Direct fault tripping of circuit breaker having solid state trip means

Claim 1

A circuit breaker including cooperating contact means; main conductor means in series with said contact means; an operating mechanism operatively connected to said contact means; a latch means normally maintaining said mechanism latched in position for opening and closing said contact means; first means for monitoring currents flowing in said main conductors means; second means including solid state circuitry for processing signals generated by said first means; third means for releasing said latch means to automatically trip said mechanism thereby opening said contact means responsive to a trip signal generated by said second means when fault currents of predetermined magnitude and character flow in said main conductor means; said third means being operatively constructed and positioned relative to said main conductor means so that as a result of magnetic coupling, magnetic flux generated by severe fault currents flowing in said main conductor means acts directly on said third means for actuating the latter to release said latch means prior to receipt of said trip signal by said latch means; said third means including an operating means, spring means urging said operating means to a trip position for releasing said latch means, permanent magnet means for holding said operating means in a latched position against force exerted by said spring means, and an actuating coil operatively positioned whereby current flowing therein generates a flux which bucks flux of said permanent magnet whereby said permanent magnet releases said operating means when said trip signal is applied to said third means; and magnetic director means operatively positioned to control direct magnetic coupling between said main conductor means and said permanent magnet.