Switchgear and Protection

Miniature circuit breaker (MCB); elementary principles of arc interruption; Restriking and recovery voltages; restriking phenomenon; RRRV (average and maximum); Current chopping and resistance switching; Oil, air blast, vacuum and SF6 circuit breakers; ratings and specifications; auto-reclosing

Relay connection; balanced beam attracted armature relay; induction disc and cup relays; torque equation; Relay classification: instantaneous, DMT and IDMT types; Overcurrent, undervoltage, directional, differential and percentage differential relays; universal torque equation; Distance relays: impedance, reactance, mho and offset mho; characteristics and comparison

Generator protection against stator faults, rotor faults and abnormal conditions; Restricted earth fault and inter-turn fault protection; Transformer percentage differential protection; design of CT ratio; Buchholz relay protection; numerical examples

Overcurrent protection schemes; PSM and TMS; numerical examples; Carrier current and three-zone distance relay using impedance relays; Busbar protection using differential protection; Static relays: classification and basic components

Generation of overvoltages in power systems; protection against lightning overvoltages; Valve type and zinc oxide lightning arresters; Grounded and ungrounded neutral systems; effects of ungrounded neutral; Methods of neutral grounding: solid, resistance, reactance; arcing grounds and grounding practices