Which device in a control circuit is essential for stopping a motor?

• A. Overload relay
• B. Start-stop control station
• C. Pilot light
• D. Contactor

Answer: (B)

In the context of a control circuit designed to manage the starting and stopping of a motor, the start-stop control station plays a crucial role. This device is specifically designed to allow an operator to initiate (start) or terminate (stop) motor operation safely and effectively.

The start-stop control station typically includes push buttons for starting and stopping the motor, and it provides a direct interface for the operator to control the motor's operation. When the start button is pressed, it sends a signal to the motor control circuit to energize the contactor, allowing electricity to flow to the motor, thus starting it. Conversely, pressing the stop button interrupts the circuit, de-energizing the contactor and cutting off power to the motor, which stops its operation.

While other devices like overload relays and contactors are critical in protecting and controlling the motor, they do not directly facilitate the manual stopping of the motor in the same way the start-stop control station does. The pilot light serves to indicate the current status of the motor but does not play a direct role in stopping the motor itself. Therefore, the start-stop control station is essential for the operator to control motor function effectively.