Development Of Low-voltage Electrical Monitoring And Protection Devices

The project described here is from a co-operational project with Xuji Changlong Company. The aim of the project is to develop an equipment that can monitor and protect the motor. The equipment can measure voltage, current, temperature of a running motor. The equipment judges whether the motor is in trouble or not by analyzing the measuring data. It can detect the faults of motor such as reversal, phase-lacked, phase unbalance, creepage, overload, blocking, short circuit, low voltage, low current and protect the motor.The project investigates various known equipments on market and determines the goals based on the requirements of Changlong Company. The device is so designed that it is composed of ADC, MCU, liquid crystal display module, data RAM and controlling circuits. Then the key ICs are choosed carefully. ATT7028 is selected for power measurement and digital signal processor because of many challenging advantages. The DSP is selected as MCU in this project for future complex algorithm of motor faults. Furthermore, it can improve the speed of analyzing measuring data and performance of the system. The reason for choosing liquid crystal display module-EMD12864P is that we can have a friendly user's interface.The main hardware designs include the interface between DSP and ATT7028, the interface between DSP and EDM12864P, the interface between DSP and data RAM, the communication interface of DSP, the controlling circuits etc. The software designs include the communication program, the driving program of EDM12864P, the scanning program of keyboard. Both the hardware design and the software debugging have been fullfilled.