Research Of Failure Prediction On Electrical Contact Of Contacts

For the electrical apparatus, the contact is the on-off contact, belongs to one kind of the heaviest burden contact modes. So it is the weak parts of electrical apparatus. The relay is a kind of switching apparatus used widely. So, it is of very important signification to study the contact reliability and contact failure of the relays' contacts. The paper involves the relation between the contact failure and the characteristics of some parameters. These parameters come from the waves of the dynamic contact resistance in the closing process of HH52P electromagnetic relays under different temperature. The characteristics include the parameters' change-time characteristics and statistics characteristic. Further, combine the time series analysis with the fuzzy synthetical evaluation method, theoretically set up the model for the evaluation and prediction on the electrical contact reliability.In the paper, some prediction methods and the fuzzy synthetical evaluation method are studied in detail. Based on the time series analysis and the fuzzy synthetical evaluation method, the evaluation-prediction model and the prediction-evaluation are modeled. Using them, the evaluation and the prediction on the system state can be carried out.By the measurement system for testing the dynamic contact resistance, the contact resistances of the HH52P electromagnetic relays are measured for a certain interval in the closing process of relays. And their waves are monitored. Five eigenparameters (the static contact resistance, the maximal contact resistance in the closing process, the bounce time, the vibration time and the transition time) are distilled for describing these waves. And the static and dynamic contact performance are analyzed. Study on the change-time characteristics and the statistics characteristics and find:1) Each value in the measured values series of any eigenparameter appears in uncertain. But concentrate in a certain field and takes on a certain trend (level trend or uptrend) as a whole. And the uptrend eigenparameters come from the failure contact.2) Under the same temperature, the eigenvalues (average and standard deviation) of the same eigenparameters are close to each other, so are the probability distribution of them.3) The environment temperature has heavy influence on the static contact resistance and the maximal contact resistance in the closing process. But has less influence on the bounce time andthe vibration time.Take analysis on the three phenomena above and draw a conclusion that the contact reliability has close relation to the change-time characteristics and the statistics characteristics.In view of the parameters characteristics and their relation with the contact reliability, abstractly base on the nonlinear smoothing prediction model (time series analysis) and the two-level fuzzy synthetical evaluation model (fuzzy synthetical evaluation method), advance the synthetical evaluation and prediction method of the contact reliability of contacts (contact system state), quantificationally study the contact reliability in primary.