VOLTAGE-CONTROLLED STARTING RELAY FOR INDUCTION MOTOR

摘要

There is provided a voltage-controlled electronic relay for starting a singl e- phase induction motor, which includes: a power supply unit 310, configured of a bridge diode BD, for supplying power to circuit elements of the starting relay when AC power of the induction motor is turned on; a triac 306 for applying the AC power to a starting coil W3 of the induction motor or cutting off the AC ; power; a signal input unit 322 f or sensing a voltage induced to the starting coil; a hysteresis unit 324 for outputting a n ON control signal at tile initial starting stage, generating an OFF control signal for turning off the switch when the induced voltage sensed by the sensing element reaches a predetermined OFF reference voltage, and generating the ON control signal for turning on t he switch again when the induced voltage becomes lower than a predetermined ON referen ce voltage during a normal operation period; and a triggering unit 330 for turning on t he switch according to the ON control signal of the hysteresis unit and turning off th e switch according to the OFF control signal. Accordingly, impulse noise generated across the triac is removed using a spark killer and stabilized voltage is provided to the circuit elements.