Patent ID: 8228146

Claim:
A safety switch for monitoring a state of a protection device, comprising: a switch housing with a switch head; an actuator interacting with said switch head in a closed state of the protective device to signal the closed state of the protective device; and a tumbler device with a tumbler element axially movably mounted in said switch housing and releasably locking said actuator with said switch head in the closed state of the protective device, said tumbler device having at least one permanent magnet generating a magnet force retaining said tumbler element in at least one of a first position in which said tumbler device locks the closed state of the protective device and a second position in which said tumbler device unlocks the closed state of the protective device when a power supply to the safety switch is turned off, said tumbler device having at least one electromagnet generating a magnetic force when energized to transfer said tumbler element between said first and second positions, said permanent magnet being located in an axial direction within axial extents of said tumbler element and said electromagnet such that said permanent magnet, said tumbler element and said electromagnet overlap in a radial direction, magnetic flux of said electromagnet weakening the magnetic force of said permanent magnet on said tumbler element by said magnetic flux of said electromagnet being opposite magnetic flux of said permanent magnet to allow said tumbler element to move to the other of the first and second positions.