Research And Development Of Power Cable Fault Detector

With the development of electric power industry, the structure and scale of the network are becoming increasingly complex and large, and the probability in which the fault occurs are also becoming more and more great. How to detect the cable fault fast, accurately and economically has become an urgent and necessary technological problem.The characteristics of the power cable faults are studied, and the power cable fault detector based on the low-voltage pulse reflecting principle is developed and the development ideas are detailed under the support of Natural Science Foundation of Educational Municipality of Guangxi Zhuang Autonomous Region.The power cable fault detector can be used to detect many kinds of faults such as open circuit and short circuit of cable, bad contact and earth fault. It can also detect the length of cable and propagation velocity of the electromagnetic wave along the cable. Practical test indicates that the system is prompt, accurate and convenient to locate the fault.In the paper, the hardware design of the power cable detector prototype is firstly presented, in which the design of keyboard- interruption circuit, high-speed sampling module, data processing cell and waveform display interface and device type selecting are detailed, with emphasis on the generation, transmission, reception of the high frequency pulse with the pulse width adjustable by high-speed CPLD.And then the software design is considered. In which the programming of CPLD, master controller and slave controller is concerned with, and the method for utilizing waveform concatenation of ADC sampling twice to improve samplingfrequency is described.Finally, the experiment of detection of short circuit and open circuit of many kinds of cables are performed. From the results it can be seen that the waveform of the fault is clear and can be easily identified, and the leading edge of the waveform of reflecting pulse is steep, the location error is small.