Cummins/Onan — Annual Preventive Maintenance
Maintenance · Transfer switch
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Only technically qualified personnel may perform these procedures, following the Service manual (962-0512).
- The transfer switch presents a shock hazard unless all AC power is removed. Move generator set selector switches to Stop, disconnect battery chargers from AC power, and disconnect starting batteries (negative [-] lead first) before servicing.
- Ignition of explosive battery gases can cause severe personal injury. Do not smoke or cause any spark, arc, or flame while servicing batteries.
Procedure
- Disconnect both AC power sources; turn generator set selector switches to Stop; disconnect external battery chargers and set starting batteries (negative [-] lead first).
- Dust and vacuum all controls, meters, switching mechanism components, interior buswork and connecting lugs.
- Wash exterior surfaces with a damp sponge (mild detergent and water); do not allow water to enter the cabinet.
- Check buswork and supporting hardware for carbon tracking, cracks, corrosion or deterioration.
- Check stationary and movable contacts; contact replacement is per section 4 of Service manual 962-0512.
- Check system hardware for loose connections; tighten as indicated in routine maintenance.
- Check control wiring and power cables for signs of wear or deterioration.
- Check control wiring and cables for loose connections; tighten as indicated.
- Check cabinet interior for loose hardware; tighten as indicated.
- Tighten buswork, control wiring, power cables and system hardware; retorque all cable lug connections.
- Service or replace the batteries.
- Connect starting batteries (negative [-] lead last); connect and enable both AC power sources and battery chargers.
- Verify proper operation of the battery chargers.
- Test system operation; close and lock the cabinet door.
Specs & values
- Hardware torque values and contact replacement procedures are in Service manual 962-0512 Amazon eBay $49.00.
- Lug torque requirements are in section 1 of Service manual 962-0512 Amazon eBay $49.00.
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.