[Phil G4SPZ]

I can’t think of anyone else who might be able to help. Does anyone know anything about induction motors? A friend of mine has found an old model engineer’s lathe which he hopes to get going, and he has asked me to check out the motor. It has been decades since I studied electrical machines but I haven’t come across a motor quite like this before. It’s a 1/4 horsepower Metropolitan Vickers single-phase motor and I think it might be quite old.

Essentially, the motor has a wound rotor with centrifugal starting switch, and two slip rings which connect to spring-loaded carbon brushes held in the terminal block. But... the stator windings have no terminals and no apparent connections to the supply. It’s almost like a ‘squirrel cage’ or split-phase design, but inside-out. An extensive Google search has drawn a complete blank.

I have Megger tested it and it seems fine, and the rotor windings test okay, but am reluctant to apply power to the brushes without fully understanding the design.

The nameplate details are attached. Any advice you can offer will be greatly appreciated!

Phil