Analysis of anode thermal process of vacuum arc

Summary form only given. Arc in vacuum circuit breakers operates in a diffuse mode in the low current range and transfers into a constricted mode when current is high. The constriction of the arc column leads to the concentration of current density and enhancement of heat flux density at the anode surface and further results in a rapid temperature rise of the anode material. Localized high temperature approaching the boiling point of the anode material is one of the necessary conditions for the formation of anode spots. Excessive anode erosion produces a vapor jet directed away from the anode surface, which constitutes a major cause of interrupter failure in vacuum circuit breakers.