The Research Of Low Voltage Motor Intelligent Protective Device

Low voltage motor plays an important role in industrial and agricultural production.The development of iron and steel, smelting, petrochemical, coal and other heavy industrial sectors cannot do without for low voltage motor using. It is particularly important and provides timely and effective protection for faults that may occur during the running process of the motor. With the gradually mature development of modern electronic technology and microcomputer protection technology, because of its high sensitivity, low cost, strong operability, convenient maintenance and good communication function,intelligent motor protector based on microprocessor control has a broad application prospect in the industrial fields.On the basis of analyzing and researching the domestic and foreign existing computer protection technology, we use the MSP430F149 microprocessor of processing speed and power as the core to design and research low voltage motor intelligent protective device. It takes on strong logic analysis function and process function. It can realize complex protection mode of perfect performance. The fault judgment and recording function are the other perfect functions. In addition, we use MATLAB, combined with RS-485 bus and MODBUS-RTU protocol to develop a PC remote monitoring software. It realizes the bidirectional communication and networking between upper machine and lower machine.This article first analyzed fault characteristics of motor theoretically and analyzed the protection principle. We used full wave Fourier protective algorithm to complete operation. Combined with the specific needs, hardware circuit adopts a high precision integrated circuit design and it took the microprocessor as the main chip. The peripheral circuit structures mainly include signal acquisition and processing circuit, fault alarm and display circuit, key circuit and fault execution control circuit etc. The software design uses the modular programming and C language to complete in IAR Embedded Workbench integrated development environment. In addition, in the aspects of hardware and software anti-jamming design were studied to ensure the protection function efficiently and reliably executing.Through the actual test results and debugging show, the system can real-time monitor the parameters when the motor is running. And we can complete some fault modification, view and corresponding parameter setting function records with the liquid crystal display and PC monitoring software. In short, when some common faults occurduring the running process of the motor, such as locked rotor, over-voltage, phase failure,ground connection and so on, it can quickly identify and make the corresponding protective action.