Analytical studies of HV insulators in Saudi Arabia-theoretical aspects

Digital computer studies of long, contaminated insulator strings are performed using linear, lumped circuit models. The voltage distribution, currents, phase angle and wattage for each unit on the string are evaluated for practical combinations of uniform and nonuniform distribution of contamination. The variations in performance as a function of stray capacitance and shielding fields are discussed, taking into account a wide range of the pollution index, tower designs varying at different areas, and the environmental conditions of Saudi Arabia, the physics of the evaluation of the voltage distribution and phase angle variations along the insulator string as the surface is changed from clean, to dirty, to contaminated, to polluted are evaluated. The iteration technique is used to explore the effect of nonlinearities in resistance as a function of temperature variations and current limits. Changes in surface resistance due to liberated energy are considered. Studies are performed on a per-unit basis to simplify the adoption of the results to insulator strings used under various conditions