Electronic Modular Control Panel II (EMCP II) Caterpillar

Display of Voltage or Current Is Zero

Usage:

System Operation Description:

Zero volts or zero amperes are showing on the display of the GSC for one or more AC phases. This is showing while the genset is running and the load is connected.

Show/hide table

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.

Test Step 1. THE PROBLEM IS WITH AC VOLTAGE OR THE PROBLEM IS WITH AC CURRENT.

Determine if the problem is with AC voltage or with AC current. Check the display of the GSC while the genset is running and the load is connected.

Results:

AC VOLTAGE - Zero volts are showing on the display of the GSC for one or more AC phases. Proceed to Test Step 2.
AC CURRENT - Zero amperes are showing on the display of the GSC for one or more AC phases. Proceed to Test Step 7.

Test Step 2. CHECK THE FUSES.

Check the three fuses on the AC transformer box (ATB).

Expected Result:

The fuses should not be open.

Results:

OK - The fuses are not open. Proceed to Test Step 3.
NOT OK - One or more of the fuses are open.
Repair: One or more of the fuses are open. Check for a shorted component or damaged wiring. Troubleshoot and repair the problem. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams". After the problem has been repaired, replace the fuses.
Stop.

Test Step 3. CHECK THE GENERATOR OUTPUT.

Open the circuit breaker or remove the load.

Start the engine and run the genset.

Measure the voltage between all three fuses on the ATB.

Expected Result:

The line to line voltage should measure the rated voltage of the genset.

Results:

OK - The voltages are correct and the problem remains. Proceed to Test Step 4.
NOT OK - One or more of the voltages are NOT correct.
Repair: The wiring or the connections are damaged. Check for damaged wiring between the ATB and the bus. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams". Also, check the electrical connections at the terminal of the ATB. See Testing And Adjusting, "Electrical Connector - Inspect".
Stop.

Test Step 4. CHECK THE CONNECTIONS

Shut down the engine.

Check the harness connector and the terminals of the ATB.

Check the GSC harness connector. See Testing And Adjusting, "Electrical Connector - Inspect".

Check for one or more damaged wires between the ATB and the GSC. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams".

Expected Result:

The wiring and the connectors should have been good.

Results:

OK - NO problem was found with the connectors or with the wiring. Proceed to Test Step 5.
NOT OK - The problem was with the connectors or with the wiring.
Repair: Repair the connectors or replace the wiring harness.
Stop.

Test Step 5. CHECK THE OUTPUTS OF THE ATB

Remove the GSC harness connector from the ATB.

At the terminal of the ATB, measure the resistance between the following terminals: terminal J1-1 to terminal J1-2 and terminal J1-2 to terminal J1-3

Expected Result:

Each of the resistance measurements should be 2.0 ± 1.0 Ohms.

Results:

OK - Each of the resistance measurements is 2.0 ± 1.0 Ohms. Proceed to Test Step 6.
NOT OK - One or more of the resistance measurements is NOT 2.0 ± 1.0 Ohms.
Repair: The ATB has failed. Replace the ATB. See Testing and Adjusting Section, "EMCP Electronic Control (AC Transformer Box) - Replace".
Stop.

Test Step 6. CHECK THE INPUTS OF THE ATB

Remove the three fuses on the ATB: F11, F12 and F13

At the terminal of the ATB, measure the resistance between the following terminals: terminal T11 to terminal T12 and terminal T12 to terminal T13.

Expected Result:

Each of the resistance measurements should be 1,050 ± 100 Ohms.

Results:

OK - Each of the resistance measurements is 1,050 ± 100 Ohms.
Repair: The GSC may have failed. It is unlikely that the GSC has failed. Exit this procedure and perform this entire procedure again. If the problem remains, replace the GSC. See Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace".
Stop.
NOT OK - One or more of the resistance measurements was NOT 1,050 ± 100 Ohms.
Repair: The ATB has failed. Replace the ATB. See Testing and Adjusting Section, "EMCP Electronic Control (AC Transformer Box) - Replace".
Stop.

Test Step 7. CHECK THE CURRENT TRANSFORMERS

Shut down 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. These current transformers are CT1, CT2, and CT3.

Measure the resistance from terminal 50 to each of the disconnected wires.

Expected Result:

The resistance should be approximately 5 Ohms.

Results:

OK - The resistances are approximately 5 Ohms. Therefore, the current transformers are good. Proceed to Test Step 8.
NOT OK - One or more of the resistance measurements are NOT correct. A related current transformer or related wire is open.
Repair: Replace the CT or repair the wiring. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams".
Stop.

Test Step 8. CHECK THE OUTPUTS OF THE ATB

Shut down the engine.

Remove the harness connector from the GSC.

At the harness connector of the GSC, measure the resistance between the following contacts: contact 4 to contact 16, contact 5 to contact 16 and contact 6 to contact 16. Be sure to allow each measurement to stabilize.

Expected Result:

Each of the three resistances should be 120 ± 20 Ohms.

Results:

OK - Each of the three resistances is 120 ± 20 Ohms. Proceed to Test Step 10.
NOT OK - One or more of the resistance measurements are NOT correct. Proceed to Test Step 9.

Test Step 9. CHECK THE GSC HARNESS CONNECTOR

Remove the GSC harness from the ATB.

Check the resistance of the wires in the GSC harness for an open wire. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams".

Expected Result:

The wires in the GSC harness should measure less than 5 Ohms.

Results:

OK - The wires in the GSC harness measure less than 5 Ohms.
Repair: The ATB has failed. Replace the ATB. See the Testing and Adjusting Section, "EMPC Electronic Control (AC Transformer Box) - Replace".
Stop.
NOT OK - The wires in the GSC harness do NOT measure less than 5 Ohms.
Repair: Repair the wiring or replace the GSC harness. Verify that the repairs fixed the problem.
Stop.

Test Step 10. CHECK THE INPUTS OF THE ATB

The wires that were previously disconnected from terminals 51, 52, and 53 will remain disconnected. The only wires which are connected to these terminals should lead into the ATB.

At the terminal strip of the ATB, measure the resistance between the following terminals: terminal 51 to terminal 50, terminal 52 to terminal 50 and terminal 53 to terminal 50.

Expected Result:

All the resistance measurements should read less than 1 Ohm.

Results:

OK - All the resistance measurements do read less than 1 Ohm.
Repair: The GSC may have failed. It is unlikely that the GSC has failed. Exit this procedure and perform this entire procedure again. If the problem remains, replace the GSC. See Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace".
Stop.
NOT OK - One or more of the resistance measurements are NOT correct.
Repair: The ATB has failed. Replace the ATB. See the Testing and Adjusting Section, "EMPC Electronic Control (AC Transformer Box) - Replace".
Stop.