Sounds like you have a permanent capacitor run motor. Running hot under no load is pretty characteristic of the breed. Excellent at their design job but not a general purpose motor. Ages back I fitted one to a pillar drill which eventually fried itself mid-way through a long series (50??) of fairly small holes (3/16).

Post mortem research revealed that this type of motor are a sort of "synthetic 2 phase" machine despite the single phase supply and very efficient at their design speed, load and slip angle. Unfortunately any change in slip angle as when running off load or with more than the design load rapidly upsets the synthetic 2 phase business so motor efficiency drops signifcantly and things become hot'n bothered. Often fatally.

A major application for these machines is driving continous or near continously running fans. Once up to speed the load settles very close to the design rating so the motor is happy, running all the time the extra efficiency relative to a standard single phase motor means smaller electricity bills. No centrifugal switch simplfies the design too making for a cheaper motor.

Clive

Hi Vernon,

Could you post diagrams of the way it was wired originaly when it "Worked fine". The way it is wired now (Needing help to start) and the way it was wired with the reversing switch when it ran hot. A diagram of how the motor that failed was wired to the reversing switch would also help understand the paths between connections on the switch in each of its three positions.

Les.

Hi Vernon,

I assume you mean live when you say + and neutral when you say – (+ an – are on DC supplies the mains is AC ) The way you have it wired could be right or you could have the windings mixed up. This is why I wanted to know how it was wired when it worked properly. I would expect the winding that should have the capacitor in series with it to be the winding with the higher resistance.

Les.