Developing Of Portable Impact Earth Test System

In2011,"7·23" Yong-Wen line High-speed crash has exposed the lightning proof problem in high-speed rail. High-speed rail lines in mountainous area, the soil resistivity of these is high. Grounding resistance will lift the top potential in lightning, which influence the safe power supply catenary. Therefore, carrying out the impact test of the tower grounding device and measuring the impact grounding resistance, this can improve the railway power supply security and ensure the safe operation of the high-speed railway.The traditional high voltage impact grounding device is too large, which Unable to carry out contact line tower grounding test. Therefore, we need a smaller and lighter device, in order to carry field experiment.This paper proposes a portable impact grounding test system, which has high electric generator, impact current in circuit, data acquisition, the MATLAB data processing and man-machine interface. The high voltage generator is the key to shrink the volume of the impact test equipment. This paper designed a2kV half bridge converter, which used to generate high voltage. The generator has the features of small volume, light weight, easy to carry and flexible to use.In the area of impact current discharge circuit, this paper reaches the RLC discharge circuit principle, determine the matching relationship of the pulse energy storage capacitance C and impulse grounding resistance R, and the relationship of allocate inductance L and wavelength time of the impact current wave.Data acquisition system is the key to the realization of digital processing. Because of the lightning current waveform’s head is a very short time, so I need a high speed data acquisition system. This paper uses S3C2440A+AD9248combination, which can realize to convert analog signal to digital signal. Data will be uploaded to a PC via a serial port transmission, then using MATLAB for data processing. Finally, design a man-machine interface based on MATLAB GUI.Thronging laboratory simulation circuit experiment verifies the feasibility of the system. Simulative impact current waveform, which generate by discharging circuit, is close to the lightning current waveform, which has good simulation characteristic. High-speed data acquisition system is reliable, which can collect accurate simulative current and voltage waveforms. MATLAB computation results close to the theoretical value. In conclusion, the reasonable design of this system is valid and feasible.