GB709114A - An improved thermal over-current electric circuit-breaker - Google Patents

Abstract

709,114. Automatic circuit-breakers; switchboards. ELLENBERGER & POENSGEN GES. May 10, 1951 [May 10. 1950; July 10, 1950], No. 11000/51. Class 38(5) [Also in Group XXXVI] A circuit-breaker comprises a spring-controlled contact bridge held in the " on " position by a bimetal strip which is heated by the controlled current and carries a contact at its free end cooperating with the contact bridge, the circuit also being completed at a second point. In one form, Fig. 1, an insulating slidable block 11 carries contacts 19, 20 engageable with a fixed contact clip 9 and a contact 10 on the bimetal strip 8, respectively. The strip 8 normally latches the block 11 in the closed position but, when it deflects due to the current through it, releases the block 11 which is guided by a pin 12 and a projection 15 engaging a slot in a rail 16. The circuit is reclosed by depressing a button 13 and the breaker may be tripped manually by pressing a button 21 having an enlarged end 24 engaging a sloping part 25 of the strip 8. In a modification, Fig. 10 (not shown), the clip 9 is replaced by a bimetal member which increases the contact pressure on current increase, and the strip 8 has a heating coil. In a further modification, Fig. 11 (not shown), clip 9 is replaced by a contact strip bent over at right angles. In a further form, Fig. 12, a conducting plunger 30 carries a contact disc 29 co-operating with the contact 10 on strip 8 and is guided in a casing 39 having a bayonet-fixing 34. In a modification of this arrangement, an insulating sleeve is placed around rod 30 below the contact disc so as to prevent premature contact between 10 and 30 on cooling of strip 8, the circuit being reclosed only on depression of rod 30. Switchboards. A number of circuit-breakers may be arranged side-by-side on a base-board having pressed-in sleeves co-operating with pins on the breakers.