Winds in a Three-Phase Motor

You're making me a little nervous asking such a basic question.

Well first you remove power from the leads in a safe fashion. Take a volt/ohm meter in voltage mode and verify that power is not present. Now disconnect the six wires from the terminal block. Change the meter into ohm mode and identify how the six wires become three pairs of wires. Since your motor has six wires, you have an induction motor. There is no galvanic connection to the rotor, so polarity of each winding is not needed to be known. Capriciously label each winding pair U, V & W. When you wire the rebuilt motor, if the motor runs backwards just safely swap any phase pair of windings. What was U now becomes V and what was V now becomes U.

I think there may be more problem. Since even the terminals 1 and 2 are not marked.

If one phase is reversed?

Say U1, V1 and W2 are connected to the phase? One phasor will oppose the other two. I think the matter is a bit complex. Of course it is not likely to happen if the rewinding is done correctly but then who knows

BTW: meggar the leads with the body too (let us not take a chance about the earth fault)

Some repair companies uses different colour wiring for the start and end of the winding. In other words all the terminal leads intended to be the one maybe in red, and the leads intended for the two's maybe blue. This may eliminate the one's and two's on the leads??

SB and Aldego,

Yes, most rewiring companies (all that I've used) will apply some form of dot convention to identify winding polarities. But as many electricians know, getting a single phase wired in reverse (you cannot get two reversed if you think about it) will not cause an immediate catastrophic failure. It will likely not work smoothly but if the motor is connected to power in a Wye configuration, this reversal can happen anywhere. The first step in the installation verification is getting the phase sequence correct, UVW or VUW. This will make the rotor spin clockwise or counterclockwise to correctly move the mechanical load. Then and only then do you consider if a single phase is reversed. You might conclude that a phase has been reversed if the motor sounds louder as the magnetic field flips direction causing two dead spots in the rotational B field. But even the rotor's rotational inertia will be able to permit travel through these nulls. I do recommend doing this verification without the external mechanical load connected to the motor, if possible. For the added inertia of the load may mask this phase reversal problem, causing inefficiencies in the drive and overheating.

Just a Crazy thought

Think DC... the motor has 3 windings ..

choose one and mark that coil in U1 & U2 connect a Battery 12 Vdc to those terminals and Using an old analogic Meter ...and lenz law ""An induced electromotive force generates a current that induces a counter magnetic field that opposes the magnetic field generating the current... wala...

lol try this and let me know if works...