Geometrical effects on hold-off voltage in polystyrene insulator

Research has shown that there are several methods by which higher flashover and breakdown voltages of electrical insulating materials can be achieved. While breakdown voltage is predominantly affected by the insulation bulk material, many factors contribute to the flashover performance of an insulator. Such includes material composition, operating environment, interface between current carrying conductor and the insulating medium, as well as micro scale defects on the surface of the insulator. Furthermore, the physical geometry of the insulating material has been identified as a critical factor that also affects the flashover performance. This research focuses on how geometric designs of polystyrene insulator samples affect the surface flashover characteristics and holdoff voltage in vacuum. Studies of similar polymers in literature have shown that a reduction in the electric field strength at the cathode triple junction reduces the primary electron emission at the cathode under high voltage stresses. Four groups of polystyrene shapes were studied and the analyses of the effects of the geometries are presented along with results from finite element analysis studies.