Spindle motor rewind

[johnsattuk]

I don,t suppose that you want to rewind my HF (1000hz, 55volt) to 400hz 230volt), for a (small) bag of gold of course. This is a serious inquiry as I too have been told that it is not possible. G.

Sorry but modifying some one else's motor would be a bit scary , I persevered with mine mostly because I was told it's not possible and I could see no reason that it could not be done, just a matter of finding the correct info, I have spent a lifetime solving engineering problems, many of which were not possible.

There are motor design programs out there but they are very expensive, need to find a friendly face in one of the universities. I tried a couple of re-winders for info but they really don't want to know about anything non standard.

Modifying an existing motor should not be too difficult if you accept that the manufacturer got it right with respect to flux densities in the stator (ampere turns in old money).

This something I found somewhere on the net.

Rewinding for a change in voltage

If a 220 volt motor is to be rewound to operate on 440 volts, use twice as many turns on each coil and one-half the circular-mills area of wire. In other words, if 40 turns of NO. 17 wire were used on the original motor, 80 turns of NO. 20 should be used on the new motor

Some motors rated for 230 volts will not handle the load on 208 volts if loaded to the maximum. The turns must be reduced to the ratio of the voltage change. As an example, 230-volt motor has 40 turns: 230/208 = 1.1, 40 turns/1.1 = 36 turns. If there is enough room, the next larger wire size should be used. An easy way to determine whether there is enough room is to cut the required number of of lengths of wire of this size and fit then into the slot.

Changes for New frequency

There are two ways to convert these motors; one keeps the same horsepower for the new speed, and the other keeps the same torque for the new speed (more horsepower). For the same horsepower, use the following formula: old turns*Sqrt(old Hz / new Hz) = new turns. If you want the same torque then it is: old turns*old Hz/new Hz = new turns.