Porcelain insulators are extensively used in overhead high voltage transmission lines. Uninterrupted reliable operation of a power system depends on a satisfactory performance of insulators under different environmental conditions. This paper presents the results of a study of the transient and power frequency voltage distribution along a 230kV cap and pin type porcelain insulator string in both clean and pollution conditions. Finite element method based software, MAXWELL v.14, is used for some 3-D simulations to investigate the effects of tower, conductor and four different types of corona ring on voltage distribution along the insulator string. Also, by choosing the optimal corona ring type, the equivalent circuit for a suspended insulator string in pollution condition is represented. The voltage distribution along HV insulator string for different severities of surface pollution is calculated by ATP-EMTP software, by using the optimal corona ring and presented equivalent circuit. The capacitive-resistive voltage distribution along the polluted string under both AC and transient voltages are also calculated to show the disadvantages of pollution on performance of the string.

Full text: IJEIR_793_Final.pdf