GB442709A - Improvements in or relating to the quenching of arcs - Google Patents

Abstract

442,709. Fusible cut-outs. SCHWEITZER & CONRAD, Inc., 4435, Ravenswood Avenue, Chicago, U.S.A. May 9, 1934, No. 14068. Convention date, May 13, 1933. [Class 38 (i)] The arc formed by the operation of a high tension fuse or circuit - breaker is formed between two movable terminals in an arcing-chamber containing arcextinguishing material, one end of the chamber communicating with a condensing chamber and the other being substantially closed so that the gaseous products evolved by the arc-extinguishing material are driven into the condensing chamber. The arc-extinguishing material in the arcing - chamber is brought into operation by a short circuit and is supplemented by another material to assist the extinction and to interpose an insulating medium to prevent restarting of the arc and also to operate alone in place of the first material in the case of overload and other less violent arcs. In the fuse shown, the fusible element 23 is arranged in an arcing-chamber 1 formed by a tough tube 40 in the upper end of a long glass tube 4 containing the usual retracting spring 12 and an insulating liquid 60. Sealed glass tubes 46 containing water &c. are arranged longitudinally or circumferentially close to the fusible element 23 so as to be ruptured by a violent arc and furnish the arc-extinguishing medium, a constricted orifice 43 directing the gaseous products into the path of the arc which is drawn through the orifice by an arcing tip 22 carried by a valve 20 that is blown open by the pressure due to the arc. The valve is guided by a stem 26 and allows the steam &c. to pass into a chamber 2 containing condensing plates 35. At the lower end of the chamber 1 a plug 48 with packing grooves 54 checks the passage of the gaseous products from the chamber 1 but allows the stem 49 carrying an arcing tip 55 to be drawn down freely by the spring 12 and submerged in the liquid 60 that forms the second arc-extinguishing medium and also prevents downward flow of the gases from the arcing chamber 1. In a modification, Fig. 6 (not shown), the liquid 60 partly fills the chamber 1 and the tubes 46 are dispensed with, vapour from the liquid 60 being driven through the orifice 43 to perform the arc-extinguishing operation. In this case a hollow plunger is attached to the stem 49 having a conical opening to direct the fluid inwardly as the spring 12 draws it downwards. The arcing tip 22 may be so long that it is not completely withdrawn from the orifice 43. Small holes may be formed in or beside the valve 20 to allow any of the liquid 60 that leaks into the chamber 2 during transport to drain back. The fuse wire 23 is of silver and the strain wire 24 of nickelchromium-iron alloy. The sealed tubes 46 also enable the use of liquid, powdered, or gaseous arc-extinguishing materials that may be such as to combine on mixing.