Transient Electric Field Analysis for Polluted Composite Insulators Under HVDC Stress

The present investigation highlights simulation study performed considering the temporal transformation of the electric field from capacitive to resistive. The effect of uniform pollution, single dry-band, multiple dry-bands and non-uniform pollution are studied in detail. The simulation results indicate the effect of surface current can literally decrease the voltage withstand capability of the insulator. The simulations are carried out under time domain so that the simplicity and the physical integrity of the problem is retained. Experimental investigations are conducted to verify the obtained theoretical results. Investigations show that there is substantial decrement of scintillation inception voltage with time, further experimental observations are explained based on the theoretical results that have been derived. Based on the theoretical and experimental observations, it is thought that proper insulation design and optimal creepage should be provided under DC, as field distribution can change over a period with increasing surface conductivity.