Measurements and calculations of surface charge on the cone-type insulator

The solid insulators in gas insulated equipment are of great important to the electrical insulation reliability of such equipment. It was confirmed that surface charge accumulation on the insulator is the most important matter that can degrade the overall performance of these insulation systems. In order to study the phenomenon of surface charge accumulation on cone-type insulators, which are most commonly used in gas insulated systems, a set of device for surface charge measurement is designed based on the electrostatic probe technique. The Trek Model 347 voltmeter and a vibrating probe are utilized to obtain the surface voltages of the insulator. Moreover, an improved numerical computing method is introduced to calculate the surface charge. The measured results show that this technique can be used to measure the spatial distribution of surface charge on the cone-type insulator with satisfactory accuracy and resolution.