The resistance of breakdown in transformer oil

Abstract

The conditions under which breakdown of composite liquid - solid insulation can be occurred, e.g., in transformer, play an important role in designing of such insulation. The initial state of breakdown development is explained on the basis of bubble theory and formation of a plasma channel between the electrodes. The electrical resistance of plasma channel is calculated using several theories and its changes from a few ohms to a few hundred milliohms due to Joule heating caused by high arc current which flows through the plasma. The dynamics of the arc current depends on the parameters of outer circuit and is represented by RLC circuit.