SPD脱扣装置中温度保险丝性能分析

金属氧化物避雷器(MOV)对电子设备和网络系统提供有效防雷保护的同时也出现了因MOV失效所导致的诸多问题,其中最严重的是导致起火、爆炸。分析了MOV起火的原因,阐述了温度保险丝的工作原理,提出运用温度保险丝对MOV进行过热保护,防止MOV起火的观点。为检测温度保险丝的性能,设计了温度保险丝的过电流耐受冲击试验、限制电压试验和热稳定性试验。试验结果表明:使用温度保险丝作为电涌保护器内置脱扣装置时,能够耐受雷电流的冲击;压敏电压的变化率在10%以内,限制电压仅上升2.2%,说明温度保险丝并不会影响MOV的限压性能;在MOV过热时,温度保险丝能迅速熔断,切断MOV与主电路的连接,从而保护系统安全。还对温度保险丝和低温焊锡的脱扣性能进行比较,将二者的脱扣温度与断开时间进行了分析,当脱扣时的温度小于130℃时,温度保险丝较低温焊锡动作及时,具有一定的优越性。

Performance Analysis of Thermal Fuses in SPD Disconnector

The malfunction of SPD can incur many problems.The most hazardous problem is the fire and explosion resulted from the failure of MOV（Metal Oxide Varistor）.The reasons for the fire are analyzed and the working mechanisms of thermal fuses are described.The method using thermal fuses to protect SPDs from excessive heating and MOV fire is introduced.In order to test the characteristics of thermal fuses,the tolerance impulse overcurrent,the voltage limiting,and thermal stability experiments are designed.The results indicate that using a thermal fuse as the arrester disconnector can stand the impulses of thunders.The change rate of the residual voltage is only 2.2%and the switching voltage is within 10% after the experiment.It shows that thermal fuses do not affect the voltage-limiting performance of MOV. When the MOV is over-heating,the thermal fuse can rapidly blow out and turn off the circuit to inhibit current to protect working systems.Comparison is conducted between thermal fuse and low-temperature soldering tin through thermal stability experiments.It is discovered that thermal fuses have certain advantages when the operating temperature is blow 130℃.