Calculation of Internal Fault Currents in Synchronous Machines

An internal fault in the armature winding of a synchronous machine occurs at the breakdown of either the minor insulation (turn-to-turn fault) or the major insulation (phase-to-ground fault). The faulty synchronous machine is represented by an equivalent circuit in three symmetrical components which can be connected to the corresponding network. The fault currents can be calculated from the obtained equivalent network. The calculation of internal fault currents has been programmed for the IBM 7090 digital computer, and the calculated values have been compared with the experimental results.