GB282811A - Improvements in and relating to automatic reclosing circuit breaker systems - Google Patents

Abstract

282,811. British Thomson-Houston Co., Ltd., (Assignees of Traver, O. C.). Dec. 30, 1926. [Convention. date]. Cut-out arrangements.-In an automaticallyreclosing circuit-breaker system of the kind in which the circuit-breaker is reclosed automatically a certain number of times and (if the fault persists) is then held out, the interval between tripping and reclosure is made to increase in dependence on the degree of overload. The circuit-breaker 1 connecting two circuits 2, 3 is tripped on overload by the closure of an overload relay 7 which closes a circuit for a trip magnet 6 acting on the latch 5. The overload current also serves to drive practically instantaneously the disc 11 of an induction-ammeter element through an angle dependent on the overload. If the overload is very great the disc is driven so far that a projection 24 thereon engages with a detent 25 and no reclosure takes place. With lesser overloads, however, the disc is free to return under the action of the spring 13 and under the retardation of an induction disc brake 19, the clutch 22 of which slips in the forward movement. After a time which depends upon the angular distance the disc has been moved a pin 17 thereon re-engages with contact-springs 15, 16 and closes the circuit of a relay 9. in series with the contacts 28 of a notching relay 27. The relay 9 completes the reclosing circuit 4 for the circuit-breaker. After the circuit-breaker has been reclosed in this way a predetermined number of times the arm of the notching relay, which is energized by closure of back contacts 29 on the circuit-breaker, moves sufficiently far as to open the contacts 28 and prevent further reclosure.