Faults that are discussed in this section will not cause excitation to be turned off unless one of the following is true:
- Some external means of removing excitation is wired into the "Alarm" output driver
- Some external means of removing excitation wired into the "Shutdown Fault" output driver
Shutdown faults that always cause excitation to be turned off are discussed in the Testing and Adjusting, "No Voltage - Troubleshoot" section. Open communication with the voltage regulator in order to determine which fault condition has occurred.
A constantly lit "Fault" LED indicates that the "Alarm" output driver is active. A flashing "Fault" LED indicates that the "Shutdown" output driver is active.
If an "Excitation Loss" (reverse VAR) fault has occurred, a reverse VAR condition has been detected. A "Excitation Loss" fault occurs when the input exceeds the programmed threshold for longer than the programmed time delay. If an incorrect fault detection is suspected, verify that the programmed settings are compatible with the application. Even if the settings are correct, there is a possibility to have an incorrect fault detection. The fault can occur if the generator voltage and the generator current sensing inputs to the voltage regulator are not properly wired for ABC rotation. Verify correct wiring of the generator voltage and generator current sensing inputs to the voltage regulator. Refer to the Testing and Adjusting, RENR7941, "Wiring Diagrams" section.
If a generator over voltage fault has occurred, a generator over voltage condition has been detected. The over voltage is detected at the generator voltage sensing inputs of the voltage regulator. A fault has occurred when the input voltage is in excess of the programmed threshold for longer than the programmed time delay. Refer to the Testing and Adjusting, RENR7941, "High Voltage - Troubleshoot" section.
If a generator under voltage fault has occurred, a generator under voltage condition has been detected. The under voltage is detected at the generator voltage sensing inputs of the voltage regulator. A fault has occurred when the input voltage in excess of the programmed threshold for longer than the programmed time delay. Refer to the Testing and Adjusting, RENR7941, "Low Voltage - Troubleshoot" section.
If the" Fault Reset" contact input is closed for more than 10 seconds, a "Fault Reset Too Long" fault has occurred. Remove the short across the "Fault Reset" contact input.
Reset the voltage regulator by either of the following:
- Momentarily close the "Fault Reset" contact input
- Cycle the 24 VDC control power