Research On H₂O Concentration Detecting System Of SF6 In GIS Instruments

With the rapid development of the electric power industry, more and more SF6 electrical equipments are used. The quality monitoring of SF6 gas is more important than before. Although the pure SF6 gas has excellent insulation and suppressing arc performance, SF6 gas in the electrical equipment is inevitable to mix other gases, such as H2O and air. Under the arc action, H2O can easily react with the decomposed product of SF6, and then produce poison which can corrupt electric equipment, degrade its insulation performance. If the content of H2O exceeds the norm, it will strongly influence the electrical, mechanical and on-off capability of equipment, which will result in a serious consequence.In this paper, the significant meaning of detecting H2O concentration (humility) about SF6 , which applies to the electrical equipment, is discussed. The appropriate method of humidity are selected for H2O Concentration Detecting System with comparing and analyzing the features about existent theories at home and abroad. Moreover, the whole design of it is summarized.This system has high intelligence, stable performance, powerful function and simple operation. The ARM hardware platform centralize on S3C44B0 is development. It consists of A/D conversion module, LCD display module, Key module and RS485 communication module. With the making of PCB and debugging completed, boot code of the system and the application program are compiled in ADS1.2 for ARM, and the remote monitoring software are compiled. And then the debugging of the whole system is accomplished based on the hardware circuit. Finally, calibration experiments are done in the laboratory.Compared with the traditional sensors, the infrared sensor for density detection designed in this paper is characterized by rapid respond speed, long service life and good adapting for adverse circumstance.With the ARM embedded processor, this system has advantages of good real-time performance, offline operation and portability, which will take up a favorable portion in application market.