GB1013927A - Improvements in electromagnets - Google Patents

Abstract

1,013,927. Induction meters. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. April 3,1963 [April 25,1962], No. 15818/62. Heading G1Q. In an A.C. induction meter such as a wattmeter or, as shown in Figs. 1, 3, a watt-hour-meter, the U-shaped laminated core 11 of the current magnet is provided with two polepieces 15, each comprising a flat part ] 5A which is separated from the core 11 by a non-magnetic plate 17, e.g. of brass, and a part 15B, parallel to part 15A but offset therefrom in the direction of the base of the core 11, and an overload shunt 21 bridges the parts 15B being separated therefrom by a brass plate 25 and secured by rivets 23, 27; the exposed faces of shunt 21 and parts 15A are substantially coplanar although the face of shunt 21 is preferably slightly proud of parts 15A In a modification, Fig. 4 the offset parts 15B of the polepieces are located between the limbs of the core 11, the shunt 31 and non-magnetic plate 35 being riveted to a second nonmagnetic plate 37 below the polepieces; the shunt 31 has a central aperture to facilitate its saturation.