Influence of the insulator geometry on the streamer propagation characteristics in polymeric insulators under positive polarity lightning impulse voltages

Abstract

Polymer composite insulators acquire the position of their counterpart ceramic and glass insulators in high voltage overhead transmission systems due to their remarkable pollution performance. They have different potential and electric field distributions compared to that of ceramic insulators and the absence of intermediate pin and cap metal fittings makes them compact in size by reducing the distance between energised and grounded ends. This study presents a simulation-based approach to compute the streamer propagation characteristics in polymer suspension insulators under positive polarity lightning impulse voltages. The streamer inception, propagation, and sustenance criteria are evaluated using finite element method-based electric field computations. The significance of insulator geometries on streamer inception and propagation phenomena is well established. The insulator geometries such as weather sheds, location of the first shed, and shed radius have shown a strong influence on streamer inception and propagation path, which govern the flashover characteristics of the insulator. The lightning impulse flashover voltages of different insulators were determined experimentally to validate the computed results. A good agreement is found between simulation and experimental results.