GB846083A - Improvements in or relating to electrical capacitors - Google Patents

Abstract

846,083. Capacitors. DUBILIER CONDENSER CO (1925) Ltd., DUBILIER, W., and COURSEY, P. R. Sept. 5, 1956 [Sept. 5, 1955], No. 25416/55. Class 37. A capacitor comprises metallised strips A 1 of PTFE or like fluoro-carbon material, each having a generally central fold D 1 (Fig. 1), sandwiching in contact with the metallised surface C<SP>1</SP> a projecting metal foil strip B <SP>1</SP>, the fold D <SP>1</SP> of each dielectric strip extending to or nearly to the edges opposite the fold of the dielectric strip A<SP>2</SP> sandwiching the foil B<SP>2</SP> of opposite polarity. Polychlortrifluoroethylene may be used instead of PTFE. Aluminium deposition may be used with aluminium foil or silver coating with copper or silver-plated copper foil. The preferred embodiment comprises two strips overlapped as in Fig. 1 and wound on a ceramic tube having metallised ends to which the inner layers of projecting foil are soldered. End caps (Figs. 4, 5) having a tubular projection J2 are attached by soldering through the slots J <SP>1</SP>. Stacked capacitors may be made by transverse zig-zag folding or by cutting the strips into short lengths. Casings. Fig. 6 shows a casing, which may be hermetically sealed, comprising an insulating tube K to which are fixed metal ends L having an annular rib to locate a metal tube N into which the projection J<SP>2</SP> may engage to provide support and connection for the winding. Alternatively, the end-caps J may be dispensed with if contact is made between the metallised end of the ceramic tube and the annular rib. Space is left for circulation of a cooling medium such as a low loss silicone compound having high dielectric strength. Multiple units., Fig. 7 shows three seriesconnected capacitors mounted in a casing comprising a metal base Q<SP>2</SP> soldered or otherwise hermetically sealed to an insulating cover P. The base forms one terminal. Connections are made by metal tubes N; the upper capacitor makes contact with a terminal Q The tubes N are perforated to allow the cooling fluid to flow through the ceramic tube on which each capacitor is wound. Alternative intermediate connectors R may be carried by insulators R I attached to the inner walls of the case. A filling plug Q4 is provided in the base.