If the voltage drops below the generator under voltage percentage threshold or the automatic voltage regulator (AVR) request set point value, the under voltage timer will begin timing. When the timer expires, the generator under voltage event is made active (if the frequency has been below the threshold level continuously while timing). If the voltage rises above the generator under voltage percentage threshold, the generator under voltage event will be made inactive. The timer will be reset.
If an under voltage condition is detected, "GEN UNDERVOLTAGE SHUTDOWN" or "GEN UNDERVOLTAGE WARNING" will be displayed on the EMCP 3. The message is used to inform the operator of an under voltage condition.
Note: The severity of the under voltage condition will determine if a warning or shutdown event occurs.
The code for generator under voltage is generated when the EMCP 3 determines that a generator under voltage condition has occurred.
Test Step 1. TALK TO THE OPERATOR.
- Determine the conditions that caused the under voltage condition.
Expected Result:
An under voltage was caused by an occurrence 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 voltage 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 voltage 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 following set points:
- Generator under voltage
- Automatic voltage regulator (AVR) desired voltage request
- Generator AC monitor
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.
- 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 VOLTAGE CAN BE ADJUSTED.
Verify that the generator output voltage can be adjusted from the EMCP 3 display.
Expected Result:
The generator output voltage can be adjusted from the EMCP 3 display.
Results:
- OK - The generator output voltage can be changed from the EMCP 3 display.
Repair: Adjust the generator output voltage to meet site requirements. Resume normal operation and verify that the problem has been corrected.
STOP
- NOT OK - The generator output voltage cannot be adjusted. Proceed to Test Step 4.
Test Step 4. CHECK CAT DATA LINK BETWEEN THE EMCP 3 AND THE VOLTAGE REGULATOR.
Refer to the generator set electrical system schematic in the service manual. Check the data link wiring between the EMCP 3 and the voltage regulator. For more information on troubleshooting the data link, refer to Troubleshooting , RENR7902, "Data Link Circuit Fault ".
Results:
- OK - The data link wiring is correct. Proceed to Test Step 5.
- 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 5. VERIFY VOLTAGE SENSING CIRCUITS.
Verify that all three phases of generator output voltage are shown on the EMCP 3 display.
Expected Result:
All three phases of generator output voltage are shown on the EMCP 3 display.
Results:
- OK - All three phases of generator output voltage are shown on the EMCP 3 display.
Repair: Refer to appropriate voltage regulator service manual and perform an operational check of the voltage regulator. Resume normal operation and verify that the problem has been corrected.
STOP
- NOT OK - All phases of voltage are not shown on display. Proceed to Test Step 6.
Test Step 6. 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 7.
- 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 7. 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 8.
- 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 8. 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