ABSTRACT
A fault in an electrical power system is the unintentional and undesirable creation of a conducting path or a blockage of current. Power system faults may be categorized as one of four types: single line-to-ground, line-to-line, double line-to-ground and balanced three-phase. The method of symmetrical components is particularly suited to fault analysis. The general terminals brought out are for purposes of external connections that will simulate faults. All rotating machines are capable of contributing to fault current, at least momentarily. Synchronous and induction motors will continue to rotate due to inertia and function as sources of fault current. The load currents and fault currents are out of phase with each other, making their sum more nearly equal to the larger components than would have been the case if the currents were in phase. The basic reason for making fault studies is to provide data that can be used to size and set protective devices.
