An Experimental Study of Arc Duration and Transition from Metallic to Gaseous Phase in Ag Alloy Break Arc

We have studied maintaining mechanism of the contacts arc discharge. In our experiment, the arc duration ta, metallic phase arc duration tm, and transition ratio from metallic to gaseous phase arc G were experimentally studied in Ag, AgCu and AgSnO₂ breaking contacts. Experiments were carried out under the variation of source voltage E (12, 24, 36, 48 V), closed contact current Io (0.4 - 6 A). As a result, the gaseous phase transition was not occurred in E=24 V or less. In addition, gaseous phase transition boundary closed contact current (at which G=50 %) of AgSnO₂ was smaller than that of Ag and AgCu contacts. It was clarified that the Io which ta and tm increases rapidly is corresponding to the transition boundary from metallic to gaseous phase arc.