GB546399A - Improvements in electric compressed air blow-out switches - Google Patents

Abstract

546,399. Gas-blast switches. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET June 9, 1941, No. 7262. Convention date, June- 7, 1940. [Class 38 (v)] In a gas-blast switch having normal-load carrying contacts 3, 4 and arc-quenching contacts 8, 9 in parallel therewith, the blast-gas flowing past, or the current flowing in, the contacts 3, 4 directly governs the contactoperation whereby the latter contacts are not opened before the former. In Fig. 1, the main fixed contact 3 is of nozzle-shape and the male movable contact 4 carries a pin 5 engaging a contact 6 on a fixed arm 7 to which is pivoted the contact 8 connected by insulating link 12 to the differential piston 13. Normally the contact 8 is in the position shown and, in opening the switch, is moved by the blast-gas acting on the smaller surface of piston. 13 so as to engage 9. When contact 4 opens the nozzle 3, the pressure acts also on the larger piston surface and an arc'is drawn between 8, 9 and blown against auxiliary electrode 16 mounted on a metal grid 17. The part of the arc between 8, 16 is thus shunted by the resistance 15. Several modifications in detail are also included, Figs. 2-5 (not shown), such as arranging a magnet in one of the main leads so as to attract an armature and hold contact 8 in engagement with contact 9, and arranging contact 8 as a reciprocable plunger contact in a separate insulating container, the contact having a piston surface for effecting its movement.