程控电话交换机过电流保护PTC陶瓷元件参数及耐流特性

Parameters and Current-shock Resistant Characteristic of PTC Element As Over-Current Limiter for Program-Controlled Telephone Exchanger

程控电话交换机过电流保护元件是ＰＴＣ陶瓷材料的主要应用之一．这一元件要求ＰＴＣ陶瓷具有低电阻率、高耐电压强度特性，且对ＰＴＣ陶瓷元件过电流保护工作原理分析可知，其安全电流值（不动作电流）和过电流的动作时间之间存在着相互制约的关系，因此必须综合考虑陶瓷材料的居里温度、室温体积电阻率以及元件的几何尺寸等参数，才能得到满足实际要求的过电流保护元件．承受大电流冲击能力是这种ＰＴＣ陶瓷元件的主要性能之一，适当调节ＰＴＣ陶瓷材料的体积电阻率随温度变化曲线的斜率，有助于改善元件承受大电流冲击能力．

PTC element as over-current limiter for program-controlled telephone exchanger is one of the important application of PTC ceramic material. High performance material for this element is required with low volume resistivity and high voltage withstanding. Some parameters should be carefully considered for the application, such as volume resistivity, Curic temperature and dimension of the element. It is proposed to adjust the slope of ρv-T curve for PTC material and improve the shock -resistant capability of inrush current of the element.