摘要
SPD在遇上较高的故障过电压后,MOV熔穿不可避免,但熔穿后短路并不是通常理解的零阻抗短路,热态下,它仍有数欧至数十欧的阻值,其短路电流极少能达到100 A以上,这使得用作SPD前端保护的空开很可能不跳断,从而造成SPD起火并持续燃烧。避免SPD起火燃烧的关键在于保证击穿喷火的热量能快速传导至热脱扣焊点熔化低熔点合金,使热脱扣动作脱离。这既涉及到SPD的热脱扣设计是否合理,也涉及到MOV的工频耐受能力及其击穿点区域的控制技术。
It is inevitable for MOV to burn out in the case of SPD stressed by extreme overvoltage. But such burning out would not result in short circuit with zero impedance, and the impedance after burning out is still of a few ohms even to tens of ohms so as to the short circuit current cannot exceed 100A in most cases. This will lead the air switch as front protection of SPD not to trip in time and cause firing in SPD. The key point to avoid SPD firing is to transfer the hot energy caused by breakdown to alloy with low melting temperature as soon as possible and to lead to the alloy melting in order to cause the thermal trip to disconnect. Based on the discussion above, the rational thermal tripping design in SPD, the high capability of transient overvoltage withstand in MOV and the melting region controllingtechnology should be taken into considerations.
出处
《电瓷避雷器》
CAS
北大核心
2013年第6期87-90,共4页
Insulators and Surge Arresters
基金
贵阳市科技型中小企业创新基金资助项目:筑科合同[2012201]43号
贵阳市高新区中小企业创新基金资助项目(编号:GXCX2012-007)
