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

Internal Component Preremoval Steps (MMS System Cabinet)

Usage:

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When servicing or repairing electric power generation equipment:

Make sure the unit is either locked out or tagged DO NOT OPERATE.
Remove all fuses.
Make sure the generator engine is stopped.
Make sure all batteries are disconnected.
Make sure all capacitors are discharged.
Make sure residual voltage in the rotor, stator and the generator is discharged.

Failure to do so could result in personal injury or death.

Brake the flywheel using the "Control-X" command.

Verify that breaking is complete.

Note: The flywheel must be at zero RPM in order to continue.

Turn the key switch on the system cabinet to the BYPASS position. Turn the key switch on all multiple module units (MMS) to the BYPASS position.

Verify that the UPS is in the bypass mode by pressing the "Home" soft key on the user interface panel. Observe the status line on the LCD.

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NOTICE

If the system does not enter the Bypass mode, Do Not Proceed with the procedure. Equipment damage or load interruption may occur. Contact your technical communicator.

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High voltage may be present. The power source must be disconnected before working on the equipment. Failure to disconnect the power source could result in injury or death. Verify that the equipment is not energized before performing any maintenance. This work must be performed by trained personnel with correct tools and procedures.

Refer to Systems Operation, Testing and Adjusting, "General Information (MMS System Cabinet)" for illustrations of the MMS system cabinet.

Close the bypass switch that is located in the I/O cabinet.

Open the output switch that is located in the I/O cabinet.

Open the input switch that is located in the I/O cabinet.

Remove facility power from the system input bus.

Discharge the capacitors. Allow the capacitors to purge for approximately 5 minutes in order to dissipate any residual energy in the following components: the bus (DC), armature leads and fuses (armature).

Note: When the flywheel is spinning, there is a DC voltage that is present in the cabinet. The flywheel should be stopped prior to Step 7 of this procedure if de-energizing the cabinet is the objective.

Unlock the door and open the door. Open the door of the cabinet by using a hex key on the latches on the right side of the door.