Experimental Analysis on Nonlinear Conducting Impedance of Steel Conductors

In this paper, the nonlinear conducting impedance characteristics of galvanized steel conductors are studied by an experimental system for amplitude modulated impedance measurement. Three flat steel conductors and three round steel conductors were tested under 50Hz AC current ranging from 0 to 300A. The main findings show that the impedance amplitude, real part and imaginary part of both flat and round steel conductors show nonlinear behavior: they increase rapidly to a peak value (e.g., Flat Steel 1#: <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{5.1}\mathbf{m}\mathbf{\Omega}$</tex> at a current of about 50A) and then gradually decrease. The impedance of flat steel conductors is inversely proportional to the cross-sectional area, while the round steel conductors show a clear crossover behavior. The impedance angles vary greatly and also show a slightly complex variation behavior.