To find a criterion effectively representing the transition from high resistance to low impedance condition of gas discharge tubes (GDT), following electromagnetic induction law, a method according to the analytic and the experimental comparison with the existing technology, is proposed, where a coupling coil and whose primary coil are set in series in the main circuit to extract the weak impulse current in case of broken down GDT as the criterion signal. Once modeling for circuit state in the breakdown GDT, the reasons for the impulse current on the circuit view point are revealed, and different impulse current waveforms are considered as the interaction between current impulse component and linear one. The experiments indicate that in the measurement system with a wide testing voltage range (50~5 000 V), the steady-state breakdown current gets lower than 5 mA, the minimum delay time takes 2. 06 μs, the maximum 3. 34 μs, and the average 2. 81 μs, with a 100 V/s rising rate.%为了寻找一个能有效表征气体放电管(GDT)从高阻状态转变为低阻状态的判据,在分析和实验对比现有技术的基础上,提出了利用电磁感应原理设计判据提取的方法.该方法设计了一个耦合线圈,将初级线圈串入主回路采集GDT击穿瞬间产生的微电流脉冲,将该脉冲整形后作为判据信号.对GDT击穿瞬间的电路状态进行了建模分析,首次从电路角度分析了GDT击穿瞬间出现的脉冲电流的形成原因,并指出不同的脉冲电流是由电流中脉冲分量和线性分量相互作用的结果.实验结果表明:在宽电压范围(50～5 000V)测量系统中,稳态击穿电流小于5 mA,且在上升速率为100V/s直流电压作用下,从GDT击穿到系统响应最小时间为2.06μS,最大为3.34 μS,平均为2.81 μS.
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