GB520601A - Improvements in and relating to electric fuses - Google Patents

Abstract

520,601. Electric cut-outs. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 14, 1938, No. 33077. Convention date, Nov. 13, 1937. [Class 38 (i)] [Also in Group XXXVII] In a high tension fusible cut-out of the expulsion type, a soldered connection and one or more pairs of contacts which are opened mechanically are arranged in series, the gases formed by the arc at the soldered connection acting to quench the arcs formed at the contacts. In Fig. 1, the terminal 2 is connected through a cap 4 and nut 3 to a rod 5 which is soldered at 1 to a rod, 6. At the lower end of the rod 6, a contact stud 7 fits in a hollow contact 8, connected to the terminal 9. The soldered connection 1 is enclosed in a sheath of material which gives off gas at a low temperature and the cartridge tube 10 has a lining 15 which emits gas under the action of an arc. On fusion of the joint 1 the resilient cap 4 lifts the rod 5 starting an arc and the gases evolved drive the plug 7 and rod 6 into the lower section of the cartridge and also extinguish the arc formed between the contacts 7 and,8. The plates 13 guide the plug 8 into a trap 11 provided with a resilient pad 14 and arcing directly between the contact 8 and the rod 6 is prevented by an insulating coating 17. The gases escape from the cartridge tube through a filter 12 consisting of thin parallel sheets a small distance apart parallel to one another. In Fig. 2, there are five pairs of contacts and a soldered connection. The contacts 7 are connected alternately by conducting rods 24 and non-conducting rods 25. The hollow contact of the first and second pair and of the third and fourth pairs are connected by external conductors 23 or by fuses. When the soldered connection fuses an arc is formed and extinguished at each of the five pairs of contacts: The contacts m'ay be so arranged that the arcs form one after the other. Specification 509,331 is referred to.