About the Failure of Closed Heavy Current Contact Pieces in Insulating Oil at High Temperature

The failure of closed contacts in insulating oil of elevated temperature was attributed hitherto to the formation of oil carbon in the contact interface. However, experiments have shown the formation of surface films before the development of oil carbon. Under the assumption that the reduction of the conducting area is following the experimentally determined film growth, it is possible to estimate contact life in dependence of various parameters using the characteristic values of the contact interface.