ABSTRACT

Symmetrical components were introduced in 1918 by C. L. Fortescue as an analytical tool for analyzing the operation of three-phase electric machines under unbalanced operating conditions. One of the main applications of symmetrical components is in analyzing unbalanced faults on three- phase a.c. networks. In the terminology of matrix theory, the symmetrical components of voltages and currents are obtained by a linear transformation from phase quantities, and the main benefit of symmetrical component analysis derives from the fact that the symmetrical component transformation matrix is made up of eigenvectors of the impedance matrix of a balanced three- phase power apparatus. Faults on a power network occur due to equipment failure or other natural catastrophes, such as tornadoes, fires, and floods. Although a fault may create an open circuit in the network, the short circuit is the fault which causes the greatest concern. The other likely short circuits are three-phase, phase-to-phase, or phase-to-phase-to ground.