CONFIDENTIAL TIBU4360-01

When the flywheel is spinning, the following components are energized: the bus, the armature leads, and the flywheel armature fuses.

When Uninterruptible Power Supply (UPS) equipment must be in operation to make tests and/or adjustments, high voltage and current are present.

Improper test equipment can fail and present a high voltage shock hazard to its user.

Make sure that the testing equipment is designed for and correctly operated for the high voltage and high current tests that are being made.

Reference Caterpillar publications RENR2476 and SEBU7464 for further detailed information.

PROBLEM: A UPS system error message of "SYSTEM PS1 failure" or "SYSTEM PS2 failure" is indicative of a problem with either the number one 24VDC Power Supply or the number two 24VDC Power Supply. The 24VDC Power Supplies are Caterpillar part number 200-8332 and 200-8449.

In order to isolate and confirm the problem, the following information is provided.

1. Confirm that the wire harness connectors between the appropriate 24VDC Power Supply and the Fan Monitor PWA board (J4 Connector) are not loose.
2. Using an appropriate digital VOM device, confirm the presence of Input and Output Voltages at the appropriate 24VDC Power Supply terminals.
3. If you do not have a proper input voltage to the 24VDC Power Supply, troubleshoot the Power Distribution PWA board.
4. If you do not have an output voltage from the 24VDC Power Supply, the problem could be attributed to the internal fuse within the 24VDC Power Supply having "opened".
5. In accordance with Caterpillar publication RENR2476, remove the appropriate Power Supply and then remove its exterior cover. Examine the internal fuse. If the fuse has "opened", replace the fuse (reference Table 1). If the fuse has not "opened", the 24VDC Power Supply is defective and the whole unit should be replaced.

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