GB976909A - Encapsulation of electrical power component - Google Patents

Abstract

976,909. Encapsulating electrical power components. EPOXYLITE CORPORATION. June 1, 1961 [June 3, 1960; Jan. 31, 1961], No. 19776/61. Heading B5A. [Also in Division H2] Windings which extend as annular protrusions from a magnetic core, such as stator or rotor windings in a dynamo-electric machine, are encapsulated in an insulating medium by arranging annular U-section channel members over the protruding portions of the windings to serve as moulds during the encapsulating process, the annular members being formed by bending suitable lengths of U-section channel of non-magnetic metallic foil sideways into circular form, at least one side wall of the channel having corrugations to provide strength combined with flexibility. Fig. 3 shows a section through an arcuate length of corrugated channel 1 seen from above in Fig. 1. Such channel 1 bent to annular form is arranged over the end windings for the stator of an electric motor. The outer edges 5 of the channels are bent outwardly and secured by adhesive to the stator core 12 ; the inner edges 6 are also secured to the stator core by an adhesive. In order to prevent contact between the channel 1 and the end windings 17 an insulating lining is provided to the channel or the windings are wrapped in an insulating fabric 18 such as glass cloth or paper. Preferably, further foil 21, 22 is bonded to the outer and inner surfaces of the stator 56 and the stator is effectively totally enclosed. Leads are led out at 19 and a further aperture is provided at 20 through which the liquid encapsulating medium, such as a thermosetting or thermoplastic resin, preferably an epoxy resin, is introduced before curing or setting. A neoprene bore expander 23 is introduced down the centre of the stator to reinforce the inner surface of the channel 1 and the foil 22 during impregnation. The foils 1, 21, 22 may be removed after encapsulation or may be left to provide a " canned " stator. Alternatively, if the foil 21, 22 is not used during encapsulation it may be added later. Alternative forms of channel which are corrugated on inner or outer surfaces only may be used.