GB528830A - Improvements in or relating to induction type electricity integrating meters - Google Patents

Abstract

528,830. Supply meters. FERRANTI. Ltd., PRINCE, J., and WHITEHEAD, M, May 16, 1939, No. 14553. [Class 37] For improving the registration curve of an induction meter a plurality of salient portions of the stampings forming part of either the shunt or series electromagnet protrude into an air gap forming part of the series flux path and become saturated at differing values of the total series flux. Alternatively pieces of ferromagnetic material may be arranged parallel to each other in the air gap. As shown in Fig. 2 an E-shaped shunt magnet 1 is arranged above a U-shaped series magnet 2, the meter disc 12 rotating in the gap between them. The core of the series magnet 2 includes two sets of stampings 3, 4 of differing lengths but both longer than the remaining stampings 5. The longer stampings 3, 4 are of high permeability material and saturate at differing values of the total flux: Alternatively the shunt magnet may have some of its stampings with either the middle or the outer limbs longer than the others. In another modification, Fig. 7, the series magnet 2 is built up of stampings which are stepped to form salient portions 10, 11. Alternatively the shunt magnet may have one or more limbs of some or all of its stampings similarly stepped. In another construction, Fig. 5, pieces 8 of high permeability metal are disposed in each of the air gaps between the two magnets 1, 2, individual pieces in each gap becoming saturated at different values of total series flux. They are held in position by a brass bracket 9 attached to the shunt magnet core.