Metrotropolitan Vicker Single phase motor

A friend has a Metropolitan Vicker single phase motor electric motor with TWO (2) slip rings and carbon brushes.( Not a Repulsion type) NO connection as far as he can see to the stator. The motor name plate picture which I am unable post here, says

Cat No.6001 or could be an L. Type BAL 47 Form ABL. By the name plate the motor is very old, but might have a lot of life yet. I'm in North York's, he is in Worcester. Any ideas regarding connecting the motor directly to the mains or should it have a face plate type starter. I have never seen such a motor, three slip rings and six terminals on the stator yes, is he missing some thing ? Any relevant comment / ideas will be much appreciated John

Try looking at this web page for info on slip ring induction motors. I think the only difference between two and three slip rings is that the two slip rings will only be fed by a single phase.

3 phase motors

Martin C

Edited By Martin Connelly on 26/11/2021 19:00:43

Hmm, Any photos? How big is it?

If it is slip-rings rather than a segmented commutator it must be some kind of "Inverted" induction motor. Trouble is I can't see why you would do that or how it is started. Are you sure it is a motor? It could be some kind of permanaent magnet AC generator.

There are 3 phase motors with wound rotors and slip-rings. These have power connected to the stator windings and variable resistors (rheostats) connected to the rotor to control torque and (to a lesser extent) speed.

.

Crossed posts with Martin.

I don't think the 3 phase type slipring system will work with single phase and John says no stator windings.
A inverted permanent magnet stator AC motor won't work on single phase either.

Robert G8RPI.

It sounds like a wound rotor induction motor. Is the stator 3 phase? Normally one would wire a series rheostat across the slip rings to provide variable torque. I recall these from electrical machines lectures but even in 1970 they were regarded as obsolete I think!

Definitely single phase motor as said by the details on the makers name plate, no commutator, two slip rings, two brushes. My friend will send a better picture next week. I post them here. John

I have a Met Vickers single phase motor that I understand was surplus from WWI......when I last tried it about 25 years back it worked well......and ran a small lathe very effectively. It was part of an obvious conversion of my 'RSB' treadle lathe which is also WWI vintage and apparently quite rare.

If I remember correctly at BSC Bilston we had two large pumps driven by this kind of motor and they a large tub of salt water to control the startup

H

There is a thread about this motor on another forum. The first post by 'Phil' shows a picture of the motor name plate and I would say that the motor model is type 'BA147'. (it also clearly shows its single phase)

Ian P

Hello Ian P, its Phil on the other forum I'm trying to help..

I have the electric motor repairers ultimate manual and its comprehensive "Electric Motor Repair "by Robert Rosenberg and two other very good books by Karl Wilkinson. I can recommend all three to any one really interested in electric motors winding and its connections. Might be available on E bay but not cheap. Neither of them mention a single phase motor of this type. I'm sure some one will come up with the answer. John

Bob Stevenson, I've sent you a PM. John

Well with only one stator winding it can't be capacitor-start. There is nothing you could connect to the rotor that wound give it any spacial asymmetry to start it. The only thing that would fit is if it's actually a single-phase alternator. Frankly I would just regard it as a curiosity but not attempt to run it. The world isn't short of perfectly sound induction motors of more recent vintage waiting to be re-homed surely!

OP says no connection to stator, sounds unlikely, needs to be checked

May even be an early synchronous speed motor ?

DC on to the slip rings to lock-on to mains frequency .

Back to the Metropolitan Vicker single phase motor. Basically the motor is an inside out induction motor, the rotor is the stationary part and is constructed in a similar manner to what most folk would expect a normal induction motor to be, bars front to rear and short circuited. As the motor is not mine and some 150 miles away I can't take the motor to pieces to see the rotating member, regarding the manner in which the two windings are wound or located. Hopefully a series of picture will become available later. Pleased to say it is a runner. John

Depending on how the shorting bars are arranged, may be shaded pole? How does it know which way to start?

Surely a single phase induction motor with no start windings won't start

2 slip rings is a puzzle. 3 Slip rings together with 6 Brushes for a large 50hp 3phase star delta motor with a Allen West oil filled starter control that you move the starting handle from start to run yes . 2Slip rings have found this once where there there was a 2 Phase supply on a RAF base.

More Details will hopefully provide a answer

Bee.M

Its an induction motor which has two winding and a centrifugal switch. All the single phase induction motors I have seen have bars in the rotor laminations, front to rear ,some die cast aluminium other copper if very old, linked together forming a squirrel cage. this motor is an inside one The two windings rotate with the two slip rings attached. As I said, hopefully some pictures will soon be posted on here. John

Aha, now it has a centrifugal switch? How are two rotor windings connected to two slip rings?