Abstract
IN his chairman's address to the Meter and Instrument Section of the Institution of Electrical Engineers (J. Inst. Elec. Eng., 89, Pt. 1, No. 13, January, 1942), W. Phillips surveys the design and performance of electrical instruments. Development since the 1890's has been twofold: first in widening the limits of measurement, and secondly in accuracy. Switchboard moving-coil instruments are now available to give full-scale deflection for 10 µ amp. or less, and ammeters having a range of 30,000 amp. are in use. In voltage, the range is from a few micro-volts., with apparently no upper limit, the sensitivity of D. C. moving-coil instruments now being limited only by the non-magnetic quality of the moving system. The standardization of frequency at 50 c./s., and its close regulation by supply undertakings, has fostered the design and use of testing apparatus for the measurement of power factor, peak factor, and current ; and also of voltage testing sets and similar apparatus for use at fixed frequency. The Electricity Supply (Meters) Act created an immediate demand for standard and sub-standard instruments of all types, large sums being expended by supply authorities in equipping meter-testing stations. Great improvements in wattmeter performance have been made, particularly in the reduction of self-heating error and D. C./A. C. change-over error.
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Electrical Instruments. Nature 149, 408 (1942). https://doi.org/10.1038/149408b0
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DOI: https://doi.org/10.1038/149408b0