GB587402A - Combined current and voltage transformer with closed iron cores - Google Patents

Abstract

587,402. Transformers. AKT.-GES.' BROWN, BOVERI, & CIE. April 26, 1944, No. 7803. Convention date, May 11, 1943. [Class 38 (ii)] In a combined current and voltage transformer the closed iron core of the voltage transformer and the primary winding of the current transformer are at the same potential and in contact all along their lengths and are closely surrounded by a common dielectric sheath except at the core yoke. The high voltage leads o of the primary current winding c pass through a conducting or non-conducting cover m, also at high potential, of a ceramic casing k and along a U-shaped core a of the voltage transformer the ends of which are bridged by a yoke b. Winding c may be at the four corners of a core a having a cross-shaped cross-section, or it may be a tube divided by longituinal slit, or formed by a number of rods connected at the ends. An insulating sheath d surrounds core a and winding b. On the straight limbs of core a are provided high voltage coils e of the voltage transformer with secondary coils f at their earthed lower ends. The secondary windings h of the current transformer on cores g may be on the limbs below coils f or surrounding coils f as shown in the left and right hand halves of the figure respectively. Compensating coils i, j may be provided inside sheath d for improving linkage between windings e, f, and an earthed conductive covering p on the curved part of sheath d rests on the metal base n of the container. The inner surfaces of sheath d may be at least partly covered by a conductive layer q. The tank is oil filled and thermo-syphon cooling may be employed. The Specification as open to inspection under Sect. 91 describes a construction in which the core a itself forms the primary winding of the current transformer, being divided longitudinally by insulation. This subject-matter does not appear in the Specification as accepted.