ECONOMICALLY EFFICIENT METHOD FOR DOUBLE-LEVEL CONTROL OF AC ELECTROMAGNETIC SWITCHGEAR AND CONTROL GEAR (ALTERNATIVES) Russian patent published in 2001 - IPC

FIELD: electrical engineering; ac switch-gear and control gear for miscellaneous pieces of equipment. SUBSTANCE: proposed method is distinguished from existing methods by two modes of controlling switching-device sucking coil at dc current interrelated by gate dependence. During first turn-on stage of device pushing the start button throws the latter on line by applying primary- circuit dc current. During second stage releasing the start button automatically holds the device in economically efficient mode of power consumption by applying secondary-circuit dc current. EFFECT: enhanced service life. 3 cl, 4 dwg