Missing winding 2

[JAB1961]

I have a motor that is running on 3 ph 240 volt.
I went to switch it to 3 ph 480 and found it would not run.
After checking each winding I found from 1 to 4 is open.
I put it back to the 240 and it runs.
Why is this and what is it doing to this motor?

 

[sreid]

For 240 V, the windings are in parallel. For 480 V the windings are in series. So with 1-4 open, at 240 V one phase is "Half open" but the phase is still there. At 480 V the phase is open circuit and the motor won't start because it is "single phasing" (one phase not operating) (but it pulls a lot of current).

 

[aolalde]

What Sreid explained is the reason the motor still spins while connected in parallel ( 240), however it does not mean it is 100% good, the phase currents must be unbalanced generating a considerable negative sequence which traduces in lower torque and rotor overheating.