Detection Technology For Failure Types Of Relay Based On Image Recognition

Relay is not only quick, small, stable, durable, but also it is widely used in remote control , correspondence , electric power protection, automatic control, and other systems .Relays must be tested after it is produced, and relay electrical life is one of the important tests; after the test, we can not only get the indicators of the test, but also the relay failure reasons so as to improve the way of relay design. So, electric study pay more attention to the way, device and standard of relay electrical life test.In classical relay electrical life test, detecting the switched on or off voltage is used to judge if the relay is failure or not. Since the cycle of relay electrical life test is so long that the power is instantaneous off in some unexpected situations in the loop including the excitation coil. In that case, the relay can't work well, either. So it seems to be unreliable by the way of simply voltage checking. In order to prevent an error of judgment on relay failure, the paper used image recognition to observe and record the state of relay contacts. The paper firstly introduces the contact state recognition system, made up of industrial control computer, image acquisition card and CCD camera; it is used to get result of picture recognition after capturing and processing the image when the relay is failure to check if the relay is really failure or just error judgment; secondly, the paper design the hardware and software of the contact state recognition system; finally, it presents the method of how to judge the relay failure types. The aim is that the computer can judge whether the test sample woks well and show the type of relay failure by comprehensive analysis, using the mixed information about the current closed / disconnected state of the test sample contacts and surveyed voltage between contacts.Software is the core of the system design. Control and show of image acquisition is designed in LabVIEW environment, the same as the relay data acquisition in the test. Calling dynamic-link library is to use LabVIEW and general image acquisition card; the method can not only save money, but also can edit the human-machine interface by LabVIEW; it designs the color image processing algorithm, in the space of YCBCR, do image segment, characteristic acquisition and result classification based on the theory of color similarity analysis, mathematical morphology and binary image; program it by MATLAB. Finally,the paper gives the rules for judging failure types of relay after introducing the contact state recognition.