Undervoltage tripping, combined with an emergency-off button, provides fail-safe tripping. The MN release is continuously supplied, i.e. if supply is interrupted:
either voluntarily, by the emergency-off button, or accidentally, through loss of power or faulty wiring,
the release provokes opening of the circuit breaker.
The MX release opens the circuit breaker via an impulse-type (u 20 ms) or maintained order.
When the MX release is supplied, it automatically opens the circuit breaker. Opening is ensured for a voltage U u 0.7 x Un.