Influence of Sample Surface Roughness on Charge Distribution Signal Obtained by Pulsed Electro-acoustic Method

Abstract

The pulsed electroacoustic (PEA) method is one of the useful electrical insulation evaluation technologies, which detects the space charge in the materials using the acoustic pressure wave. The space charge measurement was performed for an epoxy (EP) / Boron nitride (BN) insulating composite that is expected to be applied as a higher thermal conductive insulating material. The space charge profiles of EP/BN composite materials that cannot be explained by electromagnetic theory were observed. This controversial point appeared to be derived from the surface roughness of the sample, and there is a relationship between the surface roughness and the charge signal. The signal is adversely influenced by the surface roughness; therefore the sample which has smooth surface is required for the accurate space charge measurement of EP/BN composite.