GB571119A - Improvements in and relating to high tension electric current transformers - Google Patents

Abstract

571,119. Transformers. ASEA ELECTRIC, Ltd. (Allmanna Svenska Elektriska Aktiebolaget.). Dec. 22, 1943, No. 21447. [Class 38 (ii)] A U-shaped primary winding for a current transformer consists of one or more insulated conductors 26, Fig. 4, surrounded by an inner tubular conductor or stress shield 27 and an outer U-shaped stress shield 29 with paper insulation between the central core and inner shield, and between the inner and outer shields. In a modification, Fig. 6, the inner stress shield is surrounded by alternate insulating and conductive layers (stress shields) which form steps along each leg. In a further modification, Fig. 7, additional conductive layers 34 are provided within the insulation at the coil ends. A transformer comprising a primary winding as described is enclosed in a casing comprising a lower tank 1 containing the core and winding 9, an intermediate conical insulator 2 and an upper container 3. Stress rings of semicircular section 19, 20 are arranged outside the conical insulator 2, and rings 23, 25 and shield 21 surround the upper ends of the primary coil ; the rings being in electrical contact with the outer stress shield 29 by means of clips 24, and the shield 21 in contact with the container 3 and terminal 12 by means of clip 22. The lower tank 1 may be filled with oil or an oil-sand mixture.