Intelligent Monitor And Control For Gas Concentration Of SF₆ Based On Ultrasonic And CPLD Techniques

Some problems on the project, which is aided by the forth science and technology program of Changzhou and the development program of high and new technology industrial of Jiangsu, are discussed in this paper. And some technologies of the project is protected by two patents: a patent for invention(200510037936.2) and a patent of utility model(200520069403.8).In half year before my master degree studying, the author was luck to study and experiment in the state key laboratory for the sound field simulation and gas concentration detection and established the good base of the paper. After project being received, author researched the SF₆ concentration detecting system based on the former work of mine and others. The detecting theory of this system is binary gas mixtures theory of ultrasonic. SF₆ concentration transducer is developed adopting norm-contrast method. Given the resolution and the request of real-time processing, the CPLD&MCU technology is used to reach high-resolution and high-rangeability. The transmitter can detects oxygen concentration, temperature and relative humidity(RH), which is regulated by criterion. Basing on the data sent from transducers, master controller makes corresponding decision such as exceeding SF₆ concentration alarming, lacking oxygen alarming and fan running and so on. And the master is the manager of the whole system with the function of data enquiry. In order to reduce the disturbance at maximal degree, the paper developed a anti-jamming solution that take account of PCB, interfaces, software and so on to improve the anti-jamming quality of whole system. The RS485 bus is used to construct the communication network of the system, and basing on the characters of master and slaves, a user-defined facing to shake-hands communication protocol based on layering is developed. A relative independent voice processing system is designed to assist the system by reminding the worker entering the GIS field to look over detecting data, avoiding some dangers and enhancing the security management.This system is consisted of transducers, communication network, master controller and protection setting for worker and integrates many high technologies such as ultrasonic detecting, CPLD&MCU, serial communication, voice processing technology and MCU anti-jamming technology. The design and realization of transmitter, communication network, master-controller, life-safety protection device are by and large finished. And the paper is groping for the project-applying ways of this system.