Synchronous Motors 2

[Deansharafi]

Hi all,
Do Slip ring Synchronous motors contribute to short circuit level of a power system as do induction motors?

Thanks.

 

[rconnett]

By slip ring, I assume you are referring to the means by which the DC current is applied to the field of the motor.

Synchronous motors absolutely do contribute to the available fault - just like a generator would (electrically a synchronous motor & a synchronous generator are virtually identical).

The fault contribution of a synchronous motor would be a function of the subtransient reactance (Xd")- typically 17 -25% in most synchronous machines 600RPM+. See IEEE std 141 for more info.

 

[Mstrvb19]

Deansharafi-FYI-Synchronous motor contribution also depends on the type of stator excitation, and can often be much worse than an induction motor, particularly in cases where the excitation is supplied by a seperate battery system, and thus excitation remains during the fault.