Leader discharge characteristics of equipotential live-line work gaps under positive switching impulse

The leader discharge is the primary process in long air gap discharge. However, there is currently a lack of detailed observation of the development process of leader discharge in equipotential live-line work (EPLW) gaps. Therefore, this study utilizes an electrical and optical synchronous observation platform to measure the key parameters of leader discharge in two typical EPLW gaps with gap distance of 2 m–3.5 m. Research results indicates that the worker's posture has significant effect on the leader characteristics of EPLW gaps. The longer the length of the worker's body-parts stretch out the bundle conductor and the small diameter of the discharge part is, the lower the leader inception voltage and inception current are. The average leader velocity of worker facing the tower is 5.93–7.67 cm/μs, however the leader velocity of worker facing the conductor is 7.43–9.59 cm/μs. The bending frequency of the leader channel of these two typical EPLW gaps both rise with the increase of gap distance. The axial deflection angle of worker facing the conductor gap is 27.87°, which is larger and more dispersive than that of worker facing the test tower gap. These test results can provide important references for determination of minimum approach distance and optimization of equipotential entering path for live-line work.