Electric Field Modelling of Non-Ceramic High Voltage Insulators

Electric field calculations are not common practice in the design and development of non-ceramic insulators for high voltage transmission applications. This paper applies a three-dimensional (3D) electric field analysis program to calculate the field distribution at the live-end of 275kV and 330 kV non-ceramic insulators used in the Queensland transmission system. At these voltages, fields can be high enough to cause damage to the insulator sheath due to corona discharge, and grading devices need to be used to reduce the electric field to acceptable levels. Of particular interest to this research was the effect of end-fitting geometry and corona ring geometry on the electric field at the live-end of high voltage non-ceramic insulators. Three different non-ceramic insulator types were compared, and their fields are shown. Also a number of different ring geometries were compared. The effect of changing ring cross-sectional shape, diameter, and placement along the insulator are shown. All of these were found to influence the electric field at the live end.