Caterpillar — Reverse Power Shutdown or Reverse VAR Condition - 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, as incorrect polarity may generate erroneous faults.
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 regulators part number 155-xxxx or newer, check the value in parameter :20; if very small, try increasing it until the problem is eliminated.

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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