GB1037414A - On-load tap-changing equipment for an electrical transformer - Google Patents

Abstract

1,037,414. Electric transformers. BRUSH ELECTRICAL ENGINEERING CO. Ltd. March 8, 1963 [March 10, 1962], No. 9327/62. Heading H1T. In on-load transformer tap-changing equipment in which a static switching element is used for the diverter switch arrangement associated with each tap, each static switching element is in the form of at least one pair of silicon controlled rectifiers connected in reverse parallel so as to carry both directions of current. The S.C.R.'s can be used instead of mechanical diverter arrangements, known mechanical switches still being used for selecting taps (Fig. 2, not shown) or the static switching elements, one for each tap, may be controlled to have selecting and diverting functions, no mechanical selectors being used in this case. The arrangement of reverse-parallel pairs A, B and C, D &c. (Fig. 3), one pair for each tapping, eliminates the need for selecting taps in any particular order, as occurs when mechanical selector switches are used. Another arrangement, having various stages R1 . . . R4 (Fig. 4, not shown) employs seven pairs of rectifiers in the line to each tapping, in the most economical arrangement, but needs a complex control system for gating the rectifiers. Instead of single reverse-parallel pairs of rectifiers, several such pairs in series parallel or reverse parallel strings can be used (Figs. 5, 6, not shown).