Westerbeke — Checking the Main Rotor Winding Resistance
Testing & diagnosis · main rotor windings
From a Westerbeke service manual covering: WTA 15, WTA 20, WTA 25, WTA12KW, WTA15KW, WTA16KW, WTAl5KW. Check it applies to your exact model before use.
Before you start
- With the ground lead disconnected from the shaft there should be no continuity to the shaft.
Procedure
- With ohmmeter on Rx1 scale, place plus lead on DC output connection (red dot) point #4.
- Place negative lead to rotor shaft or rotor ground terminal.
- Read 3.0-3.2 ohm; note a shorted bridge rectifier can influence the reading.
- If variation found, isolate rotor windings by unsoldering the DC lead and lifting ground lead.
- Measure resistance with rectifier removed from circuit.
Tools required
- ohmmeter Rx1 scale Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 3.0-3.2 ohm
Source: Westerbeke 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.