Abstract
We used the Method of Moments (MoM), which is a numerical electromagnetic field computation method, to study the surge characteristics of twisted pair single phase electric power lines. The result shows that wires stranded less than with several turns/m have almost same surge characteristics as parallel lines, but the surge impedance decreases in tens of % when the number of the strands increases. To verify the simulation results, we measured the surge characteristics of a model line of twisted pair experimentally, and there is good accordance between them. It is possible to simulate the surge in twisted pair covered with polymer dielectric insulators by MoM.
Moreover, we studied the surge characteristics of twisted pair which is inserted into a metallic tube. According to the result, the effect of the strand is smaller than that in free space without the metallic pipe. There are two propagation modes in common mode that are fast surge and slow one. Few influences of the number of the strands on the surge velocity occur in the fast propagation surge, but the increase of the surge impedance and the slow down of the propagation speed are caused by twining in the slow propagation mode.
