Describe a basic start-stop motor control circuit using a normally open start pushbutton, a normally closed stop pushbutton, and a holding contact.

• A. Pressing start energizes the coil via the NO pushbutton; the holding contact latches the circuit, ensuring continued operation after release; pressing stop or opening the overload unloads the coil.
• B. Pressing start de-energizes the coil and releases the latch.
• C. The holding contact prevents energization of the coil at all times.
• D. The stop button energizes the coil when pressed.

Answer: (A)

The key idea is to create a self-latching control that keeps the motor running after you press start, until someone presses stop. In this arrangement, the normally closed stop pushbutton sits in series with the circuit, so opening it breaks the current and stops the motor. The normally open start pushbutton provides the initial energizing path when pressed. The holding (auxiliary) contact is wired in such a way that, once the coil energizes, this contact closes and creates a parallel path to the coil, so the coil remains energized even after the start button is released. Pressing the stop button—or an overload opening the circuit—will break that path and de-energize the coil, stopping the motor and releasing the latch. This setup explains why pressing start energizes the coil, the holding contact latches the circuit to maintain operation, and pressing stop unloads the coil to stop the motor.