GB1329867A - Polyphase on-load tap-changers for regulating transformers - Google Patents

Abstract

1329867 Transformers SMIT NIJMEGEN ELECTROTECHNISCHE FABRIEKEN NV 16 Oct 1970 [16 Oct 1969] 49350/70 Heading H1T Main windings 1 of a three phase transformer are connected to the star point 17 through a regulating winding 2 and a circular three phase diverting switch 7. Each regulating winding 2 has two series of tappings 3 and fixed contacts 4 connectible through bridging contacts 5 to fixed contact strips 6. The regulating range may be doubled using a change-over selector (18, Fig. 2, not shown) for buck and boost regulation, and increased further using another change-over selector 35 (Fig. 5) to add coarse voltage regulation to the fine regulation windings 2. The diverting switch 7 has a circular set of six fixed contacts 8-13, and a set of movable contacts comprising three main contacts 15 and six auxiliary contacts 16, the latter connected to the star point 17 through transition resistances 14. An asymmetric variant of the diverter switch with only three auxiliary contacts (34, Fig. 4, not shown) is described, and Fig. 5 shows a diverter switch 39 with "double interruption" provided with a set of twelve fixed contacts 40-51 co-operating with three sets of movable contacts, each comprising two main contacts 52 connected in series and two pairs of auxiliary contacts 54 connected in series through transition resistances 53. The two resistances may be replaced by a single resistance, and transition resistances may also be arranged to be stationary externally of the switch (Figs. 3, 4, 7, not shown). In principle the number of fixed contacts in the diverter switch is an integral multiple of the number of phases, as is the number of movable main contacts and number of auxiliary contacts.