GB1526081A - Corona suppression in high voltage windings of dynamoelectric machines - Google Patents

Abstract

1526081 Insulating conductors of high voltage machines WESTINGHOUSE ELECTRIC CORP 20 Oct 1975 [29 Oct 1974] 42908/75 Heading H2A To reduce voltage stress and effect corona suppression in the stator winding of a high voltage dynamo-electric machine in which the winding conductor 22 cross-section has linear parts meeting at a curved edge, one or more electrically conductive layers 26 are disposed within the thickness of the insulation 24, 28 around the conductor 22, with the or each layer 26 being substantially coaxial relative to the conductor and located such that:- where the curved edge of the conductor has a radius r, the insulation has a radial thickness T in the curved region surrounding said edge, n is the number of layers 26, and x l is the spacing of the ith layer 26 from said curved edge of the conductor 22. The stator (10), Fig. 1 (not shown) is laminated and has mica, asbestos or fibreglass wedges (14) retaining the conductors 20 slots (12), micanite separators (16) being located between adjacent conductors in each slot. The insulation 24, 28 may be formed by multiple layers of tape, e.g. mica splitting tape or mica paper and the layers 26 may be metal foil or conducting impregnatable tape to allow vacuum impregnation of the composite insulation 24, 26, 28. The conducting layers 26 extend axially out from the ends of the slots (12) as does an outer semiconductor layer 29, e.g. silicon carbide, on the insulation, layer 26 extending at least as far from the slots as layer 29, to provide axial voltage grading in addition to the radial grading produced by layers 26.