Surface flashover

There is no subject which is so fraught with empiricism as surface flashover. A tremendous amount of work has been done on the subject of breakdown in gases, solids and liquids, but practically all of it is for uniform fields in isotropic systems. When we mix a solid with a gas or a liquid so that the field is not uniform, the amount of surface, the condition of the surface and the disposition of the surface between electrodes are only a few of the variables which complicate the surface flashover problem. In addition to these, we have the geometry of the interface (method of attachment of electrodes), the relative dielectric constants of the two phases (gas and solid) and the electric strength of the gas. Moreover, the nature of the voltage applied (that is its wave shape and time duration) as well as the available power also have large effects.