直流熔断器低过载电流的开断性能优化及其结构设计

Optimization and Structure Design of Low Overcurrent Interruption Performance of DC Fuse

由于直流熔断器加工时的固有工艺误差,其在低过载电流下熔体易发生仅有部分狭颈燃弧的现象而导致熔断器出现过热、喷弧等故障,因此判断熔体是否会燃弧不均及燃弧不均下如何开断短路电流成为熔体设计的难点。针对这一问题,建立电弧燃弧过程数学模型及熔断器弧前过程的热电耦合模型,对不同条件下熔体起弧狭颈数量进行计算。在此基础上提出设置阶梯式狭颈的解决方案,以保证电流成功开断,改进设计额定800V/300A的直流熔断器并进行过载电流开断试验,结果表明该试品成功开断了500 A、1 kA及10 kA短路电流。试验结果验证了该设计方案的可行性和有效性,相关结论可应用于指导熔断器的设计。

Due to the inherent inaccuracy during the manufacrure of DC fuses, only part of narrow necks arc are likely to occur under low overcurrent, which leads to the malfunction of fuse, such as overheating and arc spray, thus it is difficult for melt design to judge whether the melt will have uneven arc and break short circuit current under uneven arc. To solve this problem, a mathematical model of the DC fuse arcing process and a thermoelectric coupling model of the DC fuse pre-arcing process are established to calculate the number of arcing narrow necks under different conditions. The results of the calculation will provide a solution to set stepped narrow neck to ensure the successful breaking of current. A DC fuse with the rated 800 V/300 A is improved and designed, and the fault current breaking tests are carried out. It is proved that the testing products have successful broken 500 A, 1 kA and 10 kA overcurrent. The results verify the feasibility and effectiveness of the design, and the relevant conclusion can be used to guide the design of the DC fuse.