Circuit Breakers : Arc voltage, Arc interruption, restriking voltage and recovery voltage, resistance switching, current chopping interruption of capacitive current. Classification of CBs, Air blast CBs. Air break CBs. SF6 CBs, Vacuum CBs, operating mechanism, selection of CBs , HVDC CBs, rating of CBs, testing of CBs. Fuses : Introduction, definition, characteristics, types, applications, selection discrimination. Introduction to protection, protection system and its attributes, sensitivity, selectivity, speed reliability and dependability, system transducers CTs, PTs etc, principles of power system protection. Thermal relay, over current relay, directional over current relay, characteristics and application for protection of transmission lines and feeders. Differential protection-basic principles, zone of protection, percentage differential relay, earth leakage protection, bus bar protection.Distance protection of transmission lines-impedance relay, reactance relay, mho relay, protection of a 3-phase line. Generator protection-protection against stator and rotor faults and abnormal operating conditions (such as unbalanced loading, loss of excitation, over speeding)Induction motor protection, protection against electrical faults (such as phase fault, ground fault) and abnormal operating conditions (such as single phasing, phase reversal overload.) Transformer protection-types of faults, overcorrect protection, differential protection, differential relay with harmonic restraint, protection against high resistance ground faults, interturn faults, Buchholz relay.Introduction to carrier aided protection, numerical protection.