Marathon — Drying Electrical Insulation - Short Circuit Method
Maintenance · Windings
From a Marathon service manual — check it applies to your exact model before use.
Before you start
- Be sure all steps are performed and all precautions taken as personal injury or serious damage could result.
Procedure
- Disconnect exciter leads F1 and F2 from the regulator.
- Connect battery or DC source of approximately 20-35 volts to exciter leads F1 and F2.
- Short circuit generator output lead wires to each other (L1 to L2 to L3).
- Start generator and measure current through output leads with clip-on ammeter.
- Adjust voltage source to approximately 80% of rated AC nameplate amps.
- Check insulation resistance every one to four hours until constant value obtained.
- Remove short circuit, disconnect DC source, reconnect F1 and F2 leads at regulator.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 20-35 volts DC source
- 80% of rated AC nameplate amps
Source: Marathon 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.