ABSTRACT
Power system design and operation aim to generate and supply power to consumers with reliability, economy and safety. The electric power system included many diverse items of equipment (generation, transmission/distribution and consumer loads) that are costly. The complete power system hence represents a very large capital investment. However, no matter how well a power system is designed, faults from various causes will always occur on a power system. The destructive power of a fault carrying a high current is great and can cause damage to a plant if the fault continues for more than a few seconds, and it may pose a danger to personnel and the public. The provision of adequate protection to detect and disconnect elements of the power system in the event of faults is therefore an integral part of power system design. It is essential to determine the magnitude of fault currents that flow when faults of various types occur in order to facilitate the specification of the type and current settings of the protection to be used and the current ratings of other protective devices, such as fuses, circuit breakers, and current transformers. Network reduction and bus impedance matrix methods for the calculation of different types of faults are discussed in this chapter, including application of the concept of symmetrical components for the analysis of unbalanced faults. Detailed solved examples are provided to enhance students understanding of the various methods of fault analysis.
