The authors' theses (Ph. D.)--Johns Hopkins University, Brooks, 1926; Defandorf, 1927. / Cover title. Biographical sketches. Published also in U.S. Bureau of Standards. Bureau of Standards Journal of Research. Washington, 1928, v. 1, no. 4 and as U.S. Bureau of Standards. Research paper no. 21. Reprint from Bureau of Standards Journal of Research. October, 1928, under title "An experimental study of the corona voltmeter." Bibliography: p. 633.

Theses (Ph. D.)--Johns Hopkins University, 1926, 1927. / Caption title. Cover title: The electric strength of air between concentric cylinders: a new determination with the corona voltmeter, by Herbert Barton Brooks. Research on the Whitehead alternating current corona voltmeter with reference to the effect of humidity, by Francis Marion Defandorf. "Biographical sketches": on inside of back cover. Bibliography: p. 633.

The work presented in this thesis constitutes major developments in the use of the ultrahigh input impedance electric potential sensor (EPS). The EPS acts like a near perfect voltmeter, which detects the surface spatial potential distribution of a sample without making electrical contact to it (i.e. non-invasively). The EPS design is based on a commercial operational amplifier, to which electronic guarding and novel feedback techniques have been applied to increase dramatically the input impedance. Four areas of the EPS are discussed: Firstly, the exposed tip of the input-electrode defines the spatial resolution of the EPS. A new technique to develop coax input-electrodes with sharp, mechanically polished inner- conductors (tips) is examined. Secondly, the EPS is used to image carbon fibre composite samples with microscopic step size interval. The intention is to detect faults on the underside of these carbon fibre composite samples. This will provide a new approach for detecting unseen faults in carbon fibre composite applications as well as those based on other structurally important materials. Thirdly, an array of 8 ultra-high input impedance EPS has been developed. The aim is to explore the feasibility of using an EPS array, to reduce the length of time taken by a single EPS to image samples. Lastly, a high frequency version of the ultra-high input impedance EPS (up to lOOMHz) is studied. The objective of this high frequency EPS version is to measure noninvasively propagation time delays of pulses in real digital integrated circuits (ICs). This will provide a new technique to investigate high-speed digital systems, in particular when the ICs in these systems are operating close to their maximum frequency specification.

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A generating voltmeter capable of measuring one, two, or found million volts has been designed and constructed for use with the Virginia Polytechnical Institute electrostatic accelerator. The voltmeter is a grounded shutter type, the rectified output of which is measured by a vacuum tube voltmeter. The voltmeter was calibrated by known nuclear resonances of fluoride. The calibration showed the meter to be accurate to within five percent at half scale deflation on the one million volts range the less than plus or minus three percent on the two million volts range. / Master of Science

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / This research project investigates the design, modelling and application of an open-air capacitive voltage sensor assembly for the measurement of wideband High Voltage signals on three-phase transmission lines. The advantages and disadvantages of conventional methods used to measure these voltages are reviewed and the advantages of the open-air capacitive sensor are established. The main research objective of this project involves extending the application of previously developed single-phase capacitive sensor topologies to three-phase applications. A three-phase set of mobile, compact and relatively inexpensive capacitive voltage sensors for open-air application under overhead transmission lines are designed and constructed, including a data acquisition triggering system for the measurement of transient waveforms. Equivalent circuit models, using a Thévenin equivalent approach, are developed for the three-phase sensor topology and the associated three-phase transmission line configuration. A number of different methods for simplifying the associated Thévenin equivalent impedance and voltage equations are evaluated. The decoupling of the voltage waveforms measured by the individual sensors for a three-phase transmission line configuration is subsequently examined with the view to derive mathematical relationships for determining the phase conductor voltages from the measured sensor voltages. The performance of the sensor assembly is experimentally evaluated under laboratory conditions as well as field conditions. An outdoor HV test facility, representing a scaled three-phase flat transmission line structure, is developed for evaluation of the three-phase sensor topology in a controlled environment. The methodology for decoupling the phase voltages and reconstructing the phase conductor voltages from the voltages induced on the sensors is evaluated using measured data obtained with this HV test facility. It is shown that the three-phase capacitive voltage sensor topology as applied in the test facility delivers good results for the measurement of three-phase transient voltage waveforms.