A simple approach to measure the surface resistivity of insulating materials

A simple approach for measuring high surface resistivity of insulating materials using standard laboratory equipments is proposed. The developed system consists of a DC power transformer, a concentric ring probe assembly and a digital multi-meter. The DC power transformer can provide either 500V or 250V DC signal. The probe assembly is constructed according to Danish Standard (DS/EN 1149-1:2006). The multi-meter (Agilent 3440 1A 6½) is used to measure the micro voltage over a known resistor which is serially connected with electrodes in the probe assembly. In order to obtain reliable measurements, two testing approaches, named on-off power sequence approach and alternating polarity sequence approach, are proposed and tested. The sample's surface resistivity is then calculated based on averaged measurements. The developed system and proposed methods have been extensively tested for different materials, source voltages, and serially connected resistors. The testing results showed that the developed system and methods can provide a reasonably accurate measurement of surface resistivity of insulating materials in a robust and economic manner.