ANALYSIS OF IMPULSE OVERVOLTAGES I N ELCTRICAL MACHINES BY EMTP

Any turn of windings have leakage mutual indactance with other turns and of course have capacitance with earth and other turns. If a surge comes to the winding, because of the capcitances and indactances, a seris of travelling waves produces that propagate in it by diffrent velocity. Since we can analysis surge overvoltages and voltage among the electrical machines stator windings by travelling waves theory. In this paper by travelling theory we present a model of machine windings, which that the turns of the coil, get as transmission lines systems but these lines are not in homogenouse regions, a part of turns are in slot of core and other parts are in the air. This model analysed by Electro Magnetic Transient Program (EMTP)and then best control method of the impulse over voltages is presented.