High Voltage Stress and Equipotenial Mapping

Voltage stresses on power systems arise from various over voltages. These are either external voltages which are associated with lightning discharges and are not dependent on the voltage of the system, or internal over voltages which are generated by changes in the operating conditions of the system such as switching operations, faults on the system or fluctuations in the load or generation. Electric fields can be computed using various methods with different precision. However for insulation of electrical equipment a more accurate electric field prediction is required. With the advent of computing power and numerical techniques in recent years, it has become practical to compute the electric fields quite accurately. Such numerical techniques enable the designer to solve problems that are difficult, and the use of analytical approach with many empirical factors is impossible. Pollution flashover is one of the main problems that endanger the reliability of an electric power system. Flashover measurements around and over the surfaces of samples of clean and polluted insulators were made with the aim of validating the results obtained from simulation.