High current vacuum arc investigation with new innovative TMF-AMF contacts

This work consists in investigating the vacuum arc behavior during the high current interruption process using a new innovative co-axial double-contact system. The so-called new TMF-AMF contact structure offers the advantage of low total resistance for nominal current conduction as in standard TMF contacts and similar vacuum arc control as in AMF contacts. For an optimized contact´s geometry, FEM B-field simulations were conducted to evaluate the effect of geometric parameters on the Axial B-field strength and distribution. The arc dynamics for two distinct cases, where the arc ignition takes place between the inner contacts, and between the outer contacts, are investigated experimentally. The arc appearance extracted from the high speed movie is correlated with the arc voltage to explain the mechanisms of arc commutation to fully diffuse mode. It has been shown that the arc commutation to the fully diffuse arc takes place in all cases but with a shorter commutation time with the second case. The benefit of using the present TMF-AMF contact system for high current interruption while keeping the total nominal resistance as low as possible is demonstrated.