Equivalent Circuit Analysis for Transient Phenomena from Elastic Contact to Breaking Contact through Metal Melting

This paper explores the proposal of equivalent circuits of electric breaking contacts to analyze the transient phenomena from elastic metal contact to rupture. The time dependency of elastic contact resistance is derived from the actual measurement values with the low current condition. The equivalent circuit for the phenomena is divided into the three stages: the first stage from the energizing to the softening voltage U_s, the second stage from U_s to the beginning of the latent heat, and the third stage from the start of the latent heat to the melting at the melting voltage U_m. The accumulation of Joule heat at the contacts is shown with the capacitor in the circuits. The analytical result was able to qualitatively explain the complicated contact transient response characteristic of the Au crossing 1.0 mm φ rod experiment with source voltage 25 V, load current 2.5 A. Experimental results are compared with the fusion phenomena of conventional current fuse.