https://doi.org/10.1140/epjd/e2012-20544-4
Regular Article
The impulse dielectric behavior of N2 gas in sphere-plane gap
1
Department of Electrical Engineering, Shanghai Jiaotong
University, Shanghai
200030, P.R.
China
2
School of Electric Power and Automation Shanghai University of
Electric Power, Shanghai
200090, P.R.
China
a e-mail: flyhigher80@hotmail.com
Received:
6
October
2011
Received in final form:
24
December
2011
Published online:
1
March
2012
The focus of this work has been on the pre-breakdown phenomena and the breakdown characteristics of N2 gas in a sphere-plane gap under various impulse voltages. Both electrical and optical experimental investigation methods were used. Following parameters were considered: gas pressure range from 0.2 to 0.6 MPa, electric field utilization factor of the electrode configuration 71%, positive and negative impulse waveforms with the rise time of 500 ns, 1.2 μs and 180 μs. The observed discharge processes before the breakdown through the light emission images by the ICCD camera are in good agreement with the streamer mechanism. Under both polarity stresses, discharges are initially concentrated around the tip of the sphere and later pointing towards the earth electrode. However, negative streamers are thinner and more diffuse. As expected, the breakdown voltages for negative polarity are lower than those for positive polarity regardless of the gas pressure and shape of the applied impulse voltage. The breakdown voltage is increased with shortening the rise time of pulse waveforms. As a substitute for SF6, N2 gas under pressures above 0.3 MPa can reach the standard rated withstand voltage for 24 kV C-GIS.
Key words: Plasma Physics
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012