Metrotropolitan Vicker Single phase motor

[john fletcher 1Participant @johnfletcher1]

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

[john fletcher 1Participant @johnfletcher1]

[Martin ConnellyParticipant @martinconnelly55370]

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

[Robert Atkinson 2Participant @robertatkinson2]

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.

.

[Robert Atkinson 2Participant @robertatkinson2]

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.

[John HaineParticipant @johnhaine32865]

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!

[john fletcher 1Participant @johnfletcher1]

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

[Bob StevensonParticipant @bobstevenson13909]

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.

[Harry WilkesParticipant @harrywilkes58467]

Posted by Robert Atkinson 2 on 26/11/2021 19:16:37:

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.

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

[Ian PParticipant @ianp]

Posted by john fletcher 1 on 26/11/2021 17:58:48:

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

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

[john fletcher 1Participant @johnfletcher1]

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

[john fletcher 1Participant @johnfletcher1]

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

[John HaineParticipant @johnhaine32865]

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!

[duncan webster 1Participant @duncanwebster1]

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

[J HancockParticipant @jhancock95746]

May even be an early synchronous speed motor ?

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

[john fletcher 1Participant @johnfletcher1]

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

[John HaineParticipant @johnhaine32865]

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

[duncan webster 1Participant @duncanwebster1]

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

[Brian MorehenParticipant @brianmorehen85290]

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

[john fletcher 1Participant @johnfletcher1]

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

[John HaineParticipant @johnhaine32865]

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

[David JennerParticipant @davidjenner61726]

One thing we do not know is what the external control gear consists of. Possibly some form of variable voltage input via a variable resistance?

Interesting.

Looking forward to the tale as it unfolds!

Dave J

[Ian PParticipant @ianp]

As I mentioned earlier this motor is also being discussed on another forum. Below are some of the pictures from that thread.

Ian P

[Robert Atkinson 2Participant @robertatkinson2]

OK, A picture is worth a thousand words.
It appears to be a switch (centrifugal) start induction motor. The oddity is that it is "inside-out". The induction part is the stator and the powered winding is the rotor.
The most likely reason for this was to get around a patent. It does simplify the centrifugal switch arrangement thoough.
AC power would just be connected to the brushes as shown in the picture.

Robert.

[Ian PParticipant @ianp]

I agree the rotor mounted centrifugal switch is a neat idea but the downside is the brushes/sliprings carry current all the time.

The one picture that I thought might eleicit the most clarification is the one showing the brass plate that clearly shows the model type to be 'BA 147'.

Surely this must be in some old catalogue somewhere?

Ian P

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