GB471300A - Improvements in electric circuit breakers having arc quenching arrangements - Google Patents

Abstract

471,300. Liquid - blast switches. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Dec. 30, 1936, No. 35757. Convention date, Jan. 2. [Class 38 (v)] A circuit-breaker with extinguishing chambers provided with a differential piston for achieving two oppositely-divided streams in contact with the arc, has the chambers divided into three spaces by two adjacent intermediate walls provided with holes for the passage of the movable contact, one space being bounded by the larger surface of the piston, another by the smaller surface of the piston, and the third being in communication with the space outside the chamber. The cylindrical extinguishing chamber 3 is provided with a cover 6 and contains two concentric cylinders 8, 12 having bases 9, 13 in which are tightlyfitting holes for the movable contact 2. Cylinder 12 is attached to the inturned part 11 of a cylinder 10 secured to cover 6, and cylinder 8 is secured to a cylinder 20 which is fastened to the cover 6 and apertured at 24. A differential piston 21 has a collar co-operating with the cylinder 10 and a collar 23 co-operating with parts 11, 20, and acts, when depressed against the spring 35, to drive gas-free liquid from the space 18 between cylinders 8, 12 across the arc as soon as the openings in bases 9, 13 are uncovered by the contact 2 after it has separated from fixed contact 1. The arc-pressure is communicated initially to the piston through a bore 32 in the contact 2 and through holes 24. The blast flows from space 18 into spaces 17, 16, escaping from the latter through valves 15 if the pressure is adequate. Valves 25 are provided also in the cover 6. In Fig. 2 (not shown), the base 9 is normally pressed against base 13 by means of a spring acting on the cylinder 20, this pressure being overcome when the blast-pressure is adequate. In this form also, valves are located in between the space 18 and the piston. In Fig. 3, the piston is formed by a double cylinder 44, 45 having bases 46, 47, and apertures 48 leading to the upper surface of a collar 49 forming part of the piston. The space between the cylinders 44, 45 leads to holes 42 in the guide cylinder 38 with an inturned part 39. A collar 57 with relief valves 54 is secured to cylinder 38, and a wall 55 is fixed to the support 50 of the fixed contact 1. In breaking circuit, the initial pressure forces the piston downwards to compress the liquid in space 53, and when openings in 46, 47 are uncovered, liquid escapes from that space and from space 56 into the inter-cylincler space, escaping through openings 42.