GB328955A - Improvements in and relating to induction electricity meters - Google Patents

Abstract

328,955. Ferranti, Ltd., and Ferranti, S. Z. de. Nov. 5, 1928. Induction motor meters for single-phase threewire spstems have two driving elements each of which is individually complete and electrically associated solely with one side of the system, as shown in Fig. 8, the series coils 28 in the main 1 having their associated shunt winding 26 connected between the mains 1, 2, and the series coils 29 in the main 3 being associated with the shunt coil 27 connected between the mains 2, 3. By this arrangement, should the circuit of either main 1, 3 be opened by its fuse, the driving element on the other portion continues to function. In the construction shown in Fig. 4, the series coils 28, 29 are wound on core which are supported by, but laterally offset from, the poles of a C-shaped core 21, which are arranged at the opposite ends of a diameter of the rotor 4. The shunt coils 26, 27 are carried by a separate core limb 21<1> beneath the disc. Two separate pairs of brake-magnets are provided at opposite ends of a diameter, preferably at right angles to that containing the driving magnets. By this construction both driving and braking torques are balanced, as described in Specification 247,248. Preferably the spindle 32 is supported by a magnetic suspension device 33, 34 as described in Specification 322,995. In a modification the driving systems are magnetically separate. In a further modification, Fig. 12, a shunt magnet core similar to that described in Specification 247,248 is employed, the centre limb being unwound and the shunt coils 26, 27 arranged around the portions 2, 3 and 2<a>, 3<a>.