Opening velocity characteristics for vacuum interrupters with cup-type axial magnetic field contacts

摘要

The objective of this paper is to experimentally determine an opening velocity for vacuum interrupters, with cup-type axial magnetic field (AMF) contacts. The opening velocity characteristics of the VCB includes an initial opening velocity v1 and an average opening velocity v2. The initial opening velocity v1 is defined as an average velocity in 1/2 full contact gap of 20 mm. The average opening v2 is defined as an average velocity of full contact gap. Experiment result shows that a higher v1 always decreases the duration for the intense arc mode. However, a higher v2 tends to result in an earlier formation of anode spot mode. The preferred initial opening velocity v1 should higher than a threshold velocity v1_th, at which the peak critical contact gap dI_th is achieved, for the intense arc mode evolving into diffuse arc mode. The preferred average opening velocity v2 should be at a threshold velocity v2_th, at which the maximum critical contact gap dII_th is achieved, for the diffuse arc mode evolving into the large-gap active-anode mode. The lower of v2 below the v2_th the better, as the large-gap active-anode mode would be avoided.