GB512788A - Improvements in or relating to three-phase electric transformer and/or choking coil arrangements - Google Patents

Abstract

512,788. Transformers; inductances; protective arrangements. SIEMENS-SCHUCKERTWERKE AKT.-GES. March 14, 1938, No 7922. Convention date June 8, 1937. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 14, 1938.] [Classes 38 (ii) and 38 (iv)] In arrangements comprising polyphase transformers and/or choking coils wherein harmonics of the order 6n Π1 are compensated or balanced out by associating a star-connected winding 1, 2, or 3, Fig. 1, with a delta or a zigzag-connected winding 4, 5, or 6, a plurality of windings of each of the two necessary types of connection are employed and their connections to the mains R, S, T are so distributed that inequalities in the amplitudes of the harmonics associated with each phase due to asymmetry of the cores (e.g., due to the cores limbs being in one plane) are balanced out. Fig. 2 shows an alternative arrangement in which the delta or zig-zag connected windings 10, 11 are energized from secondary or tertiary windings 13, 14 inductively associated with star-connected windings 7, 8, and a star-connected winding 12 is energized from a secondary or tertiary winding 17 inductively associated with a delta-connected wiriding 9, the connections of the windings 7, 8, 9 of the mains R, S, T being arranged in accordance with the invention.