磁带直接测量雷电流最大陡度的方法与机制

The Method and Mechanism of Measuring Directly the Lightning Supreme Steepness Using Tape

雷电流最大陡度是导致二次设备电磁感应过电压、输电线路反击过电压的关键参数。统计表明,电力系统事故中50%与雷击有关,而在雷击事故中有50%与雷电流最大陡度有关。将两条互相垂直的预录有基准信号的同型号磁带同时置于雷电通道旁,可实现直接测量雷电流最大陡度。文中建立了雷电流产生的磁场对磁带磁化的物理及数学模型,并定义磁力线垂直穿过一条磁带正面为磁带水平放置,垂直穿过磁带侧面为磁带垂直放置。研究表明:水平放置磁带的消磁长度由雷电流产生的磁场强度和在磁带中感应的与其陡度成线性关系的感应电流共同产生;垂直放置磁带的消磁长度仅与雷电流产生的磁场强度有关,而其感应的电流对磁带的消磁长度可忽略不计。故计算两条磁带的消磁长度差可直接测出雷电流最大陡度。经实验验证,该测量方法误差小于5%。

Lightning supreme steepness is the key parameter for induced over-voltage of secondary equipment EMI and over-voltage of transmission line back striking. According to the latest statistics, there are about 50% of the accidents in the electric power system caused by lightening strike. Half of the accidents caused by lightening strike are caused by the max lightning steepness. The two mutually perpendicular and same types of tapes with Pre-recorded benchmark signal are placed beside lightning channel, and then the lightning max steepness will be measured directly. Establishing physical and mathematical models, which describe the magnetic field generated by the lightning current magnetize magnetic tape, When the magnetic curve cuts through perpendicularly tape front face, the magnetic tape is horizontal placement, and the magnetic curve cuts through perpendicularly tape side face, the magnetic tape is vertical placement. Enunciated by study： The length of erased magnetic record of horizontal placement are together engendered by the magnetic field intensity and by the induction current which is induced in tape and is in line with the lightning steepness, and both of them are generated by the lightning current. The length of erased magnetic record of vertical placemem is only influenced by the mognetic field intensity, but the induction current may be ignored to the length of erased magnetic record. So computing the difference of two-tape length of erased magnetic record can find out the lightning max steepness. Verified by experimem, the error margin of the measure method is less than 5%.