Study On Electrical Contact Perfomance Of Air Circuit Breaker Terminals In The Salt-spray Environment

Air circuit breaker, as the most powerful and important switch in the low-voltage distribution system, is responsible for connecting, bearing and breaking current in normal and abnormal conditions. When the product was put into the actual environment, the metal conductor is easily got corroded by different atmosphere, such as sulfur dioxide, H2 S, salt spray, dust, etc. Pollutants in the coastal area are mainly composed of salt spray. The contact surface,which is composed of copper base layer and silver-plated, have generated a poor conductivity of the corrosion products by the micro pores’ electrochemical corrosion. This condition will directly affects the electrical contact, increasing contact resistance even cause the failure of the contact. The influence of electrical contact is becoming one of the important problems that users are much concerned.This paper aimed to investigate the influence of electrical contact by putting the samples into salt spray test chamber and contact resistance as the appraisal indicators of electrical contact performance.What’s more, developed equipment that can precede auto-complete contact resistance and analysis the text data at the same time. The equipment used the four-terminal method to measure contact resistance. The samples were connected in series and texted by switch detection channel one after another.In the end, the paper illustrated the modeling idea and grey prediction, and processed the experimental data with curve-fitting and grey prediction. In addition, to ensure the accuracy, the model of residual errors were processed as well. The results was used to predict whether the main circuit would invalid by single salt spray factor within the lifetime setted by manufacturers.