An experimental study of the corona voltmeter

Abstract

Whitehead's corona voltmeter (rating 140 kv effective voltage) was modified in order to improve control of pressure, temperature, and humidity. A new and highly accurate method of determining the 60-cycle crest voltage was uscd in studying this device, within a pressure range of three atmospheres and a temperature range of 15° to 45° C. Twelve corona rods of diameters from 0.12 to 1.1 cm were used in this investigation . One outer cylinder of 25 cm diameter was used.Increase in humidity was found to lower the corona voltage for a dusty or otherwise soiled rod, although it generally caused an increa,se for carefully cleaned rods.Maintenance and duplication of a given condition of the surface of the corona r od appear to be the factors that limit the repeatability in the present type of instrument. Further invest igations of the effect of surface conditions would be of interest.Our experimental results have led us to propose the following modified law of cor ona formation in dry air between concentric cylinders : g=A/j+B..j/jjr-Cjrfor which our experiments gave A=27.95 B=I1.18 C=0.365