DEVICE FOR PROTECTING LOADS AGAINST ABNORMAL AC SUPPLY VOLTAGE Russian patent published in 1998 - IPC

FIELD: electrical engineering. SUBSTANCE: device has threshold element connected to final element. The latter also functions as protective gear and has triac whose gate electrode is connected to anode through diode bridge with field-effect transistor connected across diagonally opposite terminals of bridge; transistor gate is connected to collector of switch stage transistor incorporating series-connected resistor and voltage regulator diode in base circuit which are connected to source of field-effect transistor whose emitter is connected to storage capacitor and to two threshold elements; one of them is high-voltage threshold element and other, inverting low-voltage threshold element, both interconnected in parallel and connected through resistor to supply voltage rectifier built around diode. EFFECT: improved reliability, overcurrent and overvoltage capacity, reduced power loss across load, provision for abnormal-voltage protection during starting period. 1 dwg