Generac — Generator Tests Under Load

Testing & diagnosis · Transfer switch and generator under load

From a Generac service manual covering: RTSC400A3, RTSW300A3, RTSW400A3. Check it applies to your exact model before use.

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Procedure

1. Set the generator main circuit breaker to OFF (OPEN).
2. Set the utility service disconnect circuit breaker of the transfer switch to OFF (OPEN), and turn OFF (OPEN) all load circuit breakers.
3. Manually actuate the transfer switch main contacts to the emergency (STANDBY) position.
4. Select MANUAL mode to start generator; allow engine to stabilize for a few minutes.
5. Set the generator main circuit breaker to ON (CLOSED).
6. Turn on electrical loads to the full rated wattage/amperage capacity of the generator. DO NOT OVERLOAD.
7. Check voltage and frequency across transfer switch terminals E1 and E2.
8. Verify gas pressure remains within acceptable parameters.
9. Allow the generator to run under rated load for at least 30 minutes.
10. Set generator main circuit breaker to OFF (OPEN) when checkout under load is complete.
11. Allow generator to run at no-load for several minutes; then shut down by selecting OFF.
12. Move main switch contacts to utility position.
13. Set transfer switch utility service disconnect circuit breaker to ON (CLOSED).

Source: Generac 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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