Transient pilot-cable induction from underground power-transmission systems

The paper considers transient induction from an undergound power circuit into an adjacent pilot cable. Results, in the form of transient waveshapes, are given for a number of representative cases in response to step-type energisation of one of the power cables. The results show that dangerous transient overvoltages may arise in the case of relatively long systems. The paper then compares various design measures aimed at reducing prospective overvoltages. The given analytical results were obtained by applying numerical Laplace transform methods, and multiconductor transmission line theory, to a mathematical model which takes realistic account of such factors as skin effect in the conductors and of mutual coupling between cables due to current penetration into the soil.