GB636192A - Improvements in current transformers - Google Patents

Abstract

636,192. Transformers. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 30, 1946, No. 38048. Convention date, Dec. 29, 1945. [Class 38 (ii)] In a current transformer with a core having two parallel legs each carrying a primary winding, a metal reinforcing strap is wrapped round the primary winding assembly with its axis parallel to those of the legs. Both primary winding coils 4, 5 comprise four superposed conducting strips, which at one end are connected together and to terminals 6, 7. Two of the strips 13, 13<1> make a complete turn round one of the limbs of a wound core and end in projecting terminals 14, 14<1>, while the other two strips 11, 11<1> make one and a half turns and end in terminals lying on the surface of the coils. Insulation 12, 12<1> is placed between strips 11, 11<1> and 13, 131. The two coils are assembled together with insulation 16 between their adjacent faces and terminals 14, 141 are brazed respectively to the ends of strips 11<1>, 11. There are thus two parallel paths between terminals 6, 7, each in effect comprising two turns. A reinforcing steel band 9 round the outside of both coils prevents deformation with heavy currents and acts as a magnetic screen. A modification is described in which each parallel path has three effective turns, Figs. 5, 6 (not shown).