Power system constitute a major part of the electrical system relating in the present world. Every single portion of this system assumes a major part in the accessibility of the electrical power one uses at their homes, enterprises, workplaces, industrial facilities and so on. Any deficiency in power system causes a ton of inconvenience for the maintenance of the system. So transmission system needs a proper protection scheme to ensure continuous power supply to the consumers. The countless extent of power systems and applications requires the improvement in suitable techniques for the fault classification in power transmission systems, to increase the efficiency of the systems and to avoid major damages. For this purpose, the technical literature proposes a large number of methods. This chapter analyzes the technical literature, summarizing the most important methods that can be applied to fault classification and advanced technologies developed by various researchers in power transmission systems.