460v motor winding resistance

[winnie]

One cool thing that can be observed is the voltage drops across the resistor and the reactor, when added together, will be more than the source AC voltage. This is because the currents will be up to 90 degrees apart.

Totally off topic: if you put an inductor in series with a capacitor, then the voltage drops will be 180 degrees out of phase (nearly 180 degrees with real components). The voltage drop across the individual components can be much higher then the total voltage drop.

Taken to the extreme of selecting the frequency where inductive impedance matches capacitive impedance and you have resonance. The voltage can get extremely high; this is the principle of the Tesla Coil.

Slight correction to the above: in a series circuit all current has to be the same and in phase. It is the voltage across the individual components which is out of phase. The currents being out of phase describes a parallel LR circuit.

Jon

 

[TwoBlocked]

I sit corrected. After all, I am at a desk.

 

[Joethemechanic]

Can't you use a low-voltage or a variable transformer for motor-winding testing?

But really for induction motors I always figure a megger test is sufficient. If there is an open, or high resistance, and the motor has been in service, chances are it's got an insulation fault also. Then it's time for a teardown and visual anyway