GB506370A - Improvements in and relating to electric induction meters - Google Patents

Abstract

506,370. Supply meters. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 7, 1938, No. 26161. Convention date, Sept. 9, 1937. [Class 37] In order to make a, multiple-element or polyphase meter comparable in size with a single-element meter, the driving magnets are arranged around the peripheral portion of the armature disc and the brake magnets are arranged nearer the shaft. As shown in Fig. 1, a three-phase induction meter has the three driving-elements 11, 12, 13 arranged around the periphery of the disc 10, the central portion of which is acted on by brake magnets 14. The aluminium disc 10 may be made of several disc layers stacked one above the other, each layer having segments insulated from each other by slits 19 and the segments in different layers overlapping. Currents induced in different disc segments are thereby prevented from spreading so as to cause interference between different driving elements. The central portion of the armature is provided with auxiliary copper discs 24, 25, Fig. 2, to increase the conductivity. Four permanent magnets 14 are arranged above the disc and four below it so that opposite poles face one another above and below the disc. They are secured to magnetic supporting plates 22, 23 at the ends remote from the armature. Two magnets on each side of the armature have north poles facing the disc, the other two having south poles facing the disc. The plates 22, 23 may be extended outwards to support the driving elements. To adjust the damping, an iron ring 27 forming a magnetic shunt surrounds each set of four magnets and is supported by bolts 28 and guide rods 26. The lower step bearing 33 is screwed into the plate 23, the upper bearing being carried by a bridge-piece attached to the upper plate 22. Specification 424,746, [Goup II], is referred to.