Which device ensures that no voltage is present at the motor during idle periods?

The correct answer is that a disconnect switch ensures that no voltage is present at the motor during idle periods. A disconnect switch is specifically designed to safely isolate the electrical supply to a motor or other equipment, providing a means to effectively cut off power when the motor is not in use. This is crucial for maintenance and safety, preventing accidental energizing of the motor when personnel are working on it.

In contrast, while a contactor is also used in motor control circuits, it primarily operates as a remote-controlled switch that can open and close the circuit based on control signals. If a contactor were used during idle periods, it might still leave the motor connected to the power supply, leading to potential safety issues.

A timer, on the other hand, is generally utilized to control the duration of operation rather than to isolate devices from voltage. It can determine when motors start and stop based on timing sequences but does not inherently provide a safety disconnect when the motor is not in operation.

An overload relay protects motors from drawing too much current and overheating but does not disconnect power to the motor during idle periods. Instead, it disconnects the motor if it detects an overload condition during operation.

Overall, the disconnect switch is essential for ensuring complete disconnection of power during idle