GB312217A - Improvements in or relating to dynamo-electric machines - Google Patents

Abstract

312,217. Kuyser, J. A., and Associated Electrical Industries, Ltd. Feb. 22. 1928. Coils and conductors; insulation; cores; windings.- An alternating-current machine has a number of complete windings superposed in layers in the same slots with insulations of increasing strength from the innermost to the outermost winding, the windings being connected in series so that the potential of the innermost and outermost windings are respectively nearest to and furthest from that of the core. In the form shown, three windings 3, 4, 5 are used with an approximately common conductor section and insulation thicknesses increasing from the innermost 3, which has the lowest potential with regard to the core, to the outermost 5. The end connectors 6 of the low potential winding are kept nearest to the core end-plate 2. The winding 3 is first wound as a 3-phase star system and it is insulated at the bottom of the slots so as to withstand its own voltage to correspond with the requisite factor of safety. The second winding 4 is then wound' as an open 3-phase winding over and in series with the winding 3 and it is insulated to withstand the sum of the voltages in both windings with the required factor of safety. The third winding 5 is similarly wound and insulated over and in series with the winding 4. To enable insulation of different thicknesses to be used in parallel sided slots, the conductor sections in the windings may differ, as in Fig. 2, or, alternatively, the slots may be stepped, as in Fig. 3, with their widest parts at the bottom.