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The paper investigates the influence of the pulsed AMF arc control on the vacuum arc and the post arc characteristic to reveal the mechanism of AMF arc control in different control time and find the proper AMF arc control. The pulsed AMF control system is designed and the pulse width is adjusted from 1.5 ms to 10 ms by changing the capacitors. The test circuit is set up in the synthetic test circuit and the test vacuum interrupter (VI) is transparent in order to observe the development of the vacuum arc by the high speed CMOS camera. The rated voltage and current of the test VI is 10 kV and 25 kA respectively. The post arc current of the test VI is measured in order to analyze the post arc characteristic, such as the post arc charge, post arc conductance and dynamic dielectric strength. The development of vacuum arc and the post arc characteristic influenced by the pulse width, magnitude and control time of the pulsed AMF is obtained, which is useful to special magnetic contacts design. [ABSTRACT FROM AUTHOR]

In the present study, FeOOH/γ-Al 2 O 3 catalyst was first introduced into dielectric barrier discharge (DBD) plasma-catalysis system for toluene degradation, and its catalytic performance and mechanism were studied. It was found that the toluene degradation efficiency, energy yield (EY), and CO x selectivity were significantly improved in the plasma-FeOOH/γ-Al 2 O 3 system by comparison to the plasma-only process. The ozone concentration detected in this study decreased significantly in plasma-FeOOH/γ-Al 2 O 3 system, which could be concluded that the ozone catalytic process played an important role in the plasma-FeOOH/γ-Al 2 O 3 system for toluene degradation. The toluene and intermediates adsorbed on the surface FeOOH catalysts could react with O* from O 3 decomposition and O ads derived from oxygen vacancies, which was conducive to an improved degradation and mineralization performance. Besides, the transformation of O 3 to·OH on FeOOH surface was considered as one of the main mechanisms for enhancing toluene degradation when the relative humidity of the background gas was increased from 30% to 50%. The key process parameters, including specific energy input (SEI), catalyst loading, and oxygen content of the background gas, were optimized by response surface methodology (RSM) integrated Box-Behnken design (BBD). The results showed that oxygen content of the background gas was the most significant factor affecting the degradation efficiency of toluene, while energy yield was mainly determined by SEI. The possible toluene degradation pathways in plasma-FeOOH/γ-Al 2 O 3 system were proposed according to the identification of intermediates using GC-MS. • Toluene degradation was improved using FeOOH/γ-Al 2 O 3 catalysts in a dielectric barrier discharge (DBD) plasma reactor. • The possible mechanism for toluene degradation by plasma-FeOOH/γ-Al 2 O 3 system was proposed. • The catalyst enhanced toluene degradation through the transformation of O 3 to·OH. • The response surface method was used to optimize the experimental operating parameters. [ABSTRACT FROM AUTHOR]

The current-zero characteristic of vacuum circuit breakers (VCBs) has an important influence on the dynamic dielectric recovery and the success of the breaking test. In the paper, the characteristic of the post-arc current, post-arc charge and the post-arc conductance at current-zero is researched to obtain the influence of the arc memory on the current-zero characteristic and the post-arc characteristic. Based on the synthetic test circuit, the test plat of the current-zero characteristic is set up and the test VCB is a transparency vacuum interrupter in order to observe the development and extinguishing process of the vacuum arc by the high speed CMOS camera. The distribution law of post-arc characteristic is gained by measuring and processing the post-arc current. The relationship between the post arc charge and the final position of last cathode spot is investigated. The current-zero characteristic of VCBs supply the base for controlling vacuum arc, improving the breaking capacity, which maybe also useful to VCBs with multi-break. [ABSTRACT FROM AUTHOR]

In tank-type multi-break vacuum circuit breakers (VCBs) and gas-insulated switchgear (GIS), the non-uniform distribution of vapor shield potential in the vacuum interrupters impacts the post-arc process significantly. To explore the effect of the vapor shield potential on the development of the post-arc sheath, a particle-in-cell model with shield potential control is proposed to obtain two-dimensional distributions of post-arc particles. Based on the synthetic test circuit and probe array, the test platform of the post-arc characteristic diagnostic is set up to verify the influence of vapor shield potential distribution on the post-arc sheath. The extinguishing process of the vacuum arc is also observed by the high-speed CMOS camera. Simulation and experimental results show that at shield potential of 0.5 transient recovery voltage, the post-arc sheath develops most rapidly and the distribution of cathode spots is the most uniform. These findings can provide valuable insights for the design of vacuum interrupters and the control of shield potential in tank-type GIS. • A new structure of series special self-voltage sharing vacuum interrupters in tank-type circuit breakers or gas insulated switchgear is proposed. • A PIC simulation model for the post-arc sheath development in the vapor shield potential control of vacuum interrupters is established. • A probe diagnostic approach is employed to analyze the decay process of post-arc residual plasma in vacuum interrupters. • The vapor shield potential affects the development process of the post-arc sheath, with the best effect observed when the shield potential is at 0.5 TRV. [ABSTRACT FROM AUTHOR]