Theoretical and Experimental Investigation of New Innovative TMF-AMF Contacts for High-Current Vacuum Arc Interruption

This paper consists of investigating the vacuum arc behavior during the high-current interruption process with a new innovative coaxial double-contact system. The structure of the so-called TMF-AMF double-contact offers the advanatage of low total resistance for nominal current conduction as in standard transverse magnetic field (TMF) contacts and similar vacuum arc control as in axial magnetic field (AMF) contacts. For an optimized contact's geometry, finite element method B-field simulations were performed to evaluate the effect of geometric parameters on the axial B-field strength and distribution and mechanical simulations to evaluate the closing forces 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 commutation to 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.