Abstract: In a safety system for an elevator, slip detection means detects a slip between a drive sheave and a main rope. A safety gear is mounted to a car, the safety gear being electrically operated by an actuator to cause the car to make an emergency stop regardless of whether a running direction of the car is upward or downward. A safety gear controller cuts power supply to a hoisting machine motor and causes the safety gear to make a braking operation upon detection of the slip between the drive sheave and the main rope by the slip detection means.

Abstract: A power converting apparatus used as an active filter includes single-phase multiplex inverter unit for converting DC power into AC power and a control unit for controlling the single-phase multiplex inverter unit. The single-phase multiplex inverter unit includes a first single-phase inverter and a second single-phase inverter. The first single-phase inverter to which a maximum DC voltage is supplied outputs voltage pulses at a rate of one pulse per half the period of an AC voltage fed from an AC source. The control unit includes a pair of hysteresis comparator circuits for driving the second single-phase inverter such that an AC source current follows a sinusoidal target current.