SEAL-RING 7K1509 - Caterpillar

Illustration 1 g00643710
System Schematic For AC Transformer Box (ATB)
When the engine-generator, or any source to which the engine-generator is synchronized to, is operating, voltages up to 600V are present in the control panel.Do not short these terminal with line voltage to ground with any part of the body or any conductive material. Loss of life or injury could result from electrical shock or injury from molten metal.
The display of the GSC is showing 0 volts or 0 amperes for one or more AC phases with the genset that is running and the load that is connected.For AC voltage problems, begin troubleshooting at step 1.For AC current problems, begin troubleshooting at step 4.
Check the fuses.
Check the three fuses on the AC transformer box (ATB).The fuses should not be blown.Expected Result: The fuses should not be blown.Results:
OK - Fuses are OK. Proceed to next step.
NOT OK - One or more of the fuses are blown. Check for a shorted component or wiring error. Troubleshoot the fault and repair the fault. See the "Generator Set Wiring Diagram" in Testing And Adjusting, "Schematics and Wiring Diagram". STOP.
Check the generator output.
With the engine running and the circuit breaker open or the load removed, measure the voltage between all three fuses on the ATB.Expected Result: The line to line voltage should measure correctly for all three phases.Results:
OK - The voltages are correct and the problem remains. Proceed to next step.
NOT OK - One or more of the voltages are NOT correct, the wiring or connections are faulty. Check for wiring errors between the ATB and the generator buss, see the "Generator Set Wiring Diagram" in Testing And Adjusting, "Schematics And Wiring Diagram". Also check the electrical connections at the ATB terminal. See Testing And Adjusting, "Electrical Connector Inspection". STOP.
Check the connections.
Stop the engine.
Check the harness connector and crimp terminals of the ATB.
Check the GSC harness connector. See Testing And Adjusting, "Electrical Connector - Inspect".
Check for one or more broken wires between the ATB and the GSC. See "Generator Set Wiring Diagram" in Testing And Adjusting, "Schematics And Wiring Diagrams".Expected Result: All connectors are OK and the problem is no longer present.Results:
OK - All connectors are OK and the problem is no longer present. This procedure has fixed the fault. STOP.
NOT OK - Problem remains and concerns AC voltage. It is unlikely that the GSC is faulty. Replace the ATB. If the problem persists, then replace the GSC. STOP.
NOT OK - Problem remains and concerns AC current. Proceed to next step.
Check the current transformers.
Stop the engine.
At terminals 51, 52 and 53 of the ATB, disconnect only the wires that lead away from the ATB. These disconnected wires go to the current transformers (CT1, CT2, and CT3).
Measure the resistance from terminal 50 to each of the disconnected wires.Expected Result: The resistance should be less than 5 ohms.Results:
OK - The resistance is correct. Therefore, the current transformers are good. Proceed to next step.
NOT OK - One or more of the resistance measurements are NOT correct. A current transformer