NUT 8T4244 - Caterpillar

Illustration 1 g01425620
The Cat Digital Voltage Regulator presents an electrical shock/electrocution hazard. This hazard will cause serious injury or death.Service by trained personnel only.The terminals and heat sinks are live at hazardous voltages when power is applied and for up to 8 minutes after power is removed.
Ensure that the "Settings Group Support Level" parameter is set properly. If the parameter is not set correctly, the CDVR will disable and lockout excitation. Refer to the "Settings Groups" section of Specifications, Systems Operation, Testing and Adjusting, RENR7941, "Group Support Level".The information in this section also applies to the earlier version of the CDVR. Refer to Specifications, Systems Operation, Testing and Adjusting, RENR7941, "Earlier CDVR Dissimilarities " for the part number information of the CDVR.
Verify that all of the wiring is properly connected. Refer to Testing and Adjusting, "Wiring Diagrams". OK - If the wiring connections are correct, go to step 2.NOT OK - If the wiring is improperly connected or the wiring is loose, reconnect the wiring properly.STOP.
Verify that the generator is running at rated speed. OK - If the generator is spinning at rated speed, go to step 3.NOT OK - If the generator is not at rated speed, increase generator speed to the rated value.STOP.
The digital voltage regulator is PMG powered or is shunt powered. PMG power - Proceed to step 4.Shunt Powered - Proceed to step 5.
Check for correct input power to the voltage regulator. Refer to Specification, RENR7941, "Electrical", for input power requirements. OK - If voltage is present, go to step 5.NOT OK - If PMG voltage is not present, refer to the generator manual for the repair procedures and check for an open circuit.STOP.
Verify that the residual voltage applied to the power input is at least 6 VAC. OK - If the applied voltage is 6 VAC or greater, go to step 6.NOT OK - If the applied voltage is less than 6 VAC, refer to the generator manual and flash the generator field. Install blocking diodes in series with the battery in order to prevent damage to the voltage regulator and/or the battery.STOP.
Verify that the fuse is not open. OK - If no fuses are open, go to step 8.NOT OK - Replace any fuses that are open.STOP.
Verify that the CDVR is connected to 24 VDC control power. OK - If CDVR is connected to 24 VDC control power, go to step 8.NOT OK - Connect CDVR to 24 VDC control power.STOP.
Verify that the common alarm/Shutdown LED indicator on the voltage regulator is not flashing. OK - If no protective fault has caused the excitation to be turned off, go to step 15.NOT OK - If the LED indicator is flashing, open communications with the voltage regulator. Determine if a protective shutdown fault has occurred. A protective shutdown fault would cause excitation to be turned off. If protective shutdown fault has occurred that would cause excitation to be turned off, go to step 9.
If an "Exciter Diode Monitor" (EDM) fault has occurred, stop the