 4 Remove the strain gauge signal conditioning module from its socket and reconfirm that a
7. e board will accept up to four 350 Q or greater strain gauges load cells and provide an output proportional to the sum of the active strain gauges The API SUM board can be mounting in commonly available NEMA enclosures If a strain gauge signal conditioning module is not used the API SUM 000 functions as summing board for the active strain gauges load cells A stable external excitation supply must be connected to the board The resulting output will be an unconditioned mVDC signal equal to the sum of the active strain gauges load cells The API SUM 025 Strain Gauge Summing Assembly consists of the sum board and the API 4059 field rangeable strain gauge signal conditioning module that plugs into the 11 pin socket on the board The strain gauge signal conditioning module provides a stable source of excitation field rangeable from 1 to 10 VDC sufficient to power up to four 350 Q strain gauges load cells The signal conditioner can also be field ranged for various input sensitivities The signal conditioner can also be field ranged for DC voltage outputs up to 10 VDC or DC current outputs up to 20 mADC An offset adjustment on the signal conditioner allows the user to cancel or tare non zero deadweights in the application Refer to the data sheet for the API 4059 Exclusive features of API strain gauge signal conditioning module include two LoopTracker LEDs and the Functional Test Pushbutton The LoopTracker LEDs green for input red fo
8. ess Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 000 LOAD CELL CALIBRATION 1 Apply the same known test weight sequentially and individually over each load cell Measure and record the readings at terminals 4 and 5 SIG and SIG of each terminal block LC1 LC2 LC3 and LC4 Take care to place the weight directly over the cell if possible or in the same position relative to the cell each time a reading is taken This will minimize the number of times the procedure must be repeated Terminal Block LC1 SIG to SIG Signal Voltage Volts Terminal Block LC2 SIG to SIG Signal Voltage Volts Terminal Block LC3 SIG to SIG Signal Voltage Volts Terminal Block LC4 SIG to SIG Signal Voltage Volts Each voltage reading should be very close or equal to each other If the voltage readings are equal sum board calibration is complete and any further calibration or scaling is done at the user s display or control equipment If there is any variation continue with step 3 Disable the load cells by sliding the individual switches on SW1 to the OFF down position except for the load cell that had the highest recorded reading in step 1 It is not necessary to disconnect the load cell wiring Do not enable any of the other load cells at this time Apply the same test weight from step 1 in the same position over the high reading load cell Connect the volt meter leads to
9. in gauge signal conditioning module from its socket 4 4 Using the range selection tables supplied with the module confirm that all switches are set properly for the desired excitation voltage input and output 4 5 THE POWER INPUT and OUTPUT SETTINGS FOR ALL TEST EQUIPMENT MUST MATCH THE CONFIGURATION OF THE STRAIN GAUGE SIGNAL CONDITIONING MODULE OTHERWISE PERMANENT DAMAGE MAY OCCUR 4 6 Using the proper test and calibration equipment check all functions on the strain gauge signal conditioning module for correct operation Refer to the data sheet provided 4 7 If a problem exists call the factory at 800 942 0315 for assistance 4 8 If the set up and operation of the module is correct return to the section where the original problem occurred and repeat all tests Page 11 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board STRAIN GAUGE LOAD CELL INFORMATION Troubleshooting a Pressure Transducer Load Cell Strain Gauge or Bridge Using a meter with at least 10 megaohm input impedance measure the voltage coming from the strain gauge at the locations shown Sensitivity is measured in mV V Positive Negative Meter Reading Meter Reading Meter Lead Meter Lead No pressure load Full pressure load tc Be Excitation Excitation Voltage Excitation Excitation Voltage JJ E E Excitation Voltage C a Excitation Voltage 72 x Excitation Voltage x Sens
10. ition Re enable all active load cells by sliding their corresponding switches on SW1 to the ON up position Skip to API SUM 025 EXCITATION VOLTAGE CALIBRATION Bridge Simulator Method 1 2 10 The strain gauge signal conditioning module must be plugged into the 11 pin socket The power connected to terminal block J6 must match the power required by the strain gauge signal conditioning module or damage will occur When correct apply power The Green and Red Loop Tracker LEDs on the module should illuminate If one or both lights do not illuminate go to the Troubleshooting section Disconnect the load cell wiring from terminal block LC1 It is not necessary to disconnect the wiring at LC2 LC3 or LC4 Turn on LC1 by sliding switch 1 of SW1 to the ON up position Turn off LC2 LC3 and LC4 by sliding switches 2 thru 4 of SW1 to the OFF down positions Connect an accurate Bridge Simulator to terminal block LC1 in place of the actual load cell Slide switch SW2 must be in the INT down position Connect an accurate digital voltmeter to terminal block J5 terminals SIG and SIG Follow the setup and calibration procedures on the data sheet supplied with the module Use the bridge simulator as the input and read the output with the digital voltmeter Disconnect both the bridge simulator and digital voltmeter Reconnect the strain gauge load cell to terminal block LC1 Turn on all active load cells by sliding their co
11. itivity Excitation Voltage Excitation Voltage 72 x Excitation Voltage x Sensitivity Zero Volts Excitation Voltage x Sensitivity Typical wiring color codes for load cells Always consult manufacturer Exceptions and or custom wire colors exist Manufacturer Excitation Excitation Signal i Shield Sense Sense A amp D Allegany Artech Beowulf BLH Cardinal Celtron Digi Matex Dillon Electroscale Green Entran Yellow or Green Evergreen White Flintec i Yellow Force Measurement i Bare Futek General Sensor GSE HBM HBM PLC SBE i Yellow Interface i Bare Kubota i Yellow LeBow i Bare Mettler Toledo i Orange Yellow National Scale i Yellow NCI Red Black White Green Bare Yellow Blue Nikkei Red Black Green White Bare Pennsylvania Orange Blue Green White Blare Philips Bare Presage Promotion i Yellow Revere i Orange Rice Lake Sensortronic Sensortronic column Sensotec Strainsert T Hydronics Tedea Huntleigh i Blare Brown Thames Side Bare Toledo i Yellow Totalcomp i Blare Transducers Inc i Orange Weigh Tronix i Orange Page 12 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502
12. l Output KIKI External Exc DA External Exc DE Shield Internal KEY Signal Excitation DA Signal DOWN KI Out Ak Out Excitation Adjust LC1 LC2 LC3 LC4 Turn pots clockwise to J6 Power KIEHAC or DC KIKI Ground QIEIAC or DC LC1 LC2 LC3 LC4 Signal Adjust 11 Pin Socket for API 4058 G or API 4059 G O 0 25 dia 7 locations Page 3 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 000 SETUP 1 2 Set slide switch SW2 to the EXT position up The external excitation supply and mVDC output wiring should be connected to terminal block J5 For each strain gauge load cell installed the corresponding slide switch SW1 is set to the ON up position The load cell terminal blocks and slide switches are matched as follows Terminal Block LC1 SW1 1 Terminal Block LC2 SW1 2 Terminal Block LC3 SW1 3 Terminal Block LC4 SW1 4 If a strain gauge load cell is not being used slide its corresponding switch to the OFF down position The individual switches in SW1 are used to electrically add or remove the corresponding load cell This is useful when less than four load cells are used or if one or more must be removed for service Before calibration set all Signal Adjust potentiometers LC1 LC2 LC3 LC4 mounted below SW1 to maximum by turning fully clockwise CW The potentiometers are 25 turn a
13. ll the switches are set properly If possible check the calibration separate from the API SUM board After confirming the calibration and correct operation of the module re insert it into its socket on the API SUM board and re apply power If the problem still exists call the factory at 800 942 0315 for assistance The DC voltage or current output is zero or does not match the calibration of the API 4059 3 1 Check the Red and Green LEDs on top of the module They should both be illuminated If one or both LEDs are NOT illuminated see above 3 2 Push the Test Pushbutton on top of the module The Green and Red LEDs on top of the module should both illuminate to approximately mid intensity 3 3 Connect a digital voltmeter to terminal block J5 terminals 6 OUT and 7 OUT Again push and hold the Test Pushbutton on top of the module The output should be equal to the value that was preset during calibration of the module 3 4 Check to make sure the strain gauge signal conditioning module is inserted fully into its socket and test again 3 5 Go to the next section to test the strain gauge signal conditioning module Testing the strain gauge signal conditioning module 4 1 If it is NOT possible or desirable to test the strain gauge signal conditioning module separate from the API SUM board call the factory at 800 942 0315 for assistance 4 2 REMOVE ALL POWER TO THE API SUM BOARD ASSEMBLY 4 3 Carefully remove the stra
14. nd a slight clicking sound can be heard and or felt at the endpoint The potentiometer will not be damaged by turning beyond the endpoint Before calibration set all Excitation Adjust potentiometers LC1 LC2 LC3 LC4 mounted above SW1 to maximum by turning fully clockwise CW The potentiometers are 25 turn and a slight clicking sound can be heard and or felt at the endpoint The potentiometer will not be damaged by turning beyond the endpoint Page 4 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 000 EXCITATION VOLTAGE CALIBRATION 1 Measure and record the Excitation Voltage at terminal block J5 terminal 1 EXC and terminal 2 EXC Terminal Block J5 EXC to EXC Excitation Voltage Volts 2 Measure and record the Excitation Voltage at terminal 1 EXC and terminal 2 EXC of each load cell terminal block LC1 LC2 LC3 and LC4 that is being used Terminal Block LC1 EXC to EXC Excitation Voltage Volts Terminal Block LC2 EXC to EXC Excitation Voltage Volts Terminal Block LC3 EXC to EXC Excitation Voltage Volts Terminal Block LC4 EXC to EXC Excitation Voltage Volts 3 Each voltage reading should be very close or equal to the excitation voltage supplied externally 3 1 If the voltage readings are equal skip to API SUM 000 LOAD CELL CALIBRATION 3 2 If they vary by only a few millivolts skip to step 4 3 3 If
15. r output act as power on indicators and track the signal strength by varying in intensity as the process variable changes The LoopTracker greatly aids in setup and troubleshooting of your system The Functional Test Pushbutton when depressed will generate an output independent of the input signal This output is preset at the factory at 50 of the calibrated output but can be scaled in the field from 0 to 100 of the selected output via a top accessible multi turn potentiometer SPECIFICATIONS Dimensions Board only 6 85 Wide X 8 75 High X 0 75 Deep Board material thickness 0 094 With API 4059 G 6 85 Wide X 8 75 High X 3 75 Deep Strain Gauge Inputs Up to four 350 Ohm or greater strain gauges load cells API SUM 025 Signal Conditioning Module Specifications Power 115 VAC standard 2 5 Watts maximum Optional power 230 VAC with API 4059 G A230 Optional power 9 30 VDC using API 4059 G D API SUM 025 Strain Gauge Excitation Supply Field rangeable from 1 to 10 VDC Strain Gauge Sensitivity Signal Field rangeable sensitivities Refer to corresponding module data sheet for details API SUM 025 DC Voltage or Current Outputs Field rangeable DC voltages from 10 VDC to 10 VDC Field rangeable DC currents up to 20 mADC at 20 VDC compliance BOARD INSTALLATION Ensure proper operation and protection by securely mounting for the AP SUM board and strain gauge signal conditioning module if used in an enclosure designed fo
16. r the environment in which it will be used Appropriate wire glands must be used to route wiring into housing API will not be responsible for damage that occurs or any code violations due to improper enclosure selection or installation Seven mounting holes are provided one at each corner for securing the board and three surrounding the eleven pin socket for added support at the socket The board must be spaced a minimum of 4 inch from the mounting surface using commonly available insulated spacers The board must be secured at all four corners If the signal conditioning module is used insulated spacers and fasteners MUST be used for the three mounting holes around the socket as well Page 2 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board WIRING PRECAUTIONS WARNING TURN OFF ALL POWER BEFORE WIRING To avoid interference all power wiring must be kept separate from the strain gauge and DC output wiring Wiring for each strain gauge load cell must be kept separate from other strain gauge power or output wiring Each strain gauge load cell should be routed separately and directly to its corresponding terminal block Connect the strain gauges load cells to the appropriate terminal blocks LC1 LC2 LC3 and LC4 Refer to the load cell manufacturer s wiring diagram for correct wiring API SUM 000 WIRING DISCONNECT POWER TO THE EXCITATION SUPPLY DURING INSTALLATI
17. rm that they have completely seated in the correct position 3 3 2 Make sure all Excitation Adjust potentiometers LC1 LC2 LC3 LC4 mounted above SW1 are set at maximum by turning fully clockwise The potentiometers are 25 turn and a slight clicking sound can be heard and or felt at the endpoint The potentiometer will not be damaged by turning beyond the endpoint Recheck excitation voltage readings 3 3 3 If the problem continues remove the wiring to terminals 1 EXC and terminals 2 EXC of each load cell terminal block LC1 LC2 LC3 and LC4 Recheck excitation voltage readings 3 3 4 If the problem goes away connect each strain gauge one at a time to its corresponding terminal block and measure the value at terminals 1 and 2 Repeat as necessary for the remaining strain gauges If the problem re occurs check for improper strain gauge wiring and or a faulty load cell 4 Ifthe voltage readings vary by a few millivolts adjust each Excitation Adjust potentiometer LC1 LC2 LC3 LC4 mounted above SW1 so that the readings at terminals 1 and 2 of the corresponding terminal blocks are exactly equal to the excitation voltage required Page 9 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 025 LOAD CELL CALIBRATION 1 Apply the same known test weight sequentially and individually over each load cell and record the readings at terminals 4 and 5 SIG
18. rresponding switches on SW1 to the ON up position Continue to API SUM 025 EXCITATION VOLTAGE CALIBRATION Page 8 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 025 EXCITATION VOLTAGE CALIBRATION 1 Measure and record the Excitation Voltage at terminal block J5 terminal 1 EXC and terminal 2 EXC Terminal Block J5 EXC to EXC Excitation Voltage Volts 2 Measure and record the Excitation Voltage at terminal 1 EXC and terminal 2 EXC of each load cell terminal block LC1 LC2 LC3 and LC4 that is being used Terminal Block LC1 EXC to EXC Excitation Voltage Volts Terminal Block LC2 EXC to EXC Excitation Voltage Volts Terminal Block LC3 EXC to EXC Excitation Voltage Volts Terminal Block LC4 EXC to EXC Excitation Voltage Volts 3 Each voltage reading should be very close or equal to the excitation voltage supplied externally 3 1 If the voltage readings are equal skip to API SUM 025 LOAD CELL CALIBRATION 3 2 If the vary by a few millivolts skip to step 4 3 3 If they are zero or vary by more than a few millivolts from the expected voltage troubleshoot as follows in steps 3 3 1 through 3 3 4 3 3 1 Confirm that switch SW2 is completely switched to the EXT position and that the individual switches in SW1 are in the up or ON position Move the switches to their opposite position and back again to confi
19. terminal block J5 to read terminals 4 SIG and 5 SIG While monitoring the reading at J5 SIG and J5 SIG turn the Signal Adjust potentiometer LC1 LC2 LC3 or LC4 below SW1 corresponding to the enabled cell so that the meter reads the same as the lowest value recorded in step 1 Repeat steps 3 through 6 for each strain gauge load cell that read greater than the lowest reading recorded in step 1 It is not necessary to adjust the signal potentiometer for the strain gauge load cell that had the lowest reading Once all necessary adjustments have been made repeat steps 1 through 7 until the readings are equal Once all readings are equal the sum board calibration is complete and any further calibration or scaling is done at the user s display or control equipment Page 6 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 025 SETUP The strain gauge signal conditioning module must be set up and calibrated to match the system requirements strain gauge sensitivities excitation supply voltages offset and output 1 Make sure the necessary steps on page 3 of this manual have been followed with regard to wiring and correct supply voltage to the module Plug the strain gauge signal conditioning module into the eleven pin socket Set slide switch SW2 to the INT position down In this position the API signal conditioner module will supply excitation
20. than the lowest reading recorded in step 1 It is not necessary to adjust the signal potentiometer for the strain gauge load cell that had the lowest reading Once all necessary adjustments have been made repeat steps 1 through 7 until the readings are equal Once all readings are equal the sum board calibration is complete and any further calibration done in the next section API SUM 025 FINAL ADJUSTMENT 1 2 The final step is to fine tune the zero and span potentiometers on the signal conditioning module for the correct DC output Temporarily disconnect the output wiring from terminal block J5 terminals 6 OUT and 7 OUT Make sure that there is no load on any of the load cells Using the digital voltmeter measure the output at terminal block J5 terminals 6 OUT and 7 OUT The reading should match the lowest value that was selected when calibrating the strain gauge signal conditioning module For example if 4 to 20 mADC is the desired output this reading should be 4 mADC Fine tune by adjusting the Zero pot on the module to obtain the desired output with no load Apply a full load to the load cells and measure the output at J5 terminals 6 OUT and 7 OUT The reading should now match the highest value chosen when calibrating strain gauge signal conditioning module For example if 4 to 20 mADC was chosen this reading should be 20 mADC Fine tune by adjusting the span pot on the module to obtain the desired output with a full loa
21. voltage to the load cells For each strain gauge load cell installed the corresponding slide switch SW1 is set to the ON up position The load cell terminal blocks and slide switches are matched as follows Terminal Block LC1 SW1 1 Terminal Block LC2 SW1 2 Terminal Block LC3 SW1 3 Terminal Block LC4 SW1 4 If a load cell is not being used slide its corresponding switch to the OFF down position The individual switches in SW1 are used to electrically add or remove the corresponding load cell This is useful when less than four load cells are used or when one or more must be removed for service Before calibration set all Signal Adjust potentiometers LC1 LC2 LC3 LC4 mounted below SW1 to maximum by turning fully clockwise CW The potentiometers are 25 turn and a slight clicking sound can be heard and or felt at the endpoint The potentiometer will not be damaged by turning beyond the endpoint Before calibration set all Excitation Adjust potentiometers LC1 LC2 LC3 LC4 mounted above SW1 to maximum by turning fully clockwise CW The potentiometers are 25 turn and a slight clicking sound can be heard and or felt at the endpoint The potentiometer will not be damaged by turning beyond the endpoint Page 7 of 12 Absolute Process Instruments Inc Phone 800 942 0315 Fax 800 949 7502 API SUM Strain Gauge Summing Board API SUM 025 CALIBRATION The strain gauge signal conditioning module can be calibrated sep
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