地面长导线发射机电流快速关断技术研究

Research on fast current turn-off technology of long wire transmitter on ground

发射机是地面人工源电磁勘探的关键装备,在相同发射电流条件下,极距越大,信噪比越高,探测效果越好.大极距所需长导线具有较强电感(地面1 km导线约有3 mH电感),发射电压1000 V,发射电流50 A,3 mH电感的电流关断时间为103.95μs,对于时间域电磁勘探,观测信号的信噪比与关断时间对数成反比,关断时间每下降10倍,信噪比提升10 dB.本文通过在发射回路中加入快速关断开关,引入辅助关断电压,形成电流高压释放回路,有望实现1 km长导线条件下的关断时间小于10μs,观测数据信噪比提高10 dB以上,具有重要的理论意义与工程价值.

Transmitter is the key equipment for electromagnetic exploration of ground artificial source.Under the same transmitting current condition,the larger the pole distance and the higher the signal-to-noise ratio,the better the detection effect.The long wire required for large pole distance has strong inductance(about 3 mH inductance of the 1 km wire).The current turn-off time of the 3 mH inductor is about 103.95μs under the condition of 1000 V transmitting voltage and 50 A transmitting current.For electromagnetic exploration in the time domain,the signal-to-noise ratio of the observed signal,which is inversely proportional to the logarithm of the turn-off time,improved by 10 dB with the turn-off time decreases 10 times.In this paper,by adding a fast turn-off unit to the transmitting loop and introducing an auxiliary turn-off voltage to form a current high-voltage release loop,the turn-off time under the condition of 1 km long wire is expected to be less than 10μs,and the signal-to-noise ratio of observed data is increased by more than 10 dB,which has important theoretical significance and engineering value.