Research On Condition Assessment Method Of AC Contactor Based On Multi Information Fusion

AC contactor as a frequently breaking switchgear,is a control of electrical appliances.The control object is the motor,but also control the electric heater,welding machine and power units such as power load.It is widely used in low-voltage distribution system,which is a very important low-voltage electrical appliances,so its safe and stable operation of the grid is also very necessary.In order to ensure its safe and stable operation,it is able to monitor its state in real time and make timely and effective response.In recent years,with the development of online monitoring technology,it is more and more popular to evaluate the status of electrical equipment based on large data.Therefore,taking CJX2-80 as an example,this paper studies the design of the test platform,the extraction of characteristic parameters,the denoising and the state evaluation.First of all,the subject designs and builds AC contactor life test platform,including coil drive circuit,signal acquisition circuit and signal conditioning circuit.This test system software used the LabVIEW graphical programming language for modular design,including PC data acquisition,data Storage,data playback and data processing program modules.In this paper,the main circuit voltage,main circuit current,fracture voltage,coil voltage and coil current are monitored.The parameters such as contact resistance,arcing time,arcing energy,pull-in time and breaking current are obtained by calculating or extracting the waveform signal characteristics.Secondly,the data obtained in the experiment contains a lot of noise,which can interfere with the state assessment,making the state assessment inaccurate,and therefore need to filter denoising.In this paper,wavelet transform with good nonstationarity and multiresolution analysis is used to denoise.In the wavelet transform,the threshold and the number of wavelet layers are chosen very carefully,because the two of them are directly related to the effect of noise removal.So after wavelet transform and other means of pretreatment,the signal feature is extracted and the corresponding characteristic parameters are obtained.Finally,based on the analyzed and pretreated data,grey fuzzy comprehensive evaluation is used to evaluate the state of AC contactor.This method fully considers the grayness,fuzziness and randomness in the evaluation,and makes the evaluation more accurate.Themost important of this method is the calculation of weight and the generation of grey fuzzy judgment matrix.The grey part is obtained by expert scoring.The modulus of the weight is determined by the analytic hierarchy process,and the gray fuzzy judgment matrix is obtained by the triangular membership function.