GB865019A - Improvements in or relating to transformers - Google Patents

Abstract

865,019. Transformers. WESTINGHOUSE ELECTRIC CORPORATION. Oct. 23, 1958 [Oct. 30, 1957], No. 33937/58. Class 38 (2). One or both of the windings of a high-voltage transformer consist of a number of coils 18, 19, 20 in series, each coil being divided into two or more layers 14 of conductors with an oil duct 17 between them, the spaces between the coils and surrounding them being filled up with solid insulation to exclude pockets of dielectric liquid. The coils 18, 19, 20, which are connected at their lower ends, may diverge as shown in Fig. 1 so that the amount of separation is proportional to the voltage gradient between them. The conductors in the layers forming a coil may be transposed at the centre 21 to avoid circulating eddy currents. The solid insulation between the low-tension winding 15 and the high-tension winding 18, 19, 20 may be of U members and bevelled sheets of press-board and the leads may be taken out through insulating channels 54 (Fig. 9). The voltage gradient at the edges of the coils is reduced and concentration of electrical stress is prevented by the use of edge strips composed of conductors 26 (Fig. 7) surrounded by enamelled wire and paper insulation. To protect against surge voltages static plates consisting of metal foil washers 35 (Figs. 4 and 5) between pressboard washers 34, 37, are provided and may be edged with tape 36. A core shield 51 (Fig. 1) composed of copper foil 48 between insulating sheets 49, 50 may be wrapped round the core and a similar shield 52 may be arranged between the H.T. and L.T. windings.