Study on Excitation Characteristics of 2/3 Coil-type AMF Contacts under Equal Proportion Structure in Vacuum Interrupters

The objective of this paper is to investigate the excitation characteristics of 2/3 coil-type AMF contacts with equal proportion structure in vacuum interrupters, which is aimed at the prediction of the interrupting capacity of the large size contacts. Simulation models of 2/3 coil-type AMF contacts for 126kV vacuum interrupter with equal proportion structure were built. Through the simulation of AMF excitation characteristics between the contacts gap, the change law of AMF characteristics with equal proportion structure in vacuum interrupters was determined. The results indicate that the AMF flux density at current peak between the contacts gap is almost inversely proportional to the scaling ratio of the contact structure. A function expression of I
th
and solid angle D/l was obtained. Meanwhile, modified by published experimental results, the prediction function of the critical short-circuit breaking current of the 2/3 coil-type AMF contacts was obtained.