Cummins/Onan — AC Voltage Regulator Adjustment (Rotating Exciter)
Adjustments
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
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Before you start
- Be sure engine speed is correct before attempting to correct output voltage.
Procedure
- Turn the manual field rheostat slightly clockwise to the RHEOSTAT ON position.
- Adjust the manual rheostat to obtain an exciter voltage of 70 volts.
- Shift the dc brush rig to the position giving the highest voltage.
- Turn the manual field rheostat all the way counterclockwise to REGULATOR ON.
- Set the regulator rheostat at approximately the middle of its rotation.
- Set the adjustable sliding clip resistor to obtain the rated ac voltage.
- Check that regulator range is at least 10 percent above and below rated voltage.
- Regulate the ac output voltage per the voltage chart.
Tools required
- dc voltmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 70 volts exciter across brushes A1 and A2
Source: Cummins/Onan owner's 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.