Mechanism Of Magnetic Card And Appliance On Measuring Parameter Of The Lightning Supreme Steepness

Measuring of lightning parameters is the base work of lightning research. It is very important for researching the lightning characteristics, analyzing the accident of lightning, identifying the responsibility of lightning strike outage accident and discussing the strategies of lightning protection. It also can provide precise original data for designing insulation co-ordination. The max lightning steepness has the important significance to the base researching work of the lightning-protection and the lightning characteristics. For example, According to the latest statistics, there are about 50% accidents caused by lightening strike in the whole accidents in the electric power system. Half of the accidents caused by lightening strike are caused by the max lightning steepness. Based on the importance of measuring the lightning supreme steepness, this paper deeply discussed the measuring mechanism of the lightning supreme steepness and the mean of measuring appliance in engineering fields, and used the magnetic card with the magnetic layer of the best recording effect metal tape to detect the lightning parameters.The paper is mainly made up of the following parts. Based on the theories of Electromagnetic fields, the first is to establish physical and mathematical models, which describe the magnetic field generated by the lightning current magnetize magnetic tape, and discuss the measuring mechanism of the lightning supreme steepness.The second part is to make references to the principle of the magnetic card reader existed, and to make the magnetic card and magnetic card detector, whichfocused on appliance in engineering fields.The third part is to develop the program about the magnetic card waveform process using Matlab software. The program can get the info of lightning parameters in the signal of waveform and calculation the length of erased magnetic record.Fourthly, we fix kinds of channel models of lightning current by which to generate artificial lightning current using the impulse big current generator. Then put the magnetic cards on the channel models in different ways to detect the lightning parameters. And we analyze the difference of length of erased magnetic record between two magnetic cards, and find the max lightning steepness. Then we can calculate the regression curve about length of erased magnetic record and the max lightning steepness. Last we analyze the error of recording data.This Study in this paper shows that the induction current and the magnetic field generated by lightning current effect together on the two tapes, the length of erased magnetic record are not sameness, when the manner of the two tapes placement is not sameness. So computing the difference of two-tape length of erased magnetic record can find out the lightning max steepness. The proposed method is superior to the present method for the lightning current measuring in the economical, practicability and precision of measurements. This is significant for analyzing lightning accident completely and accurately and finding out the cause of lightning accident as aspect of lightning steepness. Magnetic card detector can offer a new way for developing highly precise lightning census in large region from lightning steepness, and drawing the probabilistic distribution curve of lightning supreme steepness.