Study Of Squirrel Cage Asynchronous Motor On-line Monitoring System

Asynchronous motor can be found everywhere in modern life, especially the squirrel-cage asynchronous motor. With the progress of modern science and technology level, its operating requirement is becoming more and more stricter. Because of the influence of its working environment, the work loads, the voltage quality and its working life and other factors, faults in motor often occur. The automation, intelligence and integration make the connection between each link more and more closely in modern industrial production. If one of the motors in the production line breaks down, a large number of products may scarde, which makes the whole production equipment be unuseful forever and it may do harm to the staff’s personal safety even. So online monitoring to the operating state of the asynchronous motor is very important.Aiming at the above problem, the squirrel-cage asynchronous motor on-line monitoring system have been carried on the detailed research. First, this paper analyzed the common failures such as rotor bar breaking, air-gap eccentric and stator winding inter-turn short circuit. According to the analysis for these mechanism failures, this paper has got the characteristics of various kinds of faults in motor and determined the extraction method of the fault signal; it also studied the mathematical models both in normal and in failure operation. Then this paper designed the hardware circuit and software program of the on-line monitoring system of the squirrel-cage asynchronous motor. The hardware design and software design are the core part of the on-line monitoring system. The hardware design includes signal acquisition circuit, signal conditioning circuit, A/D conversion circuit, frequency multiplication phase-locked circuit, display circuit, communication circuit, storage circuit, etc. The software design of the system includes the main program, data acquisition program, data processing and display program, etc. At last, this paper has verified the accuracy and feasibility of the on-line monitoring system by simulation in Matlab with all of the operating conditions in motor. The on-line monitoring of the squirrel-cage asynchronous motor used different sensors and transformers to detect the voltage and current of the motor and dealt with these signals. We need assess to the current working status of the motor and analyze the fault types when malfunction occurs and display the alarming information. This motor on-line monitoring system is based on computer as the core of the monitoring and automatic alarm system. It monitors and controls the motor on operation。The motor on-line monitoring system this paper studied can judge the squirrel-cage asynchronous motor running state accurately and find the failure of the motor early which can remind staff to deal with it in time. Eventually this monitoring system can effectively reduce the economic losses motor faults caused, improve the efficiency of the motor and it can also reduce the threat to the staff. This on-line monitoring system can store the history running information of the motor. Workers can download the information at any time they want to ensure the better monitoring of the motor.