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EPEG 415

EPEG 415                               SWITCHGEAR AND PROTECTION                        3 Credits

Objective: To present information on the techniques and hardware used for power system protection.


Introduction: Principles of power system protection; System Vs apparatus protection; analog vs. digital protection; Protection system components: potential / current transformers, fuses, circuit, breaker, isolator; Computerized status monitoring; Zone protection, back up schemes, coordination, and effect of fault impedance.

Fuses: Use, performance, selection of fuse material, types of fuses, main features of HRC fuses, selection and co-ordination of fuses

Reactors: Purpose and construction of various types of reactors, location of reactors, selection of reactors

Protective Relays: Concept of electromechanical, static and digital relaying, type and classification of relay, differential and percentage differential relay, impedance, admittance, reactance relays distance protection concept, carrier and pilot wire systems, digital vs. analog protection systems; Significance of computerized protection systems; Microprocessor controlled relaying system.

Power Circuit Breakers: Arc characteristics, arc interruption, arc gaps, short circuit KVA calculations, percentage method, types of circuit breakers: air, oil, vacuum, SF6; Automatic circuit, reclosers

Apparatus Protection: Generator, transformer, transmission lines protection systems

Protection Against Lightning and Insulation Co-ordination: Lightning wave shape of lightning stroke, classification of direct lightning discharges, over voltage due to lightning stroke, protection against lightning, lightning arrestors, protection from surge waves


  1. Sunil S. Rao, Switch gear and protection
  2. Elgerd, Electrical Energy System Theory, McGraw
  3. Stevenson, Elements of Power System Analysis, McGraw Hill
  4. Guile and Paterson, Electric Power System Vol. I and II, John Wiley
  5. T.S. Mathava Rao, Power system Protection with micro-processor application
  6. Patra, Basti, and S Chouthuria, Power system Protection

Course of Study

Course of Study

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