Effect of Charged Sphere Size on Electrostatic Discharge Generated while Approaching a Stationary Object

Abstract

This study experimentally clarified that changing the size of a charged object affects the characteristics of the electrostatic discharge (ESD) that occurs when a charged object moves toward a stationary, grounded object. The spark lengths and discharge currents were measured as charged, metallic, spherical electrodes of different diameters approached a stationary grounded object at different speeds. The charge voltages of a DC high-voltage power supply were +4.0kV and +6.5kV. According to the results, the average spark length tended to shorten with the speed of the spherical electrodes. The change in the average spark length with the speed of the 5.0-mm-diameter spherical electrode was faster than that for the 15.9mm-diameter spherical electrode. The average peak value of the first peak of the discharge current for the 5.0-mm-diameter spherical electrode was greater than the average value for the 15.9-mm-diameter spherical electrode when the approach speed was greater than 5mm/s for both spherical electrodes. The peak value, rise time, and rising speed of the first peak of the discharge current also correlate with the spark length, and the correlation can be explained qualitatively by the empirical equation deduced from the resistance formula proposed by Rompe and Weizel .