An Experimental Study on Contact Dynamic Welding under Different Contact Materials and Surrounding Atmospheres in HVDC

Contact dynamic welding is a common failure fault of high voltage dc (HVDC) relays. Contact materials and surrounding atmosphere have important influences on the dynamic welding of sealed relay contacts. In this paper, the anti-welding abilities of CuW50, CuW60, AgW60 and Cu contacts are researched in six kinds of ambient atmospheres such as N
₂
and CO
₂
under the conditions of 200 - 500Vdc and 40 - 150A. The results show that: O
₂
has normally the strongest anti-welding ability among all tested atmospheres. The welding force in the gas mixture of 80%CO
₂
with 20%Ar is usually smaller than that in 50%CO
₂
with 50%Ar. Mixed gases show an "optimal effect" and an "intermediate effect". AgW60 possesses fewest numbers of welding among all of the tested materials, and Cu, the second-fewest. In terms of welding force, mostly it turns out that AgW60 is smaller than Cu and CuW50 is smaller than CuW60.