直流真空电弧强迫开断电弧形态

Morphology of Forcing Interruption Arc of DC Vacuum Arc

随着航空270V直流系统的应用,直流开关的需求逐渐增加。现阶段直流开关大多为空气开关,其开断容量较小,使用真空开关将对于提高开断容量具有一定优势。针对航空270V直流用短间隙真空灭弧室进行高频开断实验,研究了直流强迫开断的电弧电压、电流特性,分析了回路参数对直流强迫开断中平均电流变化率di/dt和弧后过电压dv/dt的影响。通过相同开断实验电流、相同电流变化率、不同触头结构情况下开断实验,分析了电弧直径动态特性。强迫熄弧过程中,平板触头电弧直径逐渐减小,纵磁触头电弧直径变化较小并在熄弧前迅速变化。针对不同电流实验,随电流升高电弧直径略有增加。起弧阶段,平板触头电弧直径随燃弧时间呈对数函数增加,而纵磁触头电弧直径基本保持不变。拟合得到平板电弧起弧时直径变化函数,随燃弧时间延长,平板触头电弧直径逐渐增大至大于纵磁触头电弧直径。

With the applications of DC270V system in aviation field, the demand for DC switch has increased. At present, DC switch is mostly air switch, its switching capacity is small. For high capacity DC switch, vacuum switch has many advantages. According to the experiments of short gap vacuum DC interruption on DC270V system for aviation, the arc voltage and current characteristics of DC arc forcing interruption are analyzed. The impacts of the circuit parameters on the current rates di/dt, overvoltage rates dv/dt and their coupling situation are discussed. Under the same test current, the dynamic characteristics of arc diameter are studied. In forcing phase, the arc diameters of butt contacts decrease smoothly, while the AMF arc changes little, and has a sharp shrink before it quenches. Arc diameter increases slightly with the increase of the test current. At arc ignition stage, the arc diameters of butt-type contacts increase logarithmically, while the AMF arc is unchanged. The function of butt contact arc diameter is obtained. The arc diameter of plate contact is larger than that of the AMF before the forcing current injects.