Field Vacuum Interrupters Research Articles

Optimization of Three-Dimensional Magnetic Field in Vacuum Interrupter Using Particle Swarm Optimization Algorithm

Based on particle swarm optimization algorithm, a three-dimensional model of the contact system of vacuum interrupter is established. Combined with the particle swarm optimization algorithm and finite element magnetic field numerical simulation method, the contact structure parameters of a 400V/20kA vacuum interrupter is taken as the optimization variables, and the maximum magnetic field intensity at the arc root is determined as the optimization objective. The distribution of the maximum transverse magnetic field intensity at the contact gap under the optimum parameters has been illustrated and analyzed.

Vacuum Arcs and Postarc Characteristic of Vacuum Interrupters With External AMF at Current Zero

In order to reveal the mechanism of the residual magnetic field in vacuum interrupters (VIs), the vacuum arcs and the postarc characteristic with external AMF at current zero are investigated. The magnetic field of the 10-kV/20-kA VIs is analyzed. And then, the phase shift and the residual AMF are obtained. The test platform is established in the synthetic test circuit. The pulsed AMF is applied at current zero with the pulsewidth of 4 ms, and the magnitude can be adjusted from 0 to 200 mT. The transparency VIs with external AMF at current zero is observed by the high-speed CMOS camera to analyse the vacuum arcs development. The postarc current and transient recovery voltage are measured by the postarc current measuring equipment and the voltage divider so that the postarc characteristic such as postarc current and postarc charge can be obtained. The influence of the pulsed AMF at current zero on the vacuum arc development and postarc characteristic is gained and the mechanism of the AMF at current zero is analyzed, which can be useful to special AMF contact design for different applications.

Numerical Investigation on Residual Axial Magnetic Field in Vacuum Interrupter in DC Interruption Based on Artificial Current Zero

The residual axial magnetic field (AMF) at current zero, which is caused by large $\mathrm{d}i/\mathrm{d}t$ during the forced current-zero stage of DC interruption based on the technique of artificial current zero, has a significant influence on the interruption performance of the vacuum circuit breaker. In this paper, a model of AMF contacts system is developed by finite-element-analysis software Ansys. The eddy current induced in the contacts system is also analyzed by an equivalent circuit. The influence of the frequency of countercurrent and the characteristics of saturable reactor, which results in the change of $\mathrm{d}i/\mathrm{d}t$ before current zero, are investigated. The results demonstrate that the frequency of countercurrent has a significant influence on the residual AMF at current zero. The residual AMF decays exponentially after current zero with a time constant independent of the countercurrent frequency. The residual AMF can be reduced by using a saturable reactor. The effect of a saturable reactor depends mainly on the duration of the low $\mathrm{d}i/\mathrm{d}t$ stage before current zero.

A utility optimization method of a high voltage vacuum interrupter design

In this paper, a new method of electric field design of high voltage vacuum interrupters is proposed. According to the multi-gap insulation effect and the vulnerable breakdown spots theory, the symmetrical voltage shields are proved to be effective. So the initial model of a high voltage vacuum interrupter is designed. Next with finite element methods and optimization theory, a mathematical model of electric field intensity in interrupters is given. What's more, by optimizing this model with finite element software, a more symmetrical electric field in vacuum interrupters is obtained and its peak value appear as in the second auxiliary gaps (the two gaps between the center floating shield and the symmetrical voltage shields). The result shows that with this method, the vacuum interrupters can withstand higher static breakdown.