GB995168A - Improvements in or relating to high-tension transformers - Google Patents

Abstract

995,168. Transformers. BRATISLAVSKE ELEKTROTECHNICKE ZAVODY NARODNY PODNIK. Feb. 21, 1963 [Feb. 21, 1962], No. 6933/63. Heading H1T. The dimensions of a high-tension transformer may be reduced by the use of insulating pressure rings 3 (Fig. 2) which include capacitative rings 1, 2 and have walls acting as voltage barriers for the end coils 4. The outer insulating side wall may be bulged out to receive the supply cable 6 (Fig. 2). The end coils, treated with synthetic resin, and the capacitor rings 1, 2, are cemented into the insulating ring 3 to avoid ionisable gaps. The inner capacitor ring, inside the pressure ring, may have a channel section 2 (Fig. 4) filled with solid insulating material to form a base for the end coils. Since parts of lower dielectric stress need less insulation, a multiple-stepped inner wall and tapering outside wall (Fig. 5) may cover the end coils. The walls can be extended by cementing on insulating rings 7, 8 (Fig. 6), or laminate cylinders (Fig. 9, not shown) on the outer edge of the coils may be sheathed with a resin-coated, glass or glass-mica tape, or sprayed resin (Figs. 10, 11, not shown). The capacitative rings 4 may be made of metal, semi-conductor, or a combination of conducting and non-conducting materials. The casting materials (e.g. polyesterepoxide, silicone or silicone-rubbers), compounds (e.g. polyester-epoxide resin or silicone elastomers) and binders (e.g. epoxys or silicone resin) have fillers (e.g. fused quartz, chopped fibres or fabric of glass, or mica) to increase the mechanical and dielectric strengths and the thermal conductivity of the insulation. Treatment of the coils with such compounds during or after the winding process, can be effected in vacuum or under pressure, if necessary by centrifugal means.