MECHANISM FOR AUTOMATIC SWITCH Russian patent published in 1998 - IPC

FIELD: electrical engineering. SUBSTANCE: mechanism includes hand tommy bar positioned inside case and spring-loaded in direction of switching off to which lever is hinged. Contact lever turning about axis rests against it when switched on. It acts on immobile lever and stresses in closing position with self-fixation moving against effort of spring. Between tommy bar and contact level there is placed another lever that in stable position is almost straight and occupies certain position behind dead center of its both arms due to shape of straightening lever. This lever acts in similar manner during switching on and as rigid level in switched on position. Owing to loading of its hinge at almost straight angle by releasing level in direction of dead center lever gets into unstable position under action of contact lever turning backwards thanks to action of spring. This rectifies rigid connection between tommy bar and contact level as result of it arm on side of contact may turn into open position. EFFECT: mechanism is especially suitable for automatic switches of differential protection and for line protection automatic switches. 4 cl, 6 dwg