High voltage DC contactors, for operation at voltage levels up to at least about 300,volts, find their increasing markets in applications such as electrical vehicles and aircrafts in which size and weight of cables are of extreme importance. The copper bridge-type contact, cooperated with magnetic field provided by permanent magnets and sealed in an arc chamber filled with high pressure gases, is a mainly used structure to interrupt the DC arc rapidly. Arc characteristic in different gases at different pressure varies greatly. This paper is focused on the arc characteristics of the bridge-type contact system when magnetic field is applied with nitrogen and gas at different pressure. The pressure of the gases varies from 1,atm to 2.5,atm. Arc characteristics, such as arc durations at different stages and arc motions in those gases are comparatively studied. The results are instructive for choosing the suitable arcing atmosphere in a DC bridge-type arc chamber of a contactor.

Bridge-type contacts are mainly used in high voltage direct current contactors for their performance of arc extinguishment and break capacity. It is also easy to add external magnetic field in them to blow the arc. Experiments on the arc behaviors were carried out when a copper bridge-type contact pair opening a 270V resistive circuit in the air. Influences of the shape of the movable contact, the opening speed and the magnetic flux density on the key behaviors, such as the arc duration, the arc re-ignition and the stability of arcing process, were investigated by using an oscilloscope and a high-speed camera. It was revealed that a uniform magnetic field with proper density could extinguish the arc stably and could reduce the arc re-ignition.