Relationship Between the Voltage Distribution Ratio and the Post Arc Current in Double-Break Vacuum Circuit Breakers

Abstract

In many cases, single-break vacuum circuit breakers are used as circuit breakers, and so the characteristics of doublebreak vacuum circuit breakers have not received sufficient attention. This report describes our investigations of the interruption characteristics of double-break vacuum circuit breakers. We have investigated and clarified the relationship between the voltage distribution ratio and the post arc current in double-break vacuum circuit breakers by measuring the post arc current in the single-break vacuum circuit breaker, the voltage distribution ratio, and the post arc current in double-break vacuum circuit breakers. Our investigation has shown that the post arc current scatter of the spiral contact is much larger than that of the axial magnetic field contact. This result shows that the bias of the voltage distribution ratio was caused by the imbalanced post arc current in each vacuum interrupter in the double-break vacuum circuit breaker. Therefore, we conclude that axial magnetic field contacts are suitable for double-break vacuum circuit breakers.Index Terms-Double-break vacuum circuit breakers, grading capacitors, post arc current, vacuum interrupters.

Study on transient recovery voltage distribution mechanism and grading capacitor of double-break vacuum circuit breaker

“…5 shows the simulation results of the TRV distribution ratio under three different combinations of contact structure (AMF/AMF, SP/AMF and AMF/SP) when the double-break VCB interrupts a current of 10 kA rms . The experimental results of the TRV distribution ratio under the same conditions are U 21 :U 10 =50%:50% for AMF/AMF, 46%:54% for SP/AMF, and 54%:46% for AMF/SP, respectively [3]. The consistency between the simulation and experimental results confirms the validity of the mathematical model proposed in part II.…”

“…Results of repeated experiments indicate that the post arc current scatter and amplitude of the spiral (SP) contact are much larger than that of the axial magnetic field (AMF) contact [1]- [3]. This can be realized by changing the initial ion density in our simulations.…”

“…Adopting a grading capacitor in parallel with each vacuum interrupter (VI) is a major method of improving the even degree of the TRV distribution in double-break VCBs. The former researches [1]- [3] have indicated that the bias of the TRV distribution ratio is caused by the imbalanced post arc current in each VI. It has been shown [4] that grading capacitances above 1500 pF may lead to a decrease of the breaking capacity.…”

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

“…Because of the stray capacitances and imbalanced post arc current (PAC), the voltage distributions of the multi-break VCB are uneven and that directly influences the breaking capacity of the multi-break VCB. It is a method to set a grading capacitor in parallel with each interrupter to even the voltage distribution between the breaks [7]- [9]. In the case of simultaneously operated vacuum interrupters, the use of grading capacitors leads to an improved balance of the voltage distribution and improves the breaking capacity and the use of high values of grading capacitors does not lead to a further improvement of the breaking capacity [7].…”

“…It is advisable to limit the value of the capacitances to the range that guarantees sufficiently improved voltage distribution [8]. The bias of the voltage distribution ratio in double-break VCBs with grading capacitors is caused by the amount of charge that flows into the grading capacitor by the imbalanced PACs [9]. Series arrangements are known to be employed in some applications now, but the concerned research results are scantily published, especially the voltage sharing design of multi-break VCBs.…”