GB1079449A - Improvements in and relating to electric transformers - Google Patents

Abstract

1,079,449. Transformers. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. April 30, 1964 [May 22, 1963], No. 20437/63. Heading H1T. In an electric transformer, windings 2, 3 which are mounted on a magnetic core 7 are completely enclosed in, and separated from the core 7 by, an envelope which comprises outer and inner walls 5, 6 and which contains cooling fluid, the envelope being arranged in a tank containing a second cooling fluid and being connected by a pipeline to a pump and heat-exchanger located externally of the tank. The envelope may be at least partly made of insulating material such as synthetic resin-bonded glass fibre material or may be constructed so that the outer and inner walls 5, 6 as well as the end walls comprise alternating portions of electrically conducting material such as aluminium or steel and electrically insulating material. The transformer is assembled on site by connecting stepped yoke portions of three laminated cores 5 each provided with enveloped windings which may be surrounded by dry gas during transportation to the site. The windings may be subjected to high vacuum drying and impregnation before the cooling fluid which may be oil is circulated in the envelopes. The tank which houses the envelopes and which may be of concrete and may be noise-proof and/or weather-proof is filled with air, carbon dioxide, water or oil which may be circulated. Extension portions (7, 8) (Fig. 7, not shown) may be provided in the transformer to support terminals and tap changers.