Caterpillar — Improper PF Regulation or KVAR Regulation - Troubleshoot

Testing & diagnosis · Digital Voltage Regulator

From a Caterpillar service manual — check it applies to your exact model before use.

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Procedure

1. Stop the generator set and check the wiring; if CT or PT polarity is incorrect, reverse the polarity.
2. Start the generator set and load with 25% to 50% of rated load using 0.8 power factor inductive load if possible.
3. Check the values in parameters :04 and :05; measure the ampere load on the B phase and the signal voltage level at terminals 5 and 6.
4. Compare parameter :52 to actual generator current; slowly decrease or increase parameter :05 until the currents match.
5. On 130-xxxx and older units check parameters :16 and :17; on 155-xxxx and newer units check parameters :36 and :37; try the default settings.
6. If the problem only exists at low power levels, check parameter :38 and try raising the value.
7. Remove the remote PF/KVAR adjust rheostat and retry. Verify CT sizing: no more than 5 VAC (RMS) at full rated load but not less than 3.5 VAC.
8. Disconnect accessory wiring from terminals 3, 5, 6, 7, 40, 41, 42, 43, 44, 45, and 50 and operate at no load to isolate a faulty accessory.

Source: Caterpillar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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