Partial Discharge Patterns in Conducting and Non-Conducting Electrical Trees

Previous observations on electrical tree growth in epoxy resins has shown that different types of tree growth structure, electrically conducting and non-conducting, can occur dependent on the state, glassy or flexible, of the epoxy resin. In this current study, the partial discharge characteristics were characterized experimentally at a temperature of 20 degrees C within two different epoxy resins systems having glass transition temperatures of 0 degrees C and 50 degrees C. The partial discharge activity (determined from apparent charge measurements) was characterized in terms of phi similar to q similar to n patterns using statistical tools. The aim was to compare the apparent charge measurements obtained from conducting and non-conducting electrical tree structures with computer simulations of the partial discharge activity in both conducting and non-conducting electrical trees. The results show that there is a significant relationship between the local extent of the partial discharge phenomena, as determined by the conductivity of the tree channels, and the apparent charge, as shown by the experimental and simulated partial discharge patterns. The implications of this work for partial discharge detection as well as for condition monitoring in real insulating systems are discussed.