Research On Electrical Life Prediction Of AC Contactor

AC contactor is a widely used low-voltage electrical apparatus, which is often used toswitch on and off AC or DC circuits. It is usually used to control a motor and also used inother electrical power loads, such as power units, electric heater and electric welder. It has theadvantages of great capacity control, remote operation and so on. So the AC contactor has thebroad using space in automation field and arouses attention from domestic and foreignresearch field recently.At present, the design of AC contactor has been perfected gradually. However, theresearch on the state monitoring of AC contactor is not mature, especially the prediction of itselectrical life state has a great research space. This paper mainly focuses on theoreticalresearch and experimental research in how to predict the electrical life state of AC contactoraccurately.First, the theoretical basis for predicting the electrical life of AC contactor is discussed inthis paper. Through the research and exploration of the theory, a method of electrical lifeprediction of AC Contactor based on wavelet analysis and grey theory is firstly proposed inthis paper. Then the processes and the advantages of algorithm for electrical life prediction ofAC contactor are discussed in detail.Second, according to IEC, GB standard and electrical life test standard, the experimentalplatform for the whole life experiment of AC contactor is self-constructed. The basicinformation of AC contactor, experimental condition, experimental requirement, design of theexperimental circuit and experimental equipment are discussed in detail. At the same time, therationality of the experimental platform is verified.In addition, in order to realize scientific management and friendly interface, using thegraphical programming language–Labview developed a data acquisition and processingsystem of low-voltage apparatus. The system mainly includes four modules, data controlmodule, parameter setting module, data acquisition module, data processing and storagemodule. Around the four main modules, carries on the detailed description of the systemincluding design concepts and design advantages of each module. Finally, through the processing and analyzing of the large number of electrical lifeexperimental data, the contact resistance values are selected as feature parameter and thewavelet transform is used in the signal multi-resolution analysis to extract its trend changes asthe grey input sequences. Then the gray GM (1,1) model is used to predict electrical life stateof AC contactor. The results show that the proposed method can effectively overcome theerrors that reflected by hardware and environment factors and the prediction error is less than10%. Compared with the traditional electrical life methods, the forecasting result of thismethod is more accurate and smaller error. In addition, the theoretical method is correct andeffective in this paper.