Investigation on Arc Asynchronous Characteristics of the Double Bridge-Type Contacts in DC Relays

The asynchrony of the multi-break dc relay has an important influence on its arcing characteristics. Through the experimental test platform, the arc characteristics of the single bridge-type contact and the double bridge-type contacts are compared. Arc images are acquired through high-speed photography. On the basis of asynchronous action, the influence of action speed and overtravel difference on arcing characteristics is analyzed. A multi-breakpoint asynchronous arc model is established to study the nonlinear relationship between overtravel difference and arc duration. The distribution characteristics of the double-bridge arc are analyzed. Experiments and simulations show that the double bridge-type contacts have better arc-extinguishing characteristics. Increasing breaking speed is conducive to reducing arc energy difference between fractures. When the overtravel difference is small, the bridge <inline-formula> <tex-math notation="LaTeX">$B$ </tex-math></inline-formula> (bridge with larger overtravel) arc can enter the diffusion state, and the arc voltage of bridge <inline-formula> <tex-math notation="LaTeX">$B$ </tex-math></inline-formula> is higher. Reducing the overtravel difference can effectively reduce the arc duration.