Anode mode diagram: A determination of opening displacement curve for a 126kV vacuum circuit breaker

The objective of this paper is to experimentally determine an opening displacement curve based on the vacuum arc anode mode diagram of a 126 kV single-break vacuum circuit breaker. The experiments were carried out in a LC discharging circuit. In this experiment, a pair of 2/3 coil-type AMF contacts, with a diameter of 100 mm and a contact material of Cu50Cr50, were installed in a demountable vacuum chamber. Experimental results show that there were two significant contact gaps 20(±2) mm and 40(±2) mm corresponding to the minimum arcing region and the maximum arcing region respectively. The opening velocity of 3.5 m/s in the minimum arcing region was appreciable as the vacuum arc can transfer out of the intense arc mode region very soon. While in the maximum arcing region, the opening velocity of 3.0 m/s was appreciable as the duration of the opening displacement maintained in the footpoint mode region and the anode spot mode region can be relatively shorter.