| 摘要 |
<p>990,418. Transformers. GENERAL ELECTRIC CO. Aug. 18, 1961 [Aug. 22, 1960], No. 29889/61. Heading H1T. An electrically conducting shield structure 20 (Fig. 3) is provided in an electrical apparatus having a core and one or more foil windings to reduce current concentrations at the edges of the windings, caused by radial flux leakage, by establishing a magnetic field adjacent to the surface of each winding in opposition to the radial component of flux passing through the winding. In Fig. 1 a three-phase transformer, comprising a core 11 with yokes 15 and legs 12 carrying spirally wound aluminium or copper foil H.T. windings 13 and L.T. winnings 14, has shields 20 between the L.T. winding and core and surrounding the H.T. winding, the ends 25 of the shields defining an air gap to prevent short-circuiting currents in the shield. The lower shields and the windings are supported by insulating blocks 30 and the upper shields by insulating spacers 31. Conventional spacers (not shown) may separate the shields from the windings allowing the passage of cooling fluid. The surrounding shields may be electrically connected to the H.T. winding to reduce the voltage gradient at the edge portions of the coil. The flux emanating from the shields is created by induced currents therein, or alternatively by an alternating current applied directly to the shield. Fig. 4 (not shown) illustrates the flux distribution in the foil windings and due to the induced currents in the shields.</p> |
