Thompson Universal motor with 3-wires. How do I wire it

[AndyNC]

Hi guys and gals,

I've been looking for a motor to drive a Unimat 2B which my father gave me many years ago and I have found a motor in another box of stuff he gave me.
It's a Thompson Houston universal Type BB1625 1/16Horse 3500rpm 230-240V

What's confusing me it that it has 3-wires and I can't Google how to connect them, most drawings show 2 or 4 wire.

Has anyone any experience on how to wire these motors.

Cheers

Andy

 

[MMUK]

Have you got a pic of the motor and wiring? Can't tell you unless we know the wiring colours. Is the cable connected to a junction box oin the motor or is it a flying lead exiting through a grommet?

 

[AndyT]

It sounds like an ordinary single phase motor, with connections to live, neutral and earth. What colours are the wires?

 

[AndyNC]

Hi,

Thanks for the responses.

I should have said that all the wires are black which causes me much confusion.
The wires come out through a grommet. There is no terminal box.

I'll post some pics later today when I get a chance.

Cheers

Andy

 

[flh801978]

It you have a meter or a continuity tester check whether one is connected to the chassis of the motor
if so thats earth
connect the other two to supply either way round doesnt matter

if ones not earth we need more info

 

[MMUK]

connect the other two to supply either way round doesnt matter

Erm yes it does. Connecting the phase the wrong way round reduces motor power and in some cases it can run backwards (depending on motor type - Belle MiniMix 110v motors are a prime example).

 

[AndyNC]

I've looked in more detail at the motor.

On the label under cycles it has 50/DC so it can be mains or DC hence the universal.

None of the wires are connected to the case BUT two of the wires are stranded and the other is solid.
Metering between the two stranded wires indicates that there is a capacitor connected between then in that the initial meter reading is zero ramping up to approx 250ohms.
Metering between either of the stranded and the solid gives o.c.

I saw a write up of what happens if you connect the motor incorrectly.. the cap goes BANG.

Photos

Hope this helps because I'm still confused.

Cheers

Andy

Sorry, can't work out how to embed photos. The instruction on flikr don't seem to work.

 

[flh801978]

I'm sure thats just a 240v ac motor and i'm sure theres not a capacitor involved
They wouldnt have marked 50dc under the cycles

I think you will have to investigate inside to where the wires go

it will almost certainly be a series connected brush motor
one wire will go to a brush the other brush to the field coils then the other end of the field to your other wire
your solid wire not connected perhaps

 

[Deejay]

Morning Andy

Pictures ...

picture-posting-guide-t63716.html

Cheers

Dave

 

[dickm]

From memory (daughter in the USA uses a Unimat for jewellry work) there IS a capacitor in their motors. It's an odd beast, centre tapped to earth for interference suppression, AFAIK. When I got her lathe, the cap burned out almost immediately, killing the motor, and it was a pig to find a proper replacement (probably impossible). Think in the end it was a matter of carefully inserting two caps wired in series.
Daughter is in the UK at the moment, but when she gets home, could probably check the wiring for you.

Otherwise, if you can locate Bob (9fingers) who used to post on this forum, he would almost certainly have an instant answer.

 

[Deejay]

Otherwise, if you can locate Bob (9fingers) who used to post on this forum, he would almost certainly have an instant answer.

He is usually available over on The Wood Haven

http://thewoodhaven.co.uk

Cheers

Dave

 

[MMUK]

The Thompson Universal motors do have a capacitor start so it's important to connect the wires the right way round.

You need to whip the cover off and see which is connected to the cap. For ease of use in the future, I'd wrap a bit of red tape around this wire, it's the positive and needs to be connected to your live feed.

 

[AndyNC]

Thank you all for your responses.
I'll take the motor apart shortly (I'm a bit booked over the next few evenings) and check out how it's wired and publish the results here.

dickm: The motor is not from the unimat. I do not have the original motor and am looking to use the Thompsom as an alternative.
I have one question about the unimat while we're (me anyway) on the subject. The head stock can be aligned using the washer (which I don't have) but how do you lock down the head stock, I can't find what clamps it.I could have a part missing. This lathe has been repaired so probably not complete.

Cheers

Andy

 

[dickm]

dickm: The motor is not from the unimat. I do not have the original motor and am looking to use the Thompsom as an alternative.
I have one question about the unimat while we're (me anyway) on the subject. The head stock can be aligned using the washer (which I don't have) but how do you lock down the head stock, I can't find what clamps it.I could have a part missing. This lathe has been repaired so probably not complete.

Ah, sorry, thought the Thompson was an original.
Don't quite follow your query - can you post a pic that shows what you have and what is the problem. Just to check, which Unimat is this? The old greeny-grey SL/1200, or the more modern (white?) Unimat 3. Daughter's one is the Elliot badged 1200.