Analysis On Arc Duration And Experiments Of Electrical Contacts

In switchgear, the electrical contacts take function of connecting and breaking electrical circuit. The arc between contacts makes contacts working under bad conditions ,which greatly decline the reliability and endurance of the electrical contacts. So the research on arc characteristics is very important, and arc duration is the master parameter to denote arc characteristics, which can be used to analyze the safety reliability and working life of switchgear.This paper summarized all influence factors of the arc duration, and the key point is that the ascending of electricity source voltage affect the arc duration very much. but the research about this field is lack in both home and foreign countries. So arc characteristics of the low-voltage switches are analyzed, a universal V-I characteristics equation is deduced , which is used to create a new mathematic model between arc duration and voltage. Since the transient waveforms and voltage wave of the breaking and making process of contacts include abundant information, such as arc duration. Two data acquisition system are built in this paper to get a lot of wave signals. The dummy equipment based onLabVIEW adopt the moving-average ways to pick up the arc duration of every disjunction voltage. The analysis result of experiment show: the increasing multiple of arc duration does not make the direct ration with increasing multiple of electrical source's voltage; the higher of voltage , the quicker of arc duration's increasing trend; the bounce not only appear in the close process, but also in the open process, and the bounce decline with the increase of voltage.The simulation result of the mathematic model are in good agreement with the test data. The model can reflect the rule of the arc duration's shifting with the change of voltage, and point out that the arc duration increase with ascending of voltage. The model works well both in the resistive and the inductive load in the large range of the current.