Open AccessInfluences of surface tips of a shield ball on the discharge characteristics of a long sphere‐plane air gap under positive switching impulses
Author(s) -
Geng Jianghai,
Lv Fangcheng,
Ding Yujian,
Zhao Yingyu,
Li Peng,
Wang Ping
Publication year - 2018
Publication title -
iet science, measurement and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.418
H-Index - 49
eISSN - 1751-8830
pISSN - 1751-8822
DOI - 10.1049/iet-smt.2018.5287
Subject(s) - shield , ball (mathematics) , materials science , air gap (plumbing) , mechanics , plane (geometry) , ball lightning , acoustics , surface (topology) , optics , physics , geometry , composite material , plasma , geology , mathematics , petrology , quantum mechanics
The study established a test platform for a long sphere‐plane air gap in the test hall of the ultra‐high voltage (UHV) direct current(DC) Testing Site. Under the sphere‐plane gaps with 3, 5 and 7 m distance, the study carried out the experiment on discharge characteristics under switching impulses on a shield ball on which surface tips had different lengths at different locations. By comparing with the test data obtained under conditions with a smooth surface of the shield ball and the same gap distance, the discharge laws under the influence of surface tips on the shield ball are shown as follows: the presence of the tips greatly decreased the discharge voltage of the sphere‐plane gap with the maximum decrease amplitude of 39.0%. Moreover, the decrease degree was increasingly significant with the growing length of tips. The influence of the same length of tips on the discharge voltage of the gap gradually declined with the growth of the gap distance. The presence of tips significantly reduced the discharge voltage, especially in the perpendicular line of the shield ball. The results indicate that it's necessary to strictly control the machining and installation to avoid the occurrence of tips in UHV DC engineering.