Research On Portable Discharge Fault Detecting System Based On Ultraviolet Radiation

There have been more than 40 years since Boeing and Airbus series civil aircrafts were put into operation. Many aging aircrafts which have operated over 15 years are still in service in civil aviation community. Aging aircrafts are prone to raising electrical wiring faults, such as short circuit, wire overload, adhesion of relay contacts, slack bus bar and so on. The discharge fault may cause a fire disaster even air crash when the situation is severe. Problems still exist in usual detecting way of discharge fault in civil aviation field. This thesis focuses on developing a"solar-blinded"discharge fault detecting system in consideration of excellent performance of ultraviolet detection technology. If the detecting system is put into the market, efficiency of seeking electrical wiring fault will be greatly improved, and will contribute to raising our county's technology level in aircraft maintenance area.The portable discharge fault detecting system based on ultraviolet radiation is a type of embedded device which blended in ultraviolet detection technology. The system is separated into two modules in hardware design, and they are sensor part and master control part. A solar-blinded ultraviolet photosensitive tube is chosen as photoelectric sensitive element of the system in the sensor module, and through two-stage booster circuit to provide 350V DC for the ultraviolet photosensitive tube. The signal processing part includes a frequency selective amplifier and a normal amplifier, which can extract the weak desired signal from the noise. In order to provid high quality pulse signal to the master control module, a filter based on fuzzy algorithm has been designed to process the signal after A/D conversion. The master control module centered on ARM7 microprocessor includes several sub-modules, such as LCD display, keyboard, SD card interface, and power management circuit. The real time operation system (RTOS) kernelμC/OS-Ⅱis transplanted into the ARM7 microprocessor in software design. And application program of each sub-module is developped on the basis of drivers. The programs as a whole compose a friendly embedded operation system, which enhance the operability of the detecting system.The system has been tested in the laboratory through detecting two types of ultraviolet radiation source. Results of the testing show that the system can detect ultraviolet radiation source effectively whose energy is between 5 mJ and 1 kJ when the distance is 5 m, and the average response time of the system reduces to 506.8μs. Indicators of the system are better than other devices in relevant areas. The portable discharge fault detecting system, which is high performance and maneuverable, will have a rosy prospect in discharge fault detecting area.