Principle of operation of undervoltage disconnectors for circuit breakers

The undervoltage striker is a coil with a strike foot in the centre that snaps onto the traction bar of the circuit breaker mechanism so that the mechanism is always unlocked, ensuring that it is impossible to store energy to close the circuit breaker. (Forcing an energy storage close at such a time would break the traction bar.) When the coil receives enough voltage, the striking foot is suctioned and exits the traction bar’s trajectory, so that the circuit breaker can be closed and divided normally.