Analysis of electromagnetic field transient on branch feeders by numerical electromagnetic field computation

This paper presents the fundamental surge phenomenon when a step voltage is applied to a horizontal line above the ground that has two branch feeders. The authors studied line currents and voltages at a joint with the moment method that calculates electromagnetic field in the frequency domain. The reflected current from the joint shows inductive characteristic or capacitive one depending on the angle between the main line and branch feeders, which varies gradually and not stepwise in their numerical analysis considering transverse magnetic mode. The electromagnetic coupling between the main line and branch feeders causes these phenomena. In addition to the computer simulations, they measured the currents in the miniaturized model and the results make the validity of their analysis clear about changes of the reflected current depending on the angle.