Surge propagation in three-phase pipe-type cables, part I ߞUnsaturated pipe

The step response of three-phase pipe-type cable is determined. The solution techniques are closed form and analogous to those developed by Carson for overhead transmission lines. Results are shown for cradled and triangular configurations. The Fast Fourier Transform is used for calculation, dramatically reducing computation time. Delay of the zero sequence wave and attenuation of all components are shown. Calculations neglect saturation of the pipe wall, which follows in a later paper. The results can be incorporated into existing digital transients programs or be used to construct complex frequency-dependent analog models for Transient Network Analyzer (TNA)Studies.