GB555956A - Improvements relating to induction type electricity meters - Google Patents

Abstract

555,956. Supply meters. FERRANTI, Ltd., and PRINCE, J. May 13, 1942, No. 6481. [Class 37] An induction type meter has a braking system which includes a permanent magnet and two projections forming part of the frame of magnetic material the permanent magnet and projections being so arranged that the rotor can be removed without disturbing the braking svstem. In the construction shown in plan in Fig. 2 and side elevation in Fig. 3, the main frame 1 is of cast iron and carries the driving magnets 2, 3 and bearing 4, 5 for the rotor pivots. The U-shaped braking magnet 8 is of alnico or other steel having a coercive force greater than about 250 oersted. It is mounted on a brass spacing block 9 and is held in position by a brass strap 91 so that the faces of both poles lie in a plane parallel to and below that of the disc 6. Above each pole of the magnet 8 is a cast projection 11 from the main frame 1, the crosssection of each projection being sufficient to take the braking flux. These projections have surfaces 12 in a plane parallel to and above the plane of the disc and are disposed one on each side of the rotor spindle. Withdrawable bearings for the rotor pivots are locked in position by screws 13, 14. After withdrawing the bearings the rotor may be removed without disturbing either the driving or braking systems. According to the Provisional Specification four projections may be provided, two above and two below the disc, serving as polepieces for the magnet, which is arranged to bridge them. Specification 455,513 is referred to.