Brook Crompton single phase motor damage

borntofight00 · Apr 2, 2020

This is my first post in this forum so first of all, hi everyone! I would appreciate your help in repairing the Brook Crompton single phase motor from a Fobco Star pillar drill which has been given to me recently. As you can see in the photo, the thin metal ‘plate’ with white half-cylindrical plastic part was damaged. One side is terminated with a yellow wire, which then goes to the 'AZ' termination stud, on the other side, a yellow wire from the winding was connected with push-on crimp terminal. What is the purpose and principle of operation of this metal ‘plate’ (also, what’s the correct wording)? How can I fix it because I’m guessing that there is no chance to buy such a part anywhere?

TDegenhart · Apr 2, 2020

That is part of the motor starting circuit. The end opposite the wire once had a electrical contact that made a circuit with the bottom part in the second photo. This applied power to the start circuit to get the motor going, then when it is near full speed, that contact is opened.

I would take the motor to a motor repair shop that may be able to replace it, but more than likely you will have to replace the motor.

Tom

Jersey John · Apr 2, 2020

As Tom says above I think your best bet is to place the motor. As Brook Crompton is very common in the UK you shouldn't struggle too much.

Consider putting an advert on "Home Workshop". You may well be very surprised

John

SomeoneSomewhere · Apr 2, 2020

You might also be able to use a potential relay to disconnect the start winding instead of the centrifugal switch. Just bypass the switch.

This only works with a cap start motor; if it is split phase (resistance difference between windings), you would need to use a current-operated version.

rons · Apr 2, 2020

It looks to me like the mounting position on the phenolic board broke off. If that was my motor I would cut out a new phenolic piece and remount all the parts again.
It can be done if you have the time.

borntofight00 · Apr 4, 2020

Thanks for the answers, normally I'd take it somewhere to repair it properly, but in the current situation (lockdown) everything is closed. John, do you mean putting an advert to find someone to repair??

SomeoneSomewhere, this is not a cap start motor, could you give me a hint how could I use a relay (with timer)?

Rons, yes, it is the part of phenolic board broken, unfortunately, a copper / metal strip is damaged as well so probably the entire part needs replacing

Do you guys think this can be solved by using an external relay? If so, can you please direct me a little bit?

SomeoneSomewhere · Apr 4, 2020

You would be looking at a 'Current (sensitive) starting relay'. We'd need nameplate details to be able to actually say which one. The relay coil is in series with the motor run winding, and closes the contacts for the start winding when the run winding is drawing more than about 2x rated current, opening them again when the motor is up to speed.

An easier option is a 1-2 second timer and contactor switching the start winding.

Jersey John · Apr 7, 2020

borntofight00 said:
Thanks for the answers, normally I'd take it somewhere to repair it properly, but in the current situation (lockdown) everything is closed.

John, do you mean putting an advert to find someone to repair??

Hi, no I don't mean that ... Put an advert on Homeworkshop asking if anyone has one of these motors (List type/spec and machine)

I'm sure someone will answer your request bearing fruit

John

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Brook Crompton single phase motor damage

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