Cummins/Onan ATUC A 800 - 4X / 111 — Undervoltage Sensor Calibration
Adjustments · Undervoltage voltage sensor
For the Cummins/Onan ATUC A 800 - 4X / 111, from the Cummins/Onan service manual.
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Procedure
- Open the right cabinet door of the automatic transfer switch.
- Move the operation selector switch on engine control to STOP.
- Turn all the undervoltage sensor knobs to minimum voltage setting.
- Turn the PICK-UP VOLTAGE knob of the sensor to be calibrated to its clockwise limit.
- Turn the PICK-UP VOLTAGE knob very slowly counterclockwise until relay K3 picks up; reading times multiplying factor should equal line voltage.
- If setting too low: turn knob to clockwise limit then counterclockwise to desired setting; insert screwdriver in CALIBRATE hole and turn counterclockwise until relay K3 picks up.
- If setting too high: turn knob to clockwise limit, turn CALIBRATE to clockwise limit, turn knob to desired setting, then turn CALIBRATE counterclockwise until relay K3 picks up.
- Repeat for each undervoltage sensor, then make the sensor settings.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Sensor setting range 90 to 140 volts for a nominal 120-volt system
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.