GB837546A - Improvements in and relating to dynamo-electric machines - Google Patents

Abstract

837,546. Dynamo-electric machines. PARSONS & CO. Ltd., C. A. Sept. 7, 1956 [Sept. 26, 1955], No. 27379/55. Class 35. A dynamo - electric machine, e.g. a large turbo - alternator, has stator windings formed partly or wholly by electrical conductors 1 accommodated in a cylinder 2 located in the air gap 3 between the stator and rotor cores 4, 5 of the machine, the conductors 1 being insulated from each other and the insulation being contacted by a high electrical resistance electrically conducting sheath connected at a plurality of points either to earth or to the winding neutral point. The conductors are of circular, rectangular or square cross-section and are subdivided into strips twisted or transposed to minimize eddy currents. As shown in Figs. 2c and 3b, they may have a central duct 7<SP>1</SP> through which is passed a cooling liquid or gas, e.g. hydrogen, an outer insulation 8<SP>1</SP> formed by a micanite tube or a silicone compound or paper, and the highresistance sheath 10 which may be a metal tape or wire or a graphite coating. The cylinder 2 extends the full length or as shown in Fig. 1, part of the length of the conductors 1 and may comprise a casting resin or concrete; in other forms it may comprise segments bolted together or two concentric cylinders of phenol - formaldehyde resin, Fullerboard, or micanite between which is cast an epoxy resin supporting the conductors. The cylinder 18, Fig. 6, may embody packs of grain orientated magnetic laminations 17 forming teeth between the conductors, and to prevent it in rotating in the stator has either integral projections 16, Fig. 2c, or recesses or locating means at one or both ends. In another embodiment, not shown, bore conductors are embedded in an electrically insulating cylinder 2 bounded at its inner or outer periphery, or both by the high-resistance sheath. Liquid coolant headers may be cast integrally with the cylinder.