Dynamic measurement of surface charge

This paper describes the development of a system capable of monitoring the dynamic movement of surface charge on insulating materials. High electrical stress can be generated at the edges of an interface between a conductor and solid insulation by the existence of a non-uniform field. This may cause local sparking and corona along the surface of the insulation. The presence of surface discharge activity is a significant problem for organic insulators. Any discharge can cause a slow deterioration of the insulator surface in the long term through three mechanisms: Slow erosion by ionic bombardment of ions in the sparks, chemical degradation and carbonisation of the surface material. Conducting deposits are formed on the surface and this will influence the electrical characteristics of the insulator. The development of a suitable method to monitor surface discharge behaviour of high voltage (hv) insulating materials is therefore of particular interest.