UPS 1000S/ UPS 1200S Uninterruptible Power Supplys Caterpillar

UPS flywheel bearings must be changed due to wear and vibration. Optimally, the bearings should be changed every 3 years. A bearing may need changed earlier in system service life.

There are several indications of bearing wear that indicate a need for bearing replacement:

• Vibration

• Temperature

• Increase in operational noise level

Note: Bearings are always changed as a top and bottom set. The bottom bearing is changed first, then the top bearing is changed.

Note: Before you begin, the flywheel cabinet must be offline, de-energized, and the flywheel at zero RPM. Have the appropriate replacement parts and tools at hand to perform the bearing change.

All UPS 1200 units are equipped with Version G3.0 bearings.

ReferenceRefer to Special Instruction, REHS4885, "Procedure to Convert from G3.0 Load Cell to G3.5 Load Cell" for instructions to convert to Version G3.5 bearings.

Bearing Change Pre-removal steps

Bearing service is always performed on both the upper and lower bearings.

Note: Always change the lower bearing first, then change the upper bearing.

Note: These steps are defined for electrical high risk maintenance of the cabinet components located behind the locked doors. Follow these steps before performing maintenance on internal components. A shutdown of all input, both AC and DC, to the Flywheel Cabinet for this operation is necessary. The customer load will be unprotected.

Note: This cabinet has two sources of voltage. Control AC voltage and the DC Bus.

1. Brake the flywheel. Execution of this command can be performed using the Ctrl-X keystrokes in UPSView.

2. Turn the keyswitch to the Spindown/Offline position.

3. Transfer the UPS/SMS or MMU to bypass mode. The UPS/SMS or MMU needs to be put into the bypass mode before any work is done to the cabinet. Refer to Testing and Adjusting, "Transfer to Bypass Mode".

4. Discharge the DC Bus. Let the DC Bus purge down to below 24VDC.

5. Open the doors of the cabinet by using a 5/16-inch hex key on the upper and lower latches.

6. Disconnect the DC bus by using the DC Disconnect Handle on the middle metal safety shield.

   Note: Verify that the green light is on before operating the DC Disconnect Switch Handle.

7. Open the circuit breaker (CB1) located on the lower left panel on the CSHV cabinet.

8. Discharge the capacitors by allowing the capacitor banks in the UPS/SMS or MMU to purge down for 10 minutes.

9. Remove the lower shield, middle shield, fan shield, and the bottom cabinet frame rail.

10. Remove the middle fan to gain access to the metal cover over the top flywheel upper bearing.

11. Remove the metal shield between the two flywheels to gain access to the lower flywheel upper bearing and upper flywheel lower bearing.

Bearing Change Post-removal steps

1. Replace the metal shield between the two flywheels.

2. Replace the metal cover over the top flywheel upper bearing.

3. Replace the middle fan.

4. Replace the lower shield, middle shield, fan shield, and the bottom cabinet frame rail.

5. Close the circuit breaker (CB1) located on the lower left panel of the Clean Source High Voltage (CSHV) cabinet.

   Note: Verify that the green light is on before operating the DC Disconnect Switch Handle in the next step. Do not operate the switch if the red light is on.

6. When the green light is on, close the DC Disconnect Switch using the DC Disconnect Handle on the middle metal safety shield. Closing the DC Disconnect Switch will connect the DC Bus to the UPS/SMS or MMU.

7. Close and Lock the doors of the cabinet by using a 5/16-inch hex key on the upper latch and lower latch.

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Illustration 1	g01284002

8. Using UPSView, update the installation date of the bearings in the UPS/SMS or MMU firmware for each flywheel with bearings that were replaced.

9. Take the UPS/SMS or MMU to "Online Mode" via the GUI or UPSView. Refer to the, "Transfer to Online Mode" section of this manual for more information.

10. Enter the value for the Load Cell Offset in the Op. Params > Op. Group 5: > A/B: > Load Cell Offset menu in UPSView.

11. Enter the value for the Load Cell Serial Number into the Op. Params > Op. Group 5: > A/B: > Load Cell Serial Num menu in UPSView.

12. Enter the value for the Load Cell Calibration Factor into the Op. Params > Op. Group 5: > A/B: > Load Cell Serial Num. menu in UPSView.

13. Enter the value for the Load Cell Calibration Factor into the Op. Params > Op. Group 5: > A/B: > Load Cell Cal. Factor menu in UPSView.

14. Calibrate RPS advance set point. Refer to the, "RPS Advance Setpoint Calibration" section of this manual for more information.

15. Keyswitch the Flywheel Cabinet to the "Online" position.

    Note: The bearing change is now complete.