NDLI: A novel circuit for electronic power-factor meters and wattmeters, and a novel division device

Content Provider	IEEE Xplore Digital Library
Author	Ahmed, M. Abdel-Halim
Copyright Year	2012
Abstract	Three novel electronic measuring instruments are presented, which may be used to measure power, power factor (pf), voltage, current, or impedance. They use two tubes, operated as cathode followers, in a push-pull fashion, so that the inherent property of a wide-range linear characteristic is employed to advantage. The new principle underlying the operation of the tubes involves the commutation of their currents in alternate half-cycles by means of a square-wave generator. The resulting average plate current is a direct measure of the product I cos ¿. A rectifier gives a direct current proportional to the alternating voltage, and an electrodynamic instrument multiplies the two direct currents, thus giving a direct reading of the power. For the direct reading of pf, two direct currents are obtained, one being proportional to the product V cos ¿ and the other proportional to V. Their quotient is a direct measure of cos ¿. The division is effected by means of a twin logarithmic d-c instrument having a movable scale. The instruments are characterized by their simplicity, reliability, high accuracy, and stability. They have exceptionally good features and predictable performance over a frequency range extending from the lowest power frequencies to a predicted value of about 30 megacycles (mc) when using high-frequency tubes; the main limiting factor being the stray capacities across the output of the square-wave generator. There are, however, some other factors which tend to lower this operating limit, and 10 mc is considered a reasonable higher limit.
Starting Page	194
Ending Page	204
Page Count	11
File Size	2867124
File Format	PDF
ISSN	00972452
Volume Number	74
Issue Number	2
Language	English
Publisher	American Institute of Electrical Engineers
Publisher Date	1955-05-01
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Electron tubes Instruments Generators Harmonic analysis Current measurement Cathodes Impedance
Content Type	Text
Resource Type	Article

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