Digital Computer Calculation of Internal Fault Currents in a Synchronous Machine

A synchronous machine with a fault in its armature winding may be represented by an equivalent circuit in three symmetrical components. The line and neutral terminals of the equivalent circuit are connected to a system network in each sequence. The fault point of the positive sequence is connected to the neutral of the negative sequence, and so forth, representing a single phase- to-ground, or turn-to-turn, fault. Electromotive forces behind the corresponding reactance are introduced in every branch of the positive-sequence network of the faulty machine and an equivalent electromotive force of the system is considered. The resulting network consists of three loops with four electromotive forces. The calculation of the current flow in this network is programmed for solution on the IBM-7090 digital computer.