Analysis of Faults in an Electric Power System

Electrical fault is an abnormal condition, caused by equipment failure, human errors and environmental conditions. These faults cause interruption to electric current flows, equipment damages and even death of humans, birds and animals. For example, a short circuit is a fault in which current bypasses the normal load. An open circuit fault occurs if a circuit is interrupted by some failures. In three phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a ground fault or earth fault, current flows into the earth. When fault occurs currents deviate from normal value. Bus impedance matrices are useful in the determination of these currents. This paper shows the analyses of a faulted power system using bus impedance matrices. The magnitudes of the currents during various fault conditions were determined for a particular power network. The results obtained show that the three-phase fault (symmetrical fault) has the highest fault current. These results enable the proper specification and optimal placing of circuit breakers for protection of the network.