GB873941A - Improvements in or relating to electrical capacitative devices - Google Patents

Abstract

873,941. Multiple capacitors. DUBILIER CONDENSER CO. (1925) Ltd. Feb. 25, 1959 [April 16, 1958], No. 6532/59. Class 37. A capacitative device for use in a threephase power circuit to provide power factor correction and suppression of unwanted frequencies, comprises a casing A, Fig. 1, in which are three conductors B1, B2, B3, a dielectric layer surrounding each conductor and a capacitative unit surrounding each dielectric layer, each unit including at least three electrodes C, D, E. In the device of Fig. 1, casing A is earthed and electrodes D are connected to the casing, thereby forming the by-pass capacitors C1D1, C2D2, C3D3 of Fig. 2. Electrodes C are connected to their respective conductors B and interphase connection is made between each conductor B and a tag F on an electrode E surrounding another conductor, thereby forming the power factor correction capacitors C1E1, C2E2, C3E3. Various other connections are possible, e.g. the interphase connections may be made by connecting electrodes E together, Fig. 6 (not shown), and the device may be used with a delta-connected power source. Electrodes CDE may be of metal foil wound in a spiral with interleaved insulating strips, electrodes D, E being coplanar but displaced from each other along the length of the roll. Alternatively, E may be wound outside D which is wound outside C. Electrodes C, D may project beyond the insulating strips at opposite ends of the roll to facilitate connection thereto. An inductance may be inserted between each end of the conductors B and the casing, Fig. 4 (not shown).