Cat® Digital Voltage Regulator Caterpillar

Illustration 1	g01425622

Show/hide table

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".

Refer to Specifications, Systems Operation, Testing and Adjusting, RENR7941, "Earlier CDVR Dissimilarities " for part number information of the earlier version of the CDVR.

1. Verify that the voltage adjustment is not set too low.

   OK - If the voltage adjustment is correct, go to step 2.

   NOT OK - If the voltage adjustment is too low, adjust the voltage to the correct set point.

   STOP.

2. Verify that the under frequency set point (knee frequency) is not greater than the generator frequency.

   OK - If the under frequency set point is correct, go to step 3.

   NOT OK - If the under frequency set point is too high, adjust the setpoint below the rated generator frequency.

   STOP.

3. Verify that the generator is running at rated speed.

   OK - If the generator is running at rated speed, go to step 5.

   NOT OK - If the generator is not at rated speed, increase the generator speed to the rated level.

   STOP.

4. Determine if the system has a PMG powered or shunt powered regulator.

   For PMG powered regulator, proceed to step 5.

   For Shunt powered regulator, proceed to step 6.

5. Check for the correct input power to the voltage regulator. Refer to Specification, RENR7941, "Electrical" for input power requirements.

   OK - If the voltage is at the required level, go to step 7.

   NOT OK - If the voltage regulator input voltage is low, refer to the generator manual for PMG repair.

   STOP.

6. Verify that the potential transformer (if used) has the correct turns ratio and is supplying the correct voltage to the power input.

   OK - If the turns ratio of the power potential transformer is correct, go to step 7.

   NOT OK - Determine if the turns ratio of the potential transformer is incorrect, is sized too small, or the transformer is not supplying the correct power. If any of the previous conditions are true, replace the potential transformer.

   STOP.

7. Verify that the sensing potential transformer (if used) has the correct turns ratio and is operating correctly.

   OK - If the sensing potential transformer is operating correctly, go to step 8.

   NOT OK - If the turns ratio of the sensing potential transformer is incorrect, replace the sensing potential transformer.

   STOP.

8. Low generator output voltage may occur when operating in droop mode with an inductive load. If the low voltage condition is not caused by the droop function, go to step 9.

9. Replace the voltage regulator.