As shown in the illustration, what is the purpose of the main contacts of contactor "1S"? EL-0012

Correct Answer: Option B — The "1S" contactor connects the autotransformer in wye configuration during the starting/acceleration period.

In an autotransformer starter, the '1S' contactor serves to connect the transformer windings in a wye configuration during the initial starting phase. This reduces the voltage applied to the motor terminals, limiting inrush current. Once the motor accelerates, the '1S' contactor opens, and the run contactors engage to apply full line voltage.