Contact welding at break of motor inrush current

The contact welding phenomenon observed at automotive relays at switch-off of a dc motor load during startup was investigated. Contact welding occurred during the first operation and was caused by anodic arcs shorter than 80 mus at breaking inrush currents of up to 85 A. The switching performance of the type of relay investigated could be correlated with the parameters: over-travel, release time, and the break current