JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

UNIT - I

Protection System: Importance of protective relaying in power systems; Fundamental requirements of a good protection scheme; Zones of protection, Primary and Back–up Relaying. Protective Relays: Terms used in protective relaying; Classifications of Relays – Constructional, Functional; Electromagnetic Relays – attracted armature, induction disc, induction cup types relays

UNIT - II

Over current and Earth fault relays, Directional, Differential, Distance Relays etc.; Principles & Characteristics of relays; Operation, setting, testing and applications, maintenance requirements of relays; Translay relay; Negative Sequence relays; Universal Relay Torque Equation; Electronic relays; Static relays; Digital relays; Microprocessor and PC based relaying; Current & Future trends.

UNIT - III

Switchgear Circuit Interruption : Fuses - Types of fuses, Terms (Fusing factor, Breaking capacity etc.), Fuse selection, HRC fuses and their applications; Arcing phenomena, Essential properties of arc, Initiation and Maintenance of an arc, Arc voltage, Arc interruption theories, Recovery and Restriking voltages, Rate of Rise of Restriking Voltage (RRRV), Resistance Switching, Inductive current chopping, Capacitive current breaking. Circuit Breakers : AC and DC circuit breaking, Types of Circuit Breakers - ACB, OCB, ABCB, SF6CB, VCB; Static Circuit Breakers; Comparative merits and demerits of different types of CBs, Rating of Circuit Breakers, Testing and Selection of Circuit Breakers, Auto reclosing.

UNIT - IV

Power Plant Protection: Protection Schemes: Schemes for protection of transmission line; Merz-Price circulating current scheme, Percentage differential relay, Restricted earth fault protection, Negative Sequence protection, Translay scheme, Carrier relaying scheme, Pilot relaying scheme, Static and other relays used in transmission line protection. Generator Protection: Neutral earthing, stator and rotor earth faults, sustained external faults, instability, protective systems. Transformer Protection: Various transformer protections, protective systems for Generator Transformers (GTs), Unit Auxiliary Transformers (UATs) and Station Transformers (STs).

UNIT - V

Motor Protection: Faults and Protection systems. Busbar Protection: Continuity of supply, Discrimination, Circulating current systems, special features relating to different voltage systems. Feeder Protection: Continuity of supply discrimination, outline of protection systems – Pilot wire, carrier current, distance protection, PLCC – Telemetry Communication.

REFERENCE:

• 1. The Electricity Council: Power System Protection/ Vol.1, 2 & 3/Peter Peregrinus Ltd./1990.
• 2. Protective Relays: Their Theory and Practice/ Vol. 1 & 2/ Van, A. R., & Warrington, C / Chapman and Hall, 1969.
• 3. Transmission Network Protection: Theory and Practice/ Paithankar, Y. G./ Marcel Dekker, Inc./1998.
• 4. Power System Protection and Switchgear/ B. Ravindranath and M. Chander/Wiley Eastern Ltd. M. Tech – I Year – II Sem. (Energy Systems)