In this paper

the formation and the surface state of arc erosioa hollow of electric contacts in oil circuit breakers are analysed. An analytic model and an expression are set up on the temperature distribution along the electrode axis during the arc erosion. The changing mode of cooling temperature after the completion of the discharge between electric contacts is given. Moreover

detailed analysis is made of the forming mechanism of residual stress in the surface layer of arc erosion hollow. A physical model is established on this residual stress distribution. The calculating method is given on the length of the residual pulling stress zone in the surface layer of arc erosion hollow.