Cummins/Onan — Changing Control Accessory Panel AC System Voltage
Adjustments · Control accessory panel stepdown transformers
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Failure to remove AC power from the automatic transfer switch and to disable the generator set presents a serious shock hazard during this modification.
Procedure
- Open automatic transfer switch cabinet door.
- Move the operation selector switch to STOP.
- Disconnect the starting batteries.
- Remove AC line voltage from the automatic transfer switch.
- Remove the twist-lock disconnect plug and control accessory panel.
- Rewire the stepdown transformers T2, T3, T4, and T5 using the wiring diagram furnished with the control accessory panel.
- Change the wire lead connections on the right side of the terminal strip for the transformers.
- Rewire battery charger transformer T1 so the wire from F1-2 and T1-H5 (COM) go to the appropriate connections for the nominal AC voltage.
- Close the control accessory panel.
- Reconnect the twist-lock disconnect plug.
- Restore AC line voltage to the automatic transfer switch.
- Reconnect the starting batteries.
- Move the operation selector switch to RMT or NORMAL, whichever applies.
- Close the cabinet door.
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.