If the frequency drops below the generator under frequency percentage threshold set point value, then the under frequency timer will begin timing. When the timer expires, then the generator under frequency event is made active if the frequency has been below the threshold level continuously while timing. If the frequency rises above the generator under frequency percentage threshold, then the generator under frequency event will be made inactive. Timer will be reset.
If an under frequency condition is detected, then "GEN UNDER FREQUENCY SHUTDOWN" or "GEN UNDER FREQUENCY WARNING" will be displayed on the EMCP 3. in order to inform the operator of an under frequency condition.
Note: The severity of the under frequency condition will determine if a warning or shutdown event occurs.
The code for generator under frequency is generated when the EMCP 3 determines that a generator under frequency condition has occurred.
Test Step 1. TALK TO THE OPERATOR.
- Determine the conditions that caused the under frequency condition.
Expected Result:
An under frequency condition was caused by an occurrence that is known to the operator. The operator would like to put the generator set back into service.
Results:
- OK - The operator can determine the cause for the under frequency condition. The condition has been repaired, and the operator wants to put the generator set back into service.
Repair: Reset the generator set. Resume normal operation and verify that the problem has been corrected.
STOP
- NOT OK - The under frequency condition was not caused by an occurrence known to the operator. Proceed to Test Step 2.
Test Step 2. CHECK THE SET POINTS.
- View the generator under frequency and generator desired engine speed request set points. Make a note of the set points. Refer to Testing and Adjusting, RENR7902, "Electronic Control Module (Generator Set) - Configure". Compare the set points against the default set points of the particular generator set.
Expected Result:
The set points are correct.
Results:
- OK - The set points are correct for your particular generator set. Proceed to Test Step 3 for EUI engines. Proceed to Test Step 4 for MUI engines.
- NOT OK - The set points are NOT correct.
Repair: Reprogram the set points. Reset the generator set. Resume normal operation and verify that the problem has been corrected.
STOP
Test Step 3. VERIFY FREQUENCY CAN BE VIEWED AND ADJUSTED FROM THE EMCP 3. (EUI ENGINES ONLY)
Verify that the generator output frequency can be viewed and adjusted from the EMCP 3 display.
Expected Result:
The generator output frequency can be viewed and adjusted from the EMCP 3 display.
Results:
- OK - The generator output frequency can be viewed and adjusted from the EMCP 3 display.
Repair: Adjust the generator output frequency to meet site requirements. Resume normal operation and verify that the problem has been corrected.
STOP
- NOT OK - The generator output frequency cannot be adjusted. Proceed to Test Step 7.
- NOT OK - The generator frequency reads zero on the EMCP 3 display. Proceed to Test Step 8.
Test Step 4. CHECK THE SYSTEM BY USING THE SPEED POTENTIOMETER. (MUI ENGINES ONLY)
- With the engine running, adjust the generator output frequency by turning the speed potentiometer.
Expected Result:
The generator output can be adjusted to the desired frequency.
Results:
- OK - The generator output frequency can be adjusted.
Repair: Adjust the generator output frequency to meet site requirements. Resume normal operation and verify that the problem has been corrected.
STOP
- NOT OK - The generator output frequency cannot be adjusted with the speed potentiometer. Proceed to Test Step 5.
Test Step 5. CHECK THE RESISTANCE OF THE ENGINE SPEED POTENTIOMETER. (MUI ENGINES ONLY)
- Disconnect the speed potentiometer from the terminals "11" and "12" on the 2301A governor.
- At the speed potentiometer, measure the resistance of the speed potentiometer.
Expected Result:
The resistance should be adjustable between 0 and 100 ohms.
Results:
- OK - The resistance of the sensor is correct. Proceed to Test Step 6.
- NOT OK - The resistance of the speed potentiometer is not correct.
Repair: Replace the speed potentiometer. Resume normal operation and verify that the problem has been corrected.
STOP
Test Step 6. CHECK THE SPEED POTENTIOMETER HARNESS FOR AN OPEN CIRCUIT. (MUI ENGINES ONLY)
- Disconnect the speed potentiometer harness from the 2301A governor.
- Check for an open circuit. Check the resistance from the wire connected to terminal "11" of the 2301A governor to the same wire number at the speed potentiometer. The resistance must be 5 ohms or less.
- Check for an open circuit. Check the resistance from the wire connected to terminal "12" of the 2301A governor to the same wire number at the speed potentiometer. The resistance must be 5 ohms or less.
Expected Result:
Measured resistance between terminal "11" of the 2301A governor to the same wire at the speed potentiometer connector, is 5 ohms or less.
Measured resistance between terminal "12" of the 2301A governor to the same wire at the speed potentiometer connector, is 5 ohms or less.
Results:
- OK - The harness functions properly. Proceed to Test Step 8.
- NOT OK - The harness wiring with the incorrect resistance measurement has failed. Replace the failed harness from the 2301A governor to the speed potentiometer or repair the failed harness from the 2301A governor to the speed potentiometer. Resume normal operation and verify that the problem has been corrected.
STOP
Test Step 7. CHECK J1939 DATA LINK BETWEEN THE EMCP 3 AND THE ENGINE ECM. (EUI ENGINES ONLY)
Refer to the generator set electrical system schematic in the service manual. Check the data link wiring between the EMCP 3 and the engine ECM. For more information on troubleshooting the data link, refer to Troubleshooting , RENR7902, "Data Link Circuit Fault ".
Results:
- OK - The J1939 data link wiring is correct. Proceed to Test Step 8.
- NOT OK - The wiring is not correct.
Repair: Repair the data link wiring or replace the data link wiring. Resume normal operation and verify that the problem has been corrected.
STOP
Test Step 8. CHECK THE VOLTAGE INPUT FUSES.
- Check the three fuses on the AC voltage inputs of the EMCP 3.
Expected Result:
The fuses should not be open.
Results:
- OK - The fuses are not open. Proceed to Test Step 9.
- NOT OK - One or more of the fuses are open.
Repair: Check for a shorted component or damaged wiring. Troubleshoot and repair the problem. Refer to the generator set wiring diagram for your particular generator set. After the problem has been repaired, replace the fuses.
STOP
Test Step 9. CHECK THE GENERATOR VOLTAGE OUTPUT.
- Open the circuit breaker or remove the load.
- Start the engine and run the generator set.
- Measure the voltage between all 3 AC input fuses.
Expected Result:
The line to line voltage should measure the rated voltage of the generator set.
Results:
- OK - The voltages are correct and the problem remains. Proceed to Test Step 10.
- NOT OK - One or more of the voltages are NOT correct.
Repair: The wiring or the connections the are damaged. Check for damaged wiring between the fuses and the generator output bus. Refer to the generator set wiring diagram for your particular generator set. Repair the wiring or replace the wiring. Resume normal operation and verify that the problem has been corrected.
STOP
Test Step 10. CHECK THE VOLTAGE INPUT CONNECTIONS.
- Shut down the engine.
- Remove the EMCP 3 harness connector from the EMCP 3.
- Check the EMCP 3 harness connector. Refer to Testing and Adjusting, RENR7902, "Electrical Connector - Inspect".
- Check for one or more damaged wires between the EMCP 3 voltage inputs and the voltage input fuses. Refer to the generator set wiring diagram for your particular generator set.
Expected Result:
The wiring and the connectors should have been good.
Results:
- OK - NO problem was found with the connectors or with the wiring.
Repair: The EMCP 3 may have failed. A failed EMCP 3 is unlikely. Exit the procedure and perform the entire procedure again. If the problem remains, replace the EMCP 3. Refer to Testing and Adjusting, RENR7902, " Electronic Control Module (Generator Set) - Replace".
STOP
- NOT OK - The problem was with the connectors or with the wiring.
Repair: Repair the connectors or replace the wiring harness. Resume normal operation and verify that the problem has been corrected.
STOP