本质安全电路中的热点燃

Thermal Ignition in Intrinsically Safe Circuits

对于热点燃的考核,一直是整个行业尤为关心的话题。本质安全电路中电子元器件的实际耗散功率会在温升方面表现出来,根据傅立叶热传导方程推理出的热阻系数,并以晶体管为例进行热阻估算,进而得出电子元器件最高表面温度计算方法。参照国家标准GB/T 3836.4-2021的评定方法 ,简述电路的连接导线及PCB上的印制线设计原则,为本质安全电路中的热点燃评估提供了理论指导。

The assessment of thermal ignition has been a particular concern of the whole industry. The actual power dissipation of electronic components in intrinsically safe circuit will be shown in the aspect of temperature rise. According to the thermal resistance coefficient deduced from Fourier heat conduction equation,and taking transistors as an example,the thermal resistance is estimated,and then the calculation method of the maximum surface temperature of electronic components is obtained. According to the evaluation method of national standard GB/T 3836.4-2021,the design principle of connecting wire of circuit and printed wire on PCB is described briefly,which provides theoretical guidance for thermal igniting evaluation of intrinsically safe circuit.