GB712583A - Improvements in and relating to electric transformers - Google Patents

Abstract

712,583. Transformers. GENERAL ELECTRIC CO. Oct. 13, 1952 [Oct.11, 1951], No. 25577/52. Class 38(2) In an instrument transformer whose windings 3, 4 are enclosed in a metal container 1 on which is mounted a porcelain bush 7 through which the high tension leads 6 pass, to prevent breakage of the bush when high pressure is generated in the container under fault conditions, an insulating cylinder 11 is interposed between the leads 6 and the bush 7 and the container and space between the cylinder 11 and leads 6 are filled with coarse sand which acts as barrier to the speedy transmission of pressure to the bush 7. A wall of container 1 is provided with one or more diaphragms 24 of such rupturing characteristics that they break before the maximum pressure generated has travelled along cylinder 11. To increase its barrier efficiency, the cylinder 1, which may be of paper, optionally impregnated with a hardenable resin, projects into the container. The upper end of bush 7 is closed by a metal cap 17 which provides an expansion chamber, and is connected to the two high tension terminals 15, 14 directly and through a non-linear resistor 19 respectively. The sand not only acts as a pressure barrier, but cools the gas, and reduces the amount of liquid insulant needed. Specification 660,085 is referred to.