Engineering problems of surface flashover

When an item of high-voltage equipment is insulated with a fluid-whether it is oil, air, sulphur hexafluoride or indeed vacuum-the conductors must be held in position by solid insulating supports. The design of these supports has always been a challenge, because unless great care is taken, the solid/fluid interface can flashover at voltages below those which would cause failure in either the solid or fluid alone. The author describes the two main types of surface flashover along with their associated engineering problems