ARMATURE MOVEMENT DETECTION APPARATUS AND ARMATURE POSITION ESTIMATION APPARATUS FOR AN ELEVATOR BRAKE

摘要

In an armature movement detection apparatus for an elevator brake, an electric current caused to flow through a brake coil is detected by a current detector. A voltage applied to the brake coil is detected by a voltage detector. An abnormal voltage drop occurring in a constant voltage source for energizing an electromagnet is detected by a voltage variation detector. A movement detector detects movement of an armature relative to the electromagnet by comparing an estimated induced electromotive force and an estimated instantaneous electromagnetic power with set threshold levels and by judging whether or not the abnormal voltage drop has been detected by the voltage variation detector.