Asynchronous Motor Protective Device Based On Network

Asynchronous motor ,which is one of the most popular kinds of motors ,is widely used in the corporate enterprises .According to statistics ,power drive ,most of which are three-phase AC asynchronous motors ,accounts for about 60 percent of the total load in the power networks .So it's greatly significant to prohibit the three-phase AC asynchronous motor from damage accidently.In recent years, with the development of computer technology and electronics, computer integrated protection systems with the core of the microprocessor are put into service. Compared with the traditional system of protection, the new protection system has powerful logic analysis and processing capabilities .The fault can be recorded and analyzed too .And this significant advantages become the main developing direction of motor protection device. The comprehensive protection of the electrical system researched in this paper is under this background.This theory of symmetrical components method is used to analyze the varieties of symmetrical and asymmetrical faults of motor, and the measuring method of negative and zero sequence is adopted in this paper. Especially the protection of overload condition is researched. The motor faults of over-loading, short circuit, phase failure, over-voltage, under-voltage can be dealt with by the device.The device with the 32bits MPU AT91SAM7S64 designed. The hardware of the device consists of monitoring and control parts, signal conditioning and output control modules, analysis and processing modules, interactive modules, communication modules, and the practical programs is designed, by making full use of MPU AT91SAM7S64 powerful capture function to outside event and strong ability of treatment to signal ,a new type of motor protective device is designed.