Electronic Modular Control Panel II (EMCP II) For MUI Engines Caterpillar

Illustration 1	g00487968
System Schematic For Generator Fault Relay (GFR)

The GSC uses the generator fault relay (GFR) to activate the shunt trip coil of the optional circuit breaker during a shutdown fault. This circuit breaker takes the generator off the line during a shutdown fault. The GFR is located within the relay module. The optional circuit breaker is located in the generator housing and the shunt trip coil is located within the circuit breaker.

Note: Whenever the GSC activates the GFR, "K2" is shown on the lower display. "K2" is also shown on the lower display when the GSC attempts to activate the GFR. When the GFR is not activated, "K2" is not shown.

Procedure

The possible cause of this diagnostic code is an open coil or a shorted coil of the GFR.

The following response is the system response to this fault while the GFR is activated:

• If a CID 442 occurs, then there is no effect on the system because the optional circuit breaker is already open. Also, the shutdown mode is functioning. The generator is already off the line.

The following response is the system response to this fault while the GFR is not activated and a shutdown fault occurs:

• If a CID 442 occurs, then the GFR cannot activate the shunt trip coil of the optional circuit breaker. The generator remains on-line.

The GSC treats a CID 442 as an alarm fault. Active alarm faults are shown on the display when the alarm codes key is pressed. Also, the active alarm faults are shown when the ECS is in any position except the OFF/RESET position. Clear the diagnostic code from the fault log after troubleshooting is complete.

1. Check the status of the diagnostic code (Active/Inactive).

   1. Turn the ECS to OFF/RESET and then turn the ECS to STOP.

   2. Press the alarm codes key.

   3. Observe the upper display. Check that the diagnostic code is showing.

   4. If the diagnostic code is not showing, enter the service mode. View the fault log (OP1). Check that the diagnostic code is showing.

      Expected Result: A CID 442 FMI 12 is showing as a active fault or an inactive fault.

      Results:

      • No - A CID 442 FMI 12 has not occurred (NOT active and NOT inactive). STOP.

      • Yes - A CID 442 FMI 12 is active or inactive. Proceed to 2.

2. Check internal cable of relay module.

   Note: Only open the relay module in a dry environment. If the inspection takes more than twenty minutes replace the desiccant bag in the GSC housing. See Testing And Adjusting, "Relay Module - Replace".

   1. Turn the ECS to OFF/RESET.

   2. Temporarily, remove the relay module from the GSC. See Testing And Adjusting, "Relay Module Replace".

   3. Check the cable that attaches the relay module to the GSC.

      Expected Result: The cable should be firmly seated in the connector. The clamp should be in place. The cable should not be damaged.

      Results:

      • OK - Reassemble the relay module to the GSC. Proceed to 3.

      • NOT OK - Replace the connector clamp if it is missing. If the cable is damaged, replace the GSC. STOP.

3. Perform a functional check for the GFR.

   1. Turn the ECS to OFF/RESET.

   2. Disconnect all wires from RM-22 of the relay module.

   3. At the relay module, measure the resistance from RM-22 to RM-7. Resistance should be greater than 5000 ohms.

   4. Turn the ECS to STOP and push in the emergency stop button.

   5. At the relay module, measure the resistance from RM-22 to RM-7. Resistance should be less than 5 ohms.

      Expected Result: For 3.c, the resistance should be greater than 5000 ohms. For 3.e, the resistance should be less than 5 ohms.

      Results:

      • OK - It is likely that a temporary bad electrical connection existed and this troubleshooting procedure corrected it. Check the electrical connectors, terminals and wiring. See Testing And Adjusting, "Electrical Connector - Inspect". STOP.

      • NOT OK - Either one of the resistance measurements are NOT correct. The relay module is faulty. Replace the relay module. See Testing And Adjusting, "Relay Module - Replace". STOP.