(i) Static Relays: Introduction to static relays, merits and demerits.
Comparators: amplitude and phase comparators, duality between amplitude and phase
comparators. Introduction to (a) amplitude comparators-circulating current type, phase
splitting type and sampling type, (b) phase comparators-vector product type and
coincidence type.
(ii) Static over Current Relays: Introduction to instantaneous, definite time, inverse
time and directional overcurrent relays.
Units: II
(i) Static Differential Relays: Brief description of static differential relay
schemes-single phase and three phase schemes. Introduction to static differential
protection of generator and transformer.
(ii) Static Distance Relays: Introduction to static impedance, reactance and mho relays.
Units: III
(i) Carrier Current Protection: Basic apparatus and scheme of power line
carrier system. Principle of operation of directional comparison and phase comparison
carrier protection and,carrier assisted distance protection.
(ii) Distance Protection: Effect of power swings on the performance of distance
protection. Out of step tripping and blocking relays, mho relay with blinders. Introduction to
quadrilateral and elliptical relays.
Units: IV
Circuit Breakers I: Electric arc and its characteristics, arc interruption-high
resistance interruption and current zero interruption. Arc interruption theories-recovery rate
theory and energy balance theory. Restriking voltage and recovery voltage, develop
expressions for restriking voltage and RRRV. Resistance switching, current chopping and
interruption of capacitive current. Oil circuit breakers-bulk oil and minimum oil circuit
breakers. Air circuit breakers.
Units: V
(i) Circuit Breakers II: Air blast, SF6 and vacuum circuit breakers. Selection of
circuit breakers, rating of circuit breakers.
(ii) Digital Protection: Introduction to digital protection. Brief description of block
diagram of digital relay. Introduction to digital overcurrent, transformer differential and
transmission line distance protection.