Cummins/Onan — Voltage Regulator (VRAS-2) Adjustment
Adjustments · Voltage regulator VRAS-2
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- High voltages in the control present an electrical shock hazard which can cause severe personal injury or death.
Procedure
- Loosen locking nut of Voltage Adjust potentiometer R21; locate adjustment screw to mid-position and retighten locking nut.
- Open controller panel doors.
- Refer to Figure 2-6 for proper Stability Range (S1) and Mode Selection (S2 and S3) switch settings.
- Ensure that all connections are proper and secure.
- Connect an accurate voltmeter to VRAS-2/TB1-2 and -3 terminals (controller without Detector AC meter option).
- Start generator set.
- Using a screwdriver, turn R32 potentiometer on VRAS-2 to increase or decrease voltage to achieve proper setting; observe voltmeter; set voltage with no load connected.
- Stop generator set, and prepare all installation and generator set controls for operation readiness.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Example: For a 120/240 volt connection, set at no-load voltage for approximately 246 volts
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.