UPS 120, UPS 150, UPS 250, UPS 300, UPS 301, UPS 500, UPS 600, UPS 750 and UPS 900 Uninterruptible Power Supplies Caterpillar

Calibration of Current for the Field Coil

The field coils are used to generate magnetic fields in the flywheel.

The calibration procedure must be done whenever the following boards are replaced:

• APC board

• Field Coil Driver Board (FCD)

• Flywheel Interface Board (FWI) (Hall Effect Probe systems only)

Note: The flywheel must be in shutdown mode. The power from the bus can dissipate while you perform the calibration.

Note: Ensure that the RPM of the flywheel is zero.

1. Place the UPS into MAINTENANCE BYPASS.

   For SMS, refer to Systems Operation, Testing and Adjusting, RENR9988, "SMS Internal and Maintenance Bypass".

   For MMS, refer to Systems Operation, Testing and Adjusting, RENR9988, "MMS Internal and Maintenance Bypass".

2. Clamp the DC current probe around the conductor for the positive terminal for the top field coil in order to take a reading. Leave the DC current probe that is hanging on this conductor for the next reading. This reading should be zero.
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   NOTICE
   Probe must be clamped onto field coil lead correctly oriented to current direction. There is an arrow with reference symbols on the probe clamp. Orient the arrow point in the current direction.

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   Illustration 1	g01272888
   3000 A current probe clamp used for field coil calibration (1) Probe

3. Set meter to measure DC millivolts.

4. Attach a probe to the top field coil.

5. In order to adjust the probes, zero the multimeter.
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   Illustration 2	g01272890
   Adjustment of the probe for the field coil (2) Probe settings (3) Zero adjust

6. Adjust up to 10 mv per ampere (mV/A).

7. Ensure that the key switch for the flywheel is turned to the BYPASS position.

8. Connect a computer to the UPS. Refer to Systems Operation, Testing and Adjusting, RENR9988, "PC to UPS Connection".

9. In UPSView, click the "Calibrate" drop-down menu.

10. Select "Field Coil Currents" from the calibration menu. You will hear the input contactor close. The static switch will turn on. The DC bus will rise. A "Calibration of a Channel" window will open.

11. Select "View Status".

12. Select "Use Defaults".

13. Enter the minimum current value for the field coil that is shown on the multimeter.

14. Select "OK".

    The system switches to the maximum and the current value begins to rise.

15. Allow current to stabilize.

16. Enter maximum field coil current.

17. Select "OK".

18. Switch the probe to the bottom of the field coil (BFC+) on the flywheel field coil driver board.

19. Enter the value that is shown on the multimeter.

20. Select "OK".

    The current value begins to rise. The "Calibration of a Channel" window will switch to maximum.

21. Enter the value that is shown on the multimeter.

22. Select "OK".

23. Select "Save".

    Note: "Maximum" button on "Calibration of a Channel" window will be automatically selected and the current will ramp to approximately 15 amps.

24. Take another reading for the top field coil.

25. Enter the value from the previous step in the "Enter Calibration Point" field.

26. Click "OK". The system will process calibration. The system will prompt "Enter Calibration Point" for "Bottom Field Coil Current" automatically.

27. Clamp the DC current probe around the conductor of the positive terminal for the bottom field coil. Take a reading. This reading should be zero.

    Note: The "Minimum" button on "Calibration of a Channel" window is the default selection.

28. Enter this value in "Enter Calibration Point" field.

29. Click on "OK".

    Leave the DC current probe that is hanging on this conductor for the next reading. The system will process the calibration. The system will automatically raise the current to approximately five amps. The system will prompt you to "Enter Calibration Point" for "Bottom Field Coil Current" again.

30. Take another reading for the bottom field coil.

31. Enter the value in "Enter Calibration Point" field.

32. Click on "OK".

33. Click on "Save".

34. Click on "Save" on "Calibration of a channel" window. You will hear the input contactor open. The calibration ends. You will see the message "Flash reprogrammed OK" on the window of UPSView. The message indicates that the calibration has been successfully completed.

35. To disable the connection in UPSView, click "Connection" on the menu bar. Click "Disconnect". The computer will stop receiving system telemetry.

36. Unplug the RS232 cable. Install the sheet metal that was removed from the cabinets. Close the doors for proper air flow into the system.