What is a pushbutton interlock and provide an example of its use.

• A. An interlock prevents opposing actions, such as preventing both forward and reverse motor operation simultaneously.
• B. An interlock increases current to the coil.
• C. An interlock is a protective device for overvoltage.
• D. An interlock stores energy for startup.

Answer: (A)

A pushbutton interlock is used to prevent opposing actions from being energized at the same time in a control circuit. In a motor control setup with forward and reverse pushbuttons, the interlock ensures you cannot energize both contactors simultaneously. When you press the forward button, the interlock locks out the reverse path, so the motor can only run in one direction at a time. This protects the motor and the control wiring from conflicts, reduces the chance of mechanical damage, and helps ensure safe startup.

The other options don’t fit the purpose of an interlock. An interlock doesn’t increase current to the coil; it isn’t a protective device for overvoltage, and it doesn’t store energy for startup.