CT saturation when starting an induction motor


Thread Starter


Dear All,

During the starting of induction motor, it draws 5-6 times the FLA. so how come the CT reacts to it i.e, how the Ct reflects the ratio as the ampere drawn is more than the Ct's Primary rating?
Chazree... the fact that starting-current exceeds a CT’s nominal rating has no deleterious impact on the CT! However, this statement presumes:

1) The selected CT-ratio conforms to the motor’s nameplate NEMA Design Code Letter (Inrush-kVA/Hp ratio.)

2) The starting-time (breakaway to rated speed) is in the order of a few seconds.

Regards, Phil Corso