GB648036A - Improvements relating to electricity meters - Google Patents

Abstract

648,036. Energy and power meters. MEASUREMENT, Ltd., HEWLETT, S. J., and BIBBEET, J. A. Nov. 10, 1948, No. 29195. [Class 37] In an A.C. power or energy meter, an induction disc a is rotatable by opposed torques exerted by driving elements c, b which are respectively energized by currents derived from the line current in one phase of the system and from the output of a valve f amplifying the output of an induction regulator coil d rotated by disc a in an electromagnetic field e energized by one phase voltage. The voltage coil i of a wattmeter or watthourmeter is supplied from the same phase voltage, and the current coil h, is connected in series with the driving element b and the amplifier output. The disc a assumes a position wherein the driving torques balance, the amplified output from coil d in phase with the line voltage is proportional to the line current, and the meter indicates apparent power irrespective of the phase difference between line voltage and current. The induction regulator may be replaced by a variable capacitor in series with a larger fixed capacitor. or the induction disc may operate follow-up contacts and a servometer to rotate the regulator coil, which may energize the driving element and the meter current coil directly without amplification. For unbalanced 3- phase measurements, the phase-correcting device may be duplicated in conjunction with a 2-element wattmeter. The Provisional Specification refers to the use of a magnetic amplifier, and direct driving of the regulator by the induction disc through reduction gearing.