GB1050521A - - Google Patents

Abstract

1,050,521. Dynamo-electric machines. ENGLISH ELECTRIC CO. Ltd. May 30, 1963 [March 8, 1962], No. 8888/62. Heading H2A. [Also in Division H1] The stator and rotor windings of a dynamo-electric machine are cooled substantially below the ambient temperature to reduce their resistance. The cooling may be enough to produce superconductivity. The machine may be of planar or cylindrical air-gap type. In the planar type shown, flat winding of semicircular sector shape (Fig. 2, not shown) is mounted in fibre-glass stator and rotor discs 15A-15M and 14A-14M respectively. The hollow rotor shaft 10 is of the same material. For superconductive working, the machine casing 18 is sufficiently cooled by helium to freeze the air and so produce a vacuum in the casing. In addition, the stator and rotor windings are cooled by helium in ducts. Air leaking into the machine is frozen on fingers 27. The flux circuit is completed by magnetic blocks 17 or flux diverters of superconductive material. The rotor may be short-circuited by a superconductive link which may, however, be rendered resistive by a transition flux from a coil in the hollow shaft. The rotor may be of stainless steel. A cylindrical form is also described (Figs. 3, 4, not shown). The diverter may be of very pure aluminium cooled to 20‹ K. but this may be replaced by a superconducting film or by conventional laminations outside the machine. Stator and rotor windings may be of pure niobium, niobium tin alloys, vanadium gallium alloys, niobium zirconium alloys, or sintered niobium and tin powder in a thin tube of niobium. The interior of the machine is at 4-20‹ K.