GB1102344A - Improvements in or relating to electric transformer apparatus - Google Patents

Abstract

1,102,344. Transformers. BRENTFORD ELECTRIC Ltd., and C. B. HENMAN. 24 Aug., 1964 [29 Aug., 1963], No. 34284/63. Heading HIT. [Also in Division H2] The flux leakage and copper losses of an autotransformer, whose winding is tapped by slidiing brushes or rollers, are reduced by providing one or more compensating windings each of which is wound adjacent to but insulated from one part of the main winding and is connected in parallel with another part of the winding having the same number of turns as the compensating winding. Fig. 1 is typical of the two basic arrangements described and has a compensating winding 18 wound on the same former as the main winding 11 and underneath the part 21 thereof, the remaining part 20 being in parallel with the winding 18. In Fig. 4 the roller 17 only moves over a portion 40 of the main winding 11, the remaining portion 41 being wound underneath that part of the winding portion 40 which is connected in parallel with the compensating winding 18. In this arrangement the windings 18, 41 and the two halves of winding 40 have the same number of turns. The winding shown in Fig. 6 is divided into four equal sections 43, 44, 45, 46 and has two compensating windings 18a, 18b, respectively wound underneath sections 45, 44 and parallel connected to sections 43, 46. This arrangement may be modified by using two rollers maintained equi-distant from the mid-point of the winding, Figs. 8, 9 and 12 (not shown). In Fig. 10 the winding 11 is divided into seven sections 61 ... 67 of which 61 ... 63, 65 ... 67 have the same number of turns which is half as many as the section 64. Four compensating windings 18a, 18b, 18c, 18d are provided respectively wound underneath sections 65, 63, 66, 62 and parallelconnected to sections 61, 67, 64, the windings 18c, 18d forming a series circuit across the section 64. The compensating winding may comprise a number of tubular turns of copper or aluminium sheet wrapped around the core, each turn extending continuously along the length of the compensating winding. The arrangements disclosed are stated to improve the linearity of the variation of electrical output with the position of the roller 17 along the winding.