Electronic – Need help identifying wires on 3-phase single-volt AC motor (6 leads)

ac-motormotorthree phase

I'm far from an electrician. Just a guy trying to get some new life out of an existing piece of machinery.

See the image below, this 5HP motor comes from a heavy duty commercial treadmill. Based on the fact that it has no start capacitor, 6 leads, and that heavy flywheel on the right this is a 3-phase single-volt motor.

The labels originally were W,V,U but some of them were scratched off and unreadable. But there's two additional wires both black and missing labels, and the green for total of 6 wires. I've labeled the black wires A,B,C,D,E and measured them using ohms setting on a multimeter:

* A<->B: nothing
* A<->C: nothing
* A<->D: 0.6
* A<->E: nothing
* B<->C: 2.2
* B<->D: nothing
* B<->E: 2.5
* C<->D: nothing
* C<->E: 2.5
* D<->E: nothing

My questions are:

  1. how do I restore the original labels of W,V,U from the information above?
  2. if 3 wires were W,V,U and the other two had no labels remaining, what purpose are the other two wires?
  3. assuming i identify all the wires are correctly labeled, any quick way to test the functionality of this motor before wiring it to a control board?

Motor

Best Answer

It certainly appears to be a three-phase induction motor. The resistances between leads B, C and E seems high for stator resistance, but the fact that they are equal would indicate they are U, V and W. Which is which doesn't matter much. If the motor runs backwards when powered, swap two of them.

The resistance between A and D would be nearly zero if it is an over temperature switch. Both this and the B, C, E resistances could be just an indication that the meter doesn't read low resistances accurately.

I doubt that the motor will harm the controller board. I would be inclined to test the motor and controller board together rather than try to test the motor my itself.

The current on the nameplate posted by @StainlessSteelRat indicates that the "SPL" marked after 5 Hp stands for "sales person lie." That is a "peak Hp" rating that means it can produce the torque of a 5 Hp motor for a very short time prior to failing. It is really something like a 1.5 Hp motor. The measured resistances are more reasonable for 1.5 Hp.

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