GB632148A - Improvements relating to electric induction apparatus - Google Patents

Abstract

632,148. Transformers. BRITISH THOMSON-HOUSTON CO., Ltd. July 23, 1945, No. 18793. Convention date, July 28, 1944. [Class 38 (ii)] An electric induction apparatus such as a high-voltage oil-immersed transformer with insulation closely surrounding and substantially enclosing the winding turns is provided with an internal perforated member having spaced walls 36, 37 forming a chamber 35 extending substantially around and outside the winding turns 25 and inside the insulation, with a tubular member 40 forming a passage communicating between the internal chamber 35 and the outside of the insulation in order that gaseous impurities may be withdrawn from the winding. The perforated chamber is preferably made of electrically conductive material in order to serve also as an electrostatic shield. The low voltage winding 11, concentric with the high voltage winding, surrounds a winding leg 12 of a core and, as shown, the windings are separated by insulation 32 which is wound through and around the annular high voltage coil 25 which consists of a number of concentric conductor layers. Certain of these layers may be further insulated in the manner described in Specification 19750/43, as open to inspection under Sect. 91. The core and coil construction are enclosed within a relatively closely fitting casing, Fig. 1 (not shown), provided with an insulating horn or bush 16, Fig. 1, enclosing a terminal construction comprising a tube 41 which communicates with the tube 40 and extends practically the full length of the insulating bush, almost to a terminal 19 Fig. 1, on an end cap. The tube 40 may be made of conductive material and connected at its inner end to the end of the adjacent winding layer, its outer end being connected by a conductor 43 to the terminal cap. Air is exhausted from the casing through the insulating bush prior to the admission of oil through an aperture at the lower end of the casing. U.S.A. Specification 2,297,606 also is referred to.