Analysis and comparison of streamer discharge characteristics in equipotential live-line work gap and its simplified gaps under positive switching impulse

Equipotential live-line work (EPLW) is crucial for uninterrupted operation and maintenance of extra-high voltage (EHV) and ultra-high voltage (UHV) transmission lines. Determining the minimum approach distance (MAD) for EHV and UHV systems needs a thorough grasp of EPLW gap discharge mechanisms and characteristics for worker protection. Therefore, we conduct positive switching impulse discharge experiments on EPLW gap and its simplified gaps at a gap distance of 3 m, study the discharge development process and streamer inception characteristics of two gaps, and perform comparative analysis. The experimental results show that sim-worker's feet-test tower gap and the bundle conductor + rod-plane gaps (rod electrode with radii of 2.5 cm and 5 cm) occur multiple streamer inception. The bundle conductor + rod electrode with a radius of 8 cm only has one streamer inception. The average inception voltage, inception time delay and its dispersion of bundle conductor + rod electrode will all rise with the size of the electrode. Compared to the bundle conductor + rod electrodes with radii of 2.5 cm and 8 cm, the average streamer inception time delay and inception voltage of sim-worker's feet are only 3.6 % and 5.1 % subtly higher than those of the bundle conductor + rod electrode with a radius of 5 cm, and a high degree of similarity is exhibited in their probability distribution trends of streamer inception time delay. A larger electrode size will increase the boost time delay, statistical time delay, and its dispersion of bundle conductor + rod electrode, they are closer to sim-worker's feet when the radius of bundle conductor + rod electrode is 5 cm.