Single Phase Motor Reversing Direction

[Steve A]

Good evening you sparky lot

I'm after some wiring advice on an old single phase motor for use on a lathe. Please see the attached pics. The tails have been removed for clarity. Live was connected to terminal B, neutral to AZ. Is it possible to reverse the direction of this type of motor without having to strip it down & swap the armature round?
Many thanks in advance
Steve A

 

[Top Cat]

Haven't got a clue! Sorry.

 

[littlespark]

Been a long time since I worked on motors, but I recall there being a box with 6(?) terminals in it. There were 2 or 3 links that could be interconnected differently across the 6 terminals which reversed the motor.

If this motor has only AZ and B, then I agree with TC.... "haven't a clue"

 

[Charlie_]

You need to work out which terminals are the starter winding and then swap over the terminals ..
More pics would be useful

 

[westward10]

Looks like a split phase motor from the rating plate so as above you need to reverse the connections on the start winding.

 

[Steve A]

Thanks for your prompt replies

There's no capacitor fitted to the motor. Is it right to assume the starter windings will be a smaller guage than the run windings & just swap them over wherever they terminate?

 

[MJPD29]

Looks like old style cable out of Interest what age is this motor

 

[Charlie_]

Yes deffo a split phase motor..
Is there any terminal markings?
Do you have pictures?

 

[Top Cat]

Thanks, @ferg

 

[Lucien Nunes]

It does not matter whether you alter the start or the run winding - just reverse one relative to the other. This is probably as simple as swapping over the two visible fly leads on the terminal studs (there will be others on the back) and reconnecting the supply. It is not normally necessary to open the motor or interfere with the actual windings.

I would remove the two leads from the studs - probably the two ends of the run winding - and check for continuity between them. Then check for continuity between the studs, and for no continuity from the studs to the fly leads. This will prove that swapping them over will reverse one winding only, and leave the switch correctly connected.

Terminal markings are all well and good, but I find in this class of motor, a remarkable number of 'unauthorised modifications' so it is best not to assume anything and check with a meter. Also, if you have not already done so, look on the inside of the terminal box cover. You will often find a schematic or instructions.

 

[Charlie_]

It does not matter whether you alter the start or the run winding - just reverse one relative to the other. This is probably as simple as swapping over the two visible fly leads on the terminal studs (there will be others on the back) and reconnecting the supply. It is not normally necessary to open the motor or interfere with the actual windings.

I would remove the two leads from the studs - probably the two ends of the run winding - and check for continuity between them. Then check for continuity between the studs, and for no continuity from the studs to the fly leads. This will prove that swapping them over will reverse one winding only, and leave the switch correctly connected.

Terminal markings are all well and good, but I find in this class of motor, a remarkable number of 'unauthorised modifications' so it is best not to assume anything and check with a meter. Also, if you have not already done so, look on the inside of the terminal box cover. You will often find a schematic or instructions.

Was hoping he might have some pics of the terminals which would make things very simple to advise him where and how to test

 

[Lucien Nunes]

There's one in the first post - maybe you can't view it? Only two terminals, AZ and B, each with a lead behind the paxolin and a visible flylead, hence my recommended test sequence.

 

[Charlie_]

Yes but that’s the connection for L & N.
Swapping them over will just reverse the polarity which will be seen across the whole circuit..
I thought if he could take the terminal cover off and show a picture then it would be very easy to observe if the motor is reversible and then advise what tests need to be done to ascertain which winding is which based on their respective resistances

 

[westward10]

I agree I don't believe swapping will make a difference. If you assume those studs are the end of a winding where are the others. That is a basic terminal connection enclosure line to one and neutral the other with other connections not readily accessible.

 

[Lucien Nunes]

I think the terminal picture is all there is of it. The visible leads are not the supply leads, which the OP implies have been removed, I expect them to be the two ends of one winding. You can also see other leads heading towards the hidden end of the terminal studs behind the paxolin, which I expect to be the other winding. Obviously one end of the start winding is internally connected via the switch.

Many older motors were arranged like this. BTH, for example, had a terminal cover with wording on the inside to the effect of 'To reverse motor, interchange the two leads from inside the motor body'.

It is not even necessary to know which winding is the start and which the run. If you can identify the two ends of one winding by proving continuity between them, you can reverse it.