Peak Voltage Measurements Using Standard Sphere Gap Method

Constantin Ungureanu,Lăcrămioara Mihaela Nemțoi

doi:10.1155/2014/980913

Abstract

The paper presents a measurement system of peak value of high voltage (H.V.) using 150 mm diameter sphere gap, disposed in vertical position. Experimental breakdown results have been compared with standard values at atmospheric reference conditions STC (20°C, 101.3 kPa, or 760 mmHg). The main experimental and theoretical characteristics are presented.

Highlights

Choosing the most suitable method for measuring high voltage depends on the measured voltage value, on the available measuring devices, and on whether the need is to measure the peak or the effective value
The standard peak values of breakdown voltage, in air, for symmetrical spheres of 150 mm in diameter, have been corrected to the standard temperature and pressure according to relations (1) and (2)
It has been shown that the breakdown voltage increases with the gap spacing almost linearly

Summary

Introduction

Choosing the most suitable method for measuring high voltage depends on the measured voltage value, on the available measuring devices, and on whether the need is to measure the peak or the effective value. It is known that spark gap spheres measure the peak AC voltage with a precision of ±3%. The breakdown voltage depends on the distance between the spheres, on the spheres diameter, and on the type of voltage: direct, alternating, or impulse. The breakdown voltage is a nonlinear function of the gap distance which is due to the increasing field inhomogeneity [1]. Sphere gaps can be arranged vertically, with the lower sphere grounded, or horizontally. In both cases, one must take into account the parameters A and B which define the field distribution between the two spheres that are closest to each other. For 150 mm sphere diameter, the minimum value of A is 6D and the maximum value is 8D (where D is the sphere diameter) while the minimum value for parameter B minimum is 12S (where S is the spacing) [2, 3]

Methods

Results

Conclusion