Cummins/Onan — Automatic Transfer Switch Test
Testing & diagnosis · Automatic transfer switch and control
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Use care when opening cabinet door. High voltages within cabinet present a serious electrical shock hazard.
Procedure
- Turn the Source Select switch to the normal source and move the bypass switch handle to the normal source position; release the Source Select switch.
- Turn the key-operated Drawout Release switch, turn the drawout crank handle counterclockwise until the test light comes on, then release the switch.
- Move the Test/Normal/Retransfer switch to TEST; generator set should start after start time delay and assume load after transfer time delay.
- At completion, move the Test/Normal/Retransfer switch to NORMAL; load retransfers after retransfer time delay and generator set stops after stop time delay.
- Turn the Drawout Release switch and turn the drawout crank handle clockwise to the limit of its rotation.
- Release the Drawout Release switch and push the Reset button.
- Move the bypass switch handle to the automatic position to return transfer switch to automatic operation.
Tools required
- Drawout crank handle Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Load does not actually transfer to generator set during this test
Source: Cummins/Onan 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.