The Study And Exploitation Of AC Motor Multi-Functional Protection And Communication System

With the development of electronics and microcomputer, microprocessor-based protection has advanced. But some of them are just the republication of the electromechanical and electronic proteciton. They can not fully utilize the computing capability and logic judgement that the computer has and most of the microprocessor-based protection is running isolated. There is little data exchange with outside.This thesis introduces the research of one asynchronous motor multi-functional protector. The protector makes the over-current value, zero-phase-sequence component, negative-phase-sequence and so on as protection criterions,in protection theory; it makes ATMEL 8-bit microprocessor AT89C55WD as the core,with which the lattice LCD is linked, in hardware. It has follow characters: Chinese display, operation with menu-guided software, fault diagnosis, parameter setting simple and flexible, perfect protection functions and so on. Furthermore, two kinks of Field Bus -PROFIBUS and MODBUS are applying to the motor protector. A industry PC is used as the network server, and all the protectors are used as network nodes. In this way, we realy realize the automatic control, the centralized control and the intelligent self disposal functions of the motor protection.The thesis emphasizes the implication of PROFIBUS and MODBUS on motor protector and introduces the design of Field Bus in hardware and software separately, makes a detailed analysis to the interference accaused by high voltage and great current and puts forwards the corresponding measure.Furthermore, the paper introduces Chinese display, the hardware experimental circuits and the whole design philosophy of its software together with some program flow charts.