Myford super 7 lathe tripping consumer rcd

One practical tip Dave omitted to mention. Keep one hand in your pocket while testing live circuits - it’s safer that way.

Nobody has commented on the need for a centrifugal switch on a capacitor start motor which is what the 2 brown wires are. Not a thermal switch ! 4 wires on the windings are red / black, the run windings and blue/ yellow the start windings. Wire yellow through the capacitor then through the Centrifugal switch then out to terminal 2 on Dewhurst reversing switch. Blue out to Terminal 6 on dewhurst. Black to Term 5, red to term 7. Live to term 1 on dewhurst, blue to term 2 and neutral to terminal 3. Terminals 4 and 8 are not used. If the notation on the dewhurst reversing switch is wrong swap over the wires on terminals 2 and 6. RCDs trip due to an imbalance in incomings and outgoings, an MCB will trip due to current above its rated value. A spit phase starting motor can draw 1200% above rated run current. That's where a DOL may save a motor, as it will take the starting current for a few seconds before a sustained high current will cause it to drop out. Noel.

What brown wires?
What about the two blue wires on the Stator?

I'm not sure how you can tell what wire is what unless you are psychic. Even if we knew the motor make and model the wire colours could change during production lifespan. I can't even tell for sure what the winding colours in the photo are.
As a minimum the windings need a proper isulation test, all the crimps need re-making (which will probably make them too short) and ALL existing wiring replaced and connected correctly. I'm pretty sure the OP is nor equipped do do all that. No work done previously by someone who used yellow/green wire for live and neutral connections can be trusted.

A new motor is cheap compared to the time required never mind the cost of the workshop burning down or someone being killed or injured by electric shock. Even a minor shock around running machinery can cause uncontrolable movement of body parts into moving parts or sharp tools.

Tha old, probably worn out motor / can of worms is not worth repairing. I have the knowledge, tools, parts and test equipment required and I would not even atempt to repair that motor if it was mine. I think it is irresponsible to give the OP advice other than to get a professional to look at it.

Robert G8RPI.

Noel,

For my money the red/blue and red/black wires are the centrifugal switch, you can see the contacts in photo 2 of Nicks last post.

Nick,

You can't use those blue crimps in such a confined space nor leave all the exposed copper visible, especially those chocolate block blue and brown wires.

If 'rats nest' was how you bought it, then someone knew the motor was bad. Bin it and buy a new one, they have much more room in the connector box.

If you do go 3phase, be aware the VFD doesn't normally work straight out of the box.

Lovely use of green and yellow wire.

Maybe fixable IF you have suitable test gear, or at a push it’s but a few minutes of work using terminal blocks, an incandescent lamp and a 13A plug. But as ever you really have to know what you are doing.

Look on the bright side, the motor originally wired in that manner would probably kill you...now you have something to sell on eBay as an antique, or if you have morals, something for the scrap man.