Calculation of Ground Fault Currents Using an Equivalent Circuit and a Simplified Ladder Network

A three-terminal equivalent circuit is developed for a given power line with multiple grounds so that the phase current can be readily computed for a variety of fault conditions. The three terminals of the circuit are phase, neutral, and remote earth. A procedure is described here for computing the current distribution along the grounded conductor of the line from the phase current. All computations are restricted to a ladder network that does not include internal sources or mutually-coupled elements. No limitations are placed on the parameters of the power line. The equivalent circuit can also be used to represent the effect of the faulted power line upon a separate system bonded to the grounded conductor, such as a communication cable.