ELECTRONIC SAFETY ACTUATOR FOR AN ELEVATOR SAFETY BRAKE AND METHOD OF DETECTING POSITION OF AN ELECTRONIC SAFETY ACTUATOR

An electronic safety actuator for an elevator safety brake, comprising: a solenoid; a permanent magnet, movable by the solenoid between a first position proximate to the solenoid and a second position distal from the solenoid; and a measurement circuit arranged to measure the inductance of the solenoid and thereby detect the position of the permanent magnet. The inductance of the solenoid is dependent on the magnetic field in which it is situated, which is in turn affected by the permanent magnet. Thus as the proximity of the permanent magnet to the solenoid changes, the inductance of the solenoid changes (increases or decreases). The change in inductance that occurs in the solenoid of an elevator safety actuator is significant enough to be measurable electronically and this measurement can be used to determine the position of the permanent magnet and thus of the safety actuator. Such measurement can therefore take the place of the mechanical switch that has previously been used and without requiring a new expensive magnetic detector to be installed in its place. Instead, the position of the actuator can be determined using the existing components together with a new and inexpensive measurement circuit as part of the actuator control circuit.