Parallel feeds to 12 Lead motor

[philly]

Two contactors - one for each winding set. Essentially two 175hp motors. Energize first contactor - motor comes part way up to speed. Energize second contactor - motor accelerates two running speed. Supposedly cuts down the inrush current and voltage drop - and it should some.

I've only dealt with one in my career. If I get a choice, that will be enough

cf

Why does the motor only come part way up to speed with the one winding set energized? Is this because the one winding only produces half of the torque and therefore the the load will have a slip where the reduced torque intersects the motor torque?

Why will there be less current during starting with only 1 winding set? Something to do with the reduced flux with only 1 winding?

 

[Cold Fusion]

Why does the motor only come part way up to speed with the one winding set energized? Is this because the one winding only produces half of the torque and therefore the the load will have a slip where the reduced torque intersects the motor torque?

Why will there be less current during starting with only 1 winding set? Something to do with the reduced flux with only 1 winding?

First a minor disclaimer: I'm out of my area on motor design so I'm guessing.

As a part winding it has turns and copper for a 175hp motor not a 350hp - so one would expect the inrush is half that of a 350Hp.

As for coming up to part speed, yes, I suspect the timers are set to hit the second winding when the speed is such that the total current for both windings does not exceed the first set inrush.

cf