Question 134Electricity & Electronics - QMED

The correct answer is A) an open auxiliary "M" contact. When the start button is pushed, it energizes the "M" contactor coil, which closes the main contacts to start the motor. However, when the start button is released, the "M" contactor coil should remain energized through the auxiliary "M" contact to keep the motor running. If the auxiliary "M" contact is open, the "M" contactor coil will de-energize, causing the motor to stop when the start button is released. The other options are incorrect because: B) a corroded contact on the disconnect switch (DS) at 'L3' would not cause the motor to stop when the start button is released, C) an open "M" contactor coil would prevent the motor from starting in the first place, and D) an open in the stop button contact would not cause the motor to stop when the start button is released.