Verify Account

SYLLABUS

UNIT-I

RELAYS Electromagnetic relays – Basic requirements of relays – Primary and backup protection – Construction details of – Attracted armature, Balanced beam, Inductor type and differential relays – Universal torque equation – Characteristics of over current, Direction and distance relays, Static relays – Advantages and disadvantages – Definite time, Inverse and IDMT static relays – Comparators – Amplitude and phase comparators. Microprocessor based relays – Advantages and disadvantages – Block diagram for over current (Definite, Inverse and IDMT) and Distance relays and their flowcharts.

UNIT-II

PROTECTION OF GENERATORS AND TRANSFORMERS Protection of generators against stator faults, Rotor faults and abnormal conditions. Restricted earth fault and inter-turn fault protection. Numerical problems on percentage winding unprotected. Protection of transformers: Percentage differential protection, Numerical problem on design of CT ratio, Buchholz relay protection, Numerical Problems.

UNIT-III

PROTECTION OF FEEDERS AND LINES Protection of feeder (Radial and ring main) using over current relays. Protection of transmission line – 3 zone protection using distance relays. Carrier current protection. Protection of bus bars.

UNIT-IV

CIRCUIT BREAKERS Circuit breakers: Elementary principles of arc interruption, Recovery, Restriking voltage and recovery voltage – Restriking phenomenon, Average and max. RRRV, Numerical problems – Current chopping and resistance switching – CB ratings and specifications: Types and numerical problems – Auto reclosures, Description and operation of following types of circuit breakers: Minimum oil circuit breakers, Air blast circuit breakers, Vacuum and SF6 circuit breakers.

UNIT-V

OVER VOLTAGES IN POWER SYSTEMS Generation of over voltages in power systems – Protection against lightning over voltages – Valve type and Zinc-Oxide lightning arresters – Insulation coordination – BIL.