Dielectric strength and statistical property of single and triple-break vacuum interrupters in series

Abstract

The maximum possible improvement factor of vacuum circuit breaker (VCB) with multiple breaks compared with one-break, which had the same total gap length, was deduced. Based on the research on the breakdown weak points in high voltage vacuum gaps, a theoretic model was set up for describing the statistical property of multi-break VCB. Dielectric experiments were carried out on a commercial vacuum interrupter arrangements with single break or triple breaks in series under lightning impulse voltage. It shows that the more numbers in series are, the higher the breakdown voltage improvement factor is. The statistical results show that the triple-break vacuum interrupters in series have lower breakdown probability compared with a single-break one. It can be demonstrated in a preliminary study that the experimental results confirm the previous theoretical studies.Index Terms -Breakdown voltage improvement factor, breakdown statistical property, electrode stress, breakdown weak points.Zou ji-yan was born in Liaoning province, China, in 1954. He received the Ph.D. degree in electrical engineering from the Xi'an Jiaotong University. He is currently a professor at Dalian University of Technology, China. He has been engaged in the study of vacuum circuit breakers.

Study on Static and Dynamic Voltage Distribution Characteristics and Voltage Sharing Design of a 126-kV Modular Triple-Break Vacuum Circuit Breaker

“…6. The value of the variable resistance is computed in a user-defined module by solving (1)- (5). Numerical integration is used to solve (1)- (5).…”

“…The value of the variable resistance is computed in a user-defined module by solving (1)- (5). Numerical integration is used to solve (1)- (5). To get more precise calculated results, we first calculated the PAC using the same voltage signals with the explicit Euler method and Runge-Kutta fourth-order method, respectively.…”

“…As for the saturation characteristics of dielectric strength of vacuum gap, the development of a single-break VCB of high voltage is restricted and that using a series arrangement of two or more breaks is considered to be a feasible method [3], [4]. Under the same total vacuum gap length, the triple-break VCB has a higher breakdown voltage and a lower breakdown probability compared with the single-break VCB [5]. The improvement factor of the breaking capacity of the double-break VCB without grading capacitors is above 1.3 compared with that of the single-break VCB, and reignition of one interrupter of the series arrangement does not necessarily lead to a breaking failure of the whole circuit breaker [6].…”

Self-voltage sharing effects of prebreakdown current flowing through vacuum interrupters in series

“…The essence of multiple-break VCB technology is connecting two or more small vacuum gaps in series to improve the withstand voltage. Making full use of the excellent characteristics of vacuum short gap is multiple-break VCB's greatest technology superiority [1].…”

“…Because of its numerous advantages, multiple-break VCB has become a hot issue in many countries. These researches focus on fields as follow: static insulation property [1]; dynamic insulation property [2][3][4][5]; operating mechanism and control system [6].…”