Iron-type bipolar AMF (axial magnetic field) contact is one of the common types in high voltage vacuum interrupters. For exploring the formation mechanism of the uncontrollable arc mode of the iron-type bipolar AMF contact vacuum interrupter during arcing process

the AMF characteristics of the contact are tested

simulated and studied. The contact magnetic field measurement platform is set up by using the Hall effect sensor array. The AMF distribution of the iron-type bipolar AMF contact at 1-15 kA is measured. The correctness of the magnetic filed simulation model of the iron-type bipolar AMF is verified by the actually measured results. The AMF saturation characteristics at 1-40 kA and the AMF dynamic variation between contacts during arcing process at 40 kA are further analyzed. The results show that the AMF of the iron-type bipolar AMF contact shows remarkable saturation trend after the current is higher than 10 kA. Due to the existence of AMF saturation

the variation curve of magnetic field with time during high current arcing process will be distorted for a few milliseconds near the current peak. The AMF saturation phenomenon and the attenuation of the AMF with the increasing of contact clearance jointly lead to the appearance of uncontrollable arc mode during the high current arcing process of the contact. The study in this paper can deepen the understanding of the arc control process of the iron-type bipolar AMF contact and has guidance for the design of the iron-type bipolar AMF contact.