Electrical – Motor wiring problem

bad-wiringmotorthree phase

The label attached to the motor

I have a bit of a problem correctly wiring up the motor on a piece of industrial equipment that was ordered from China.

When ordering I was told that it would run off of a three phase supply.
I've attached a picture showing the label with the wiring diagrams (supposedly for clockwise and anticlockwise operation) attached to the motor.

The label shows two wiring configurations. It was wired up in the first (clockwise) configuration when it arrived. Both of the configurations seem to expect a single phase supply and use two external capacitors.

The second one quite clearly just shorts the supply. The first one is less obviously stupid, but does not look like any motor wiring scheme I have seen before. But when i connected it up, the motor ran for a few seconds before one of the capacitors (rated for 450 V/AC) started smoking and the breaker tripped.

Can any one explain whats going on here and maybe give me some advice on how to wire it up correctly? Any help would be greatly appreciated!

Best Answer

It is a single-phase motor. Any single-phase motor can be run from a 3-phase supply of the proper voltage. Just connect it to any two phases. Are you sure that you connected capacitors of the proper microfarad value to the proper terminals? Are the capacitors rated for motor-start and motor run duty?

The diagram below shows what I think are the internal winding and starting switch connections. C2 must be the starting capacitor. It is not shown to be connected to the power connections, therefore it must be connected to an internal component that disconnects it after the motor reaches full speed after the power is switched on. Since the stating capacitor has a high capacitance, it allows a high current in the start winding. It is designed to carry the high current for only a about second or two. If it remains connected, it and the start winding will overheat and fail. C2, the start capacitor, should be the 250 uF capacitor and C1, the run capacitor, should be the 50 uF capacitor.

The reversing links change the polarity of the start winding with respect to the run winding. The connection diagram should show the links in only one position, not both at the same time. The motor must have the direction selection changed only when it is unpowered and not turning.

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