183 / 2024-04-15 18:09:00

Research on the Insulation Characteristics of Series-connected Structure of Two Vacuum Interrupters

Insulation Characteristics,Dynamic Insulation,Two Vacuum Interrupters Connected in Series,SF6 Substitution,Restrike and Arc-reignition

The rapid development of vacuum switching technology and environmentally friendly gas insulation technology opens up new avenues for SF₆-free high-voltage switchgear development. Currently, high-voltage vacuum circuit breakers for transmission voltage primarily employ two technical solutions: single vacuum interrupter and multi-vacuum interrupters in series. However, a thorough comparison of these two approaches in both theory and experiment, particularly regarding the static and dynamic insulation characteristics of the structure composed of two vacuum interrupters in series, has somewhat constrained their application in transmission-level switchgear. This study primarily investigates the insulation characteristics of double vacuum interrupters in series compared to single vacuum interrupters with long opening distances, focusing on both static and dynamic insulation aspects. In the aspect of static insulation, the voltage withstand capability of double vacuum interrupter in series with the same total opening distance is compared with that of single vacuum interrupter with long opening distance under power frequency and lightning impulse voltage. In the assessment of dynamic insulation, the restrike probability of these two structures is compared under different transient recovery voltage (TRV) subsequent to the rated short-circuit current interruption. Theoretical analysis and experimental findings indicate that the structure of two vacuum interrupters in series can effectively leverage the exceptional characteristics of a short vacuum gap, resulting in superior voltage withstand and insulation performance under the same total opening distance. I Moreover, during the process of arc restrike to arc reignition, any restrike event transpiring in one of the double interrupters may be impeded by the presence of the other interrupter. Consequently, relative to a single interrupter, the series-connected double-vacuum interrupter structure demonstrates enhanced short-circuit current interruption capability and a reduced likelihood of reignition. Hence, it is recommended that the evolution of vacuum switches towards power transmission levels should be centered around the adoption of double vacuum interrupter units.