Effect of switching interval on some characteristics of relay contacts

Abstract

A normal, open electrical contact pair, mounted in a small relay, was used to make and break repeatedly a dc, 3OV13 P resistive circuit up to 100 thousand times; and the relationship between data for each switching and switching interval are analyzed in this paper. Four kinds of switching intervals are set by changing the frequency of applying the rated voltage to drive the electromagnetic coil.No special relationship was found between four differeat switching operation intervals and data for bounce number at make, arc duration at m a k e l b d , and contact resistance at 500 ms after the 10-A current began to flow.On the other hand, the following points became clear through the experiments.-Temperature at the backside of contacts at 500 ms after the 10-A current began to flow changes drastically by the difference of the switching interval.-Temperature rise changed linearly and was proportional to the contact resistance at each switching interval.-The more frequent the switching interval, the larger the proportional coefficient.By these results of experiments, the following facts were concluded.-Temperature of electric contact increases with Joule heating of contact resistance and the resistance of the conductor including supporting arms.-The shorter the period of the separated contacts, the larger the temperature difference between measuring point and room temperature became.