3000 hp 1800rpm, 4160v Synchronous (manufacturer Ideal) motor with 90 volt excitation system.

[Simon05511]

We just removed our motor and sent it off to the shop due to not being able to Sync. When the Rotor was removed and each of the 4 coils was tested, it was found that one of the coils on the rotor had a lower reading than the other three. Three of the rotor coils were .306-.310 ohms, and the fourth coil was .270.
My questions,
1. Would this cause the motor to not sync?
2. Is there anything we could do to help it sync? increase Dc voltage during start up?

 

[petersonra]

What do you mean by "not being able to sync"?

Synchronous just means the rotor and stator are moving at the same rpm. I don't know that if they are not in sync that the motor can even turn.

But, I am not familiar at all with synchronous motors because they are not common. Hopefully someone who knows a lot more can answer your question.