GB190513696A - Improvements in Alternating Current Electricity Meters. - Google Patents

Abstract

13,696. Hamilton, W., and Ferranti, Ltd. July 3. Energy meters of the inductionmotor type. The pole pieces of the shunt magnet are made very long, extending further from the coil than in previous arrangements such as that described in Specification No. 18,766, A.D. 1902, and the coil itself is made adjustable along the core, for the purpose of obtaining the requisite phase displacement and compensation for friction. The shunt and series magnets are separately arranged to give a small torque, both in the same direction, to compensate for the braking effects of the magnet poles as well as for pivot and train friction. In the meter shown in section in Fig. 2, the pole-pieces i are extended downwards from the core f and underneath the disk, the polar surfaces being arranged opposite the gaps between the three limbs of the series magnet d. This magnet is situated a little in advance of the symmetrical position as regards the direction of motion of the disk armature, and the shunt coil h is displaced in the same direction by means of set-screws o. The meter may be regulated for different frequencies by means of a resistance k in the shunt circuit, or by making the coil h in two separate parts, and either varying the distance between them, or placing iron washers between them ; or the coils may be shaped in accordance with requirements, and the pole-pieces of the shunt magnet may be partially laminated. An auxiliary starting-coil may be wound on one of the pole-pieces or over the shunt coil, and may be adjustable thereon. Shunt magnets of the form shown in Figs. 5 and 6 may be used. The invention is applicable to polyphase meters in the manner described in the above-mentioned Specification.