GB619477A - Improvements in or relating to automatic electric circuit breakers - Google Patents

Abstract

619,477. Electromagneto. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Dec. 12, 1946, No. 36722. Convention date, Sept. 7, 1945. [Class 35] [Also in Group XXXVII] The electro-magnetic tripping device of an automatic circuit-breaker comprises a sealed tube movable with the core of the electromagnet, the tube containing means for delaying the tripping of the circuit-breaker and being arranged, to be held substantially stationary during the tripping movement of the core. The core assemblage 159 comprises a non- magnetic outer tube 167 and a non-magnetic sealed inner tube 169 containing oil, the tube 167 being secured to a magnetic core 171 which normally rests on a part 157 of the yoke 155. A core 175 is biassed by a spring 177 against a stop 179 on the tube 169, which normally rests on a main core 183 supported on an adjusting screw 185. A spring 193 surrounding the tube 167 is initially compressed between a flange 195 and projection 199 thereon. On a light overload, e.g. up to 700 per cent normal load current, the core 183 and tube 169 move upwards compressing a spring 187. By means of co-operating projections 197 and slots, the tube 167 is also moved, whereby a pin 173 thereon trips the circuit-breaker with a time delay produced by the flow of oil through an orifice 181 in the core 175 which remains stationary. On a medium overload, e.g. 700 per cent to 1000 per cent normal, the core 171 and tube 167 are moved rapidly upwards until arrested by the engagement, of the spring 193 -with the projections 197. Thereafter, the tubes 167, 169 move up under the joint action of cores 171, 183 to trip the circuit-breaker with a reduced delay. On overloads over 1000 per cent normal, the tube 167 and core 171 are moved up with sufficient force to compress the spring 193 and trip the breaker instantaneously without the time-delay device coming into effect.