Experiment and Simulation Study on the Breakdown Current, Velocity, and E-Field in Air Gap Discharge

• Published in: IEEE transactions on electromagnetic compatibility 2020-04, Vol.62 (2), p.324-329
• Main Authors: Huang, Liyang, Zhang, Qi, Wang, Jianbao, Duan, Yantao, Chen, Hailin, Shi, Lihua, Gao, Cheng
• Format: Article
• Language: English
• Subjects: Air gap discharge; Air gaps; Breakdown; breakdown current; Coils; Computation; Computer simulation; current impulse velocity; Current impulses; Current measurement; Cylindrical coordinates; Discharge; Discharges (electric); E-field; Electrodes; Finite difference time domain method; Ground level; Optical variables measurement; Propagation velocity; Time domain analysis; Velocity; Velocity measurement
• ISSN: 0018-9375; 1558-187X
• DOI: 10.1109/TEMC.2019.2909402

The breakdown current, current impulse velocity, and E-field in air gap discharge are of interest among researchers on high-voltage engineering and lightning study. It is the breakdown current and current impulse velocity that govern the radiated E-field property. The current impulse velocity, however, is not well addressed in the literature. In this paper, we use a self-developed high-speed observation system, a Rogowski coil, and a transient E-field sensor to measure the current impulse propagation velocity, breakdown current, and vertical E-field in the rod-to-plane discharge after the air gap breakdown under dc voltage. From the time difference of arrival of light signals in different receiving channels, the resultant current impulse propagation velocity is measured as 6.81 ± 0.57 × 10 6 m/s. Meanwhile, the breakdown current at the bottom of the grounded rod electrode has a peak value of approximately 1.3 kA and 10%-90% rise time of 40 ns, and the transient vertical E-field at ground level has an amplitude of approximately 15 kV/m and 10%-90% rise time of 64 ns. In addition, according to the measured breakdown current and resultant current impulse velocity, the vertical E-field is computed by using the finite-difference time-domain method in the two-dimensional cylindrical coordinate system. The computed vertical E-field agrees well with the measured E-field, validating our measured current impulse velocity. Besides, the computed horizontal E-field and azimuthal H-field are also analyzed. Finally, the influence of current impulse velocity on the vertical and horizontal E-field and azimuthal H-field is discussed.