GB525441A - Improvements in and relating to ferraris type of induction meters - Google Patents

Abstract

525,441. Supply meters. WIESENGRUND, M., and SZANTO, E. Feb. 21, 1939, No. 5737. [Class 37] An induction type meter having a two-pole current magnet 7 and a three-limbed voltage magnet 13 is constructed so that it may be overloaded to from three to four times its normal rated current without departing from permissible limits of accuracy. The threelimbed voltage magnet 13 is situated above the armature disc 12; the current magnet 7 being below the disc and nearer to the spindle than the magnet 13, so that the magnets 13, 7 are in staggered relation. The poles of the current core 7 are stepped or offset on the outside as shown in Fig. 3, so that the dimensions of the pole faces 14, 15 in the direction of movement of the disc 12 are small and the pole width d and the distance e between pole centres are also kept small. On one side of the current core is a magnetic shunt in the form of an angle iron, of which the flange 16 flat against the core forms the shunt, and the other flange has a central depression 19 so that the parts 20, 21 form extensions of the pole faces 14, 15. The shunt is secured to the core limbs by screws or rivets (not shown) with the interposition of a non- megnetic strip 17. The depression 19 serves to hold the counterpole 28, Fig. 5, of the voltage field, which is secured ot the outer limbs 22, 23 of the voltage magnet core by lugs 24, 25 engaging round the armature disc. Choke cores 30, 31 are located between each two adjacent limbs of the voltage core, gaps 32 being interposed between the choke cores 30, 31 and the outer limbs 22, 23.