VALVE GP-CHECK 1488005 - Caterpillar

service technician has successfully completed the formal service training program for the CAT UPS Series 300 Product as provided by the Caterpillar Corporate Training Center.
Use of this document also assumes that the service technician has been trained on the usage of special equipment such as meters and oscilloscopes and that these devices are calibrated to a standard recognized and traceable to the National Bureau of Standards.
When using an oscilloscope, only utilize an oscilloscope which provides electrical isolation between each channel and the trigger source. The use of an unapproved oscilloscope could result in equipment damage, de-energizing the load, personal injury, or death.
Hazardous voltages maybe present. Failure to follow appropriate safety procedures could result in personal injury or death.
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 use of test equipment may result in equipment damage, de-energizing the load, personal injury, or death.
When servicing or repairing UPS equipment, make sure all capacitors are discharged.
TOOLS
Examples of an oscilloscope and digital multimeter are:
Oscilloscope ? Tektronix THS720 with 600VAC 10x Probes
Digital Multimeter ? Fluke DMM 87111 or better
REFERENCE
For additional operational instructions and procedures, refer to the following publications:
RENR2476, Systems Operations, Testing and Adjusting, "UPS250, UPS300, UPS500, UPS750, and UPS900 Uninterruptible Power Supply"
SEBU7464, Operation and Maintenance Manual, "UPS250, UPS300, UPS500, UPS600, UPS750, and UPS900 Uninterruptible Power Supply"
Verify Gating Lead Connections
Before performing any electrical measurements or analysis type work, the service technician should "manipulate" the electrical conductors of each Gating Lead harness, one at a time, and monitor the result. If the result does not clear the error message, reseat the connectors between the Gating Lead harness and the SSI PWA circuit board. If the result clears the error message, you have determined the cause of the error messages and you should replace the Gating Lead harness (Cat p.n. 200-8331). If the result does not clear the error message, proceed with this troubleshooting guide.
Before beginning the procedure, ensure that each MMU has been de-energized or the Static Switch has been removed from the appropriate cabinet.
PROCEDURE:
Disconnect the six pairs of Gating Leads from the SSI PWA side only. Using a calibrated Digital Multi-Meter, at the Gating Lead connector measure the resistance between conductor sockets. You should record a value of 20 Ohms (+/- 4 Ohms). Note: Use extreme care when performing the resistance measurement. If you use excessive force when applying pressure with your DMM probes, against the connector sockets, you could "flare" the socket. The Gating Lead harness will have to be replaced if this occurs. Flaring the socket will result in an improper surface-to-surface mating between the connector socket and the SSI PWA connector pin.
Record the resistance value obtained in Step 1. Note the value as "A".
If the measured resistance value yields a Short Circuit condition, Open Circuit condition, or High Impedance (Greater than 24 Ohms) for any of the six