GB538672A - Compressed air circuit breaker having a resistance bridging the contacts - Google Patents

Abstract

538,672. Gas-blast switches. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. March 20, 1940, No. 5178. Convention date, March 30, 1939. [Class 38 (v)] The main-contact bridging resistance 8 of an air-blast switch is connected in circuit by an auxiliary arc between contacts 5, 7 which are opened either by the air-blast, or by a spring after the extinction of the main arc. In Fig. 1, the resistance is introduced by a contact 9 which is moved about pivot 9a by the air-pressure acting on a piston 10, which pressure acts through the nozzle contact 2 to draw the auxiliary arc by moving the contact 5 which is mounted on a contact 3 carried on arms 4. In Fig. 2 (not shown), contact 1 is in sliding engagement with a contact connected to one end of the resistance, and contact 5 is in the form of a spring-controlled disc which is guided on a conducting stem so as to rise under the air-pressure and engage contact 7 and then move past it to draw the auxiliary arc. In Fig. 3, contact 5 is formed with an armature 19 co-operating with a horseshoe magnet 22 energized by the current in rod 21 to which 5 is pivoted. Initially a comparatively high current is required to close contacts 5, 7, but when the current is low or the main arc is extinguished, the air-blast assisted by the spring 24, or the latter by itself, opens the contacts. The Specification refers also to a separate air current operating the auxiliary contact.