What do electrical interlocks use to disable the coil of a second contactor?

Electrical interlocks utilize auxiliary contacts on the contactors to disable the coil of a second contactor. This method employs integrated features of the contactors themselves, where the auxiliary contacts are specifically designed to make or break the circuit controlling the coil when the contactor's state changes.

When one contactor is energized, its auxiliary contacts will close, allowing the coil of the second contactor to be energized. However, if the first contactor is de-energized, the corresponding auxiliary contacts open, cutting power to the second contactor's coil. This setup ensures safety by preventing simultaneous operation of devices that could pose a risk if activated together, such as motors connected to different energy sources or machinery with opposing functions.

This system is preferred for its reliability and integration within existing contactor designs, contrasting with mechanical switches, pushbutton switches, or current sensors, which do not provide the same level of built-in coordination and safety for contactor operations.