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When short current is interrupted in three-phase vacuum interrupter in switchgear, the “U”-type loop composed of external busbar, conductive rod, and vacuum interrupter, and its adjacent phases will generate external actual transverse magnetic field (EATMF) in the interrupter. The existence of EATMF will deflect the vacuum arc, which will affect the breaking performance of vacuum switch. In view of this situation, this article establishes two kinds of electrode system simulation models considering and not considering EATMF. The simulation results show that EATMF is not uniformly distributed in the interelectrode region, but is stronger in the contact cup edge area outside the “U”-type loop, weaker in the “U”-type loop, and mainly affects ${B} _{x}$. In different short-circuit cases, EATMF is also different due to the difference of phase distance and short current. In the case of three-phase short circuit, the magnetic field in the interelectrode region of the middle phase is most significantly affected by EATMF. EATMF is closely related to the structure size of vacuum switch. By changing the structure size of vacuum switch (e.g., phase spacing ${d}$ , conductive rod length ${h} _{1}$ , ${h} _{2}$), EATMF can be weakened to some extent. [ABSTRACT FROM AUTHOR]

The degradation of the electrical contact in a gas insulated switchgear (GIS) is closely related to overheating at the contact. However, the disconnector contact is one of the hot contacts in GIS. Therefore, in this paper, the finite element method was used to solve the three-dimensional multiphysics coupling temperature rise field and flow field in the Single Phase in One Tank (SPIOT) type GIS disconnector under different operating conditions. From the perspective of temperature rise field and flow field, this paper analyzed the temperature rise characteristics under different working conditions and explored the feasibility of the direct application of air, CO2 and C4F7N/CO2 mixed gas to an electrical device. The disconnector temperature rise experiment platform was then built to verify the simulation. The results showed that the temperature rise field and the flow field distribution were similar in four gas environments. SF6 gas had the smallest temperature rise, followed by C4F7N/CO2 mixed gas, and the temperature rise of CO2 and air was relatively large. Therefore, from the perspective of the temperature rise field and flow field, it was feasible to directly apply C4F7N/CO2 mixed gas to an electrical device in order to meet insulation requirements. [ABSTRACT FROM AUTHOR]