The research and development work toward a compact SF$_6$-free load break switch for the medium voltage range has led to several design proposals. The interruption capability of three different nozzles and gas flow concepts with atmospheric air as the interrupting medium is compared and assessed. The three test switches are installed in circuits corresponding to the mainly active load and switch-fuse test duties of the 24 kV/630 A load break switch standard. A pressure tank is used to provide different air flow rates, and the interruption capabilities of the different flow concepts are compared with basis in the tank pressure required to give successful interruptions. Two hundred and seventy current interruption tests were carried out. Air flows directed radially onto the arc or swirling along the arc turn out to result in a substantially better interruption performance than when the air flows straight and parallel to the arc. Air flows corresponding to upstream over-pressures of a few tenths of a bar seem to be sufficient for an air-based load break switch rated for 24 kV/630 A.

中文翻译：

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中压负载断路开关不同气流概念的比较

针对中压范围的紧凑型无 SF$_6$ 负载断路开关的研究和开发工作导致了多项设计建议。比较和评估了三种不同喷嘴和以大气作为中断介质的气流概念的中断能力。三个测试开关安装在对应于 24 kV/630 A 负载断路开关标准的主要有源负载和开关熔断器测试任务的电路中。压力罐用于提供不同的空气流速，并将不同流量概念的中断能力与成功中断所需的罐压力的基础进行比较。进行了 270 次电流中断测试。与空气直线平行于电弧流动时相比，径向引导到电弧上或沿电弧旋转的空气流导致明显更好的中断性能。对于额定为 24 kV/630 A 的基于空气的负载断路开关，对应于上游十分之几巴的过压的气流似乎就足够了。