Simulation and Experimental Investigation on a New Type of Cup-Shaped Contacts With Iron Cores

Vacuum interrupters, with the advantages of high breaking ability, small volume, low weight, and little pollution, are widely used in medium voltage circuit breakers. The transverse magnetic field (TMF), generated by spiral-type or cup-type contact, moves the constricted arc over the contact surface, which avoid excessive heating on the contact and reduce the erosion of a fixed area. The TMF contacts are slotted to cause current flow diversion, and a radial magnetic field is produced. In this paper, we propose an improved cup-type contact with iron cores. The magnetic field distribution of this new contact was simulated, and the magnetic force acted on arc column was calculated. It was found that the optimized contacts could effectively enhance the radial magnetic field between contacts and reduce the radial force of the arc column. In addition, two different kinds of cup-type TMF contacts were investigated in a demountable vacuum chamber using a high-speed charge-coupled device video camera. The experimental results suggested that compared with the traditional cup-shaped contacts, the new contacts could effectively improve the arc speed and duration of arc movement, accompanied by a more evenly surface ablation and an improved surface utilization.