Caterpillar — Gain Setting - Adjust

Adjustments · CDVR PID / gain parameters

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

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Procedure

1. Starting with the factory defaults (Kp = 200, Ki = 600, Td = 0, and Kg = 50), adjust Kg to achieve the desired response. If that response is not achievable, proceed to Step 2.
2. Perform a "step of reference" test by recording the generator terminal voltage with a chart recorder or similar device. Limit the step sizes to 5% or less of terminal voltage.
3. If the response is too slow, increase Ki. If the response is oscillatory or has a large amount of overshoot, decrease Ki or Kd.
4. If the desired response is still not achievable, proceed to Step 3.
5. If T'do and Te are known, use the PID calculator in order to obtain the starting PID values.
6. If T'do is known but Te is not known, use the PID calculator with the default exciter time constant (Te = T'do/6).
7. Start with Kp = 10, Ki = 2, Kd = 2, Td = 0, and Kg = 30. Increase Kg until the machine terminal voltage is approximately equal to the set value.
8. Reduce Ki to 0.01; the terminal voltage should decrease. Adjust Kg in order to obtain 90% of set terminal voltage.
9. With Kg set as determined in Step 4, set Kp = 40, Ki = 10, Kd = 10, and Td = 0. Perform a "step of reference" test, with no more than 5% per step.
10. Adjust Kp to achieve 80% of the final value in the desired time frame; then increase Ki in order to get the desired response. If overshoot or ringing occurs, reduce Ki and then increase Kp, Ki, and Kd

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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