View Single Post
Old 26th Nov 2021, 4:01 pm   #5
Lucien Nunes
Lucien Nunes's Avatar
Join Date: Apr 2008
Location: London, UK.
Posts: 2,168
Default Re: Vintage 1/4 horsepower induction motor

There mighe be some confusion here. Repusion and repulsion-start motors don't have sliprings, they have a commutator on which run a set of brushes that are shorted together but are not connected to the supply. The stator is energised from the supply. On a full-time repulsion motor the brushes remain in circuit; on an RSIR they are thrown off by centrifugal gear that also puts a shorting ring around all the commutator segments to simulate a cage rotor for running.

The OP's motor seems to be a conventional induction motor but 'inside out' as he puts it, with the energised (primary) winding on the rotor and a non-energised (secondary) winding on the stator. Motors with both rotor and stator wound, with the rotor brought out to sliprings, were common in larger sizes (5hp up) to enable rotor-resistance starting. This improved the starting torque by raising the power-factor of the rotor current at high slip. But invariably, the stator winding would be the primary and the rotor the secondary, not least because of the option to disengage the brushgear after shorting the rotor in a manner similar to the RSIR.

I cannot work out the advantage of the OP's motor's configuration nor its specific starting method. Does it have some kind of pole-shading? I can hardly think that would offer superior torque to a split-phase stator, nor can I see that the brushgear would have lower maintenance requirements than the tried-and tested centrifugal starting switch.

E2A I do have some Met-Vick and AEI catalogues of the era that will be worth a trawl. There was some cross-branding within AEI so it might technically be a BT-H product, which will be evident from its general construction. I might have a look for patents on starting methods once we know more about it technically.

Fascinating. Pics needed!
Three anodes good, six anodes better!

Last edited by Lucien Nunes; 26th Nov 2021 at 4:18 pm.
Lucien Nunes is offline   Reply With Quote