GB853611A - Improvements in and relating to dynamo-electric machines - Google Patents

Abstract

853,611. Dynamo - electric machines. ENGLISH ELECTRIC CO. Ltd. Nov. 9, 1956 [Nov. 5, 1955], No. 32625/55. Class 35 To permit relative movement and thereby avoid " copper shortening " resulting from different thermal expansions of a coil and its supporting core member in a dynamo-electric machine, the parts are separated by means comprising or including a solid electricallyinsulating material which exhibits a low coefficient of friction relatively to normal insulating materials such as glass-fabric, mica or asbestos. The low coefficient material is polytetrafluorethylene which is impregnated in or coated on one or both sides of various materials. Fig. 1 shows a turbo-alternator rotor solid cylindrical ferromagnetic core 12 in whose axial slots 11 are radially stacked copper winding conductors 10 separated from each other and from a damping winding 16 and slot wedges 13 by strips 18 and a member 17 respectively, both of P.T.F.E. impregnated asbestos. A slot lining trough 15 may be of either similar material or a conventional insulating material. In other similar embodiments, not shown, the member 17 is omitted but the damping winding is of P.T.F.E. impregnated copper, or in the case of a slotted stator the winding coil sides are wrapped externally with P.T.F.E. impregnated cloth. In Fig. 2 a layer 22 of P.T.F.E. impregnated asbestos is disposed between the outermost end winding conductor 20a of a rotor and an annular end member 21 which supports the end windings against centrifugal force. In Fig. 3 a salient pole rotor has winding interturn insulation 33 and an end insulating washer 32, all of P.T.F.E. impregnated asbestos, and in a modification the end washer may be of P.T.F.E. impregnated sintered steel.