Switchgear and Protection (EE422)


B.Tech (E&E)




Programme Specific Electives (PSE)

Credits (L-T-P): 

04 (3-1-0)


Fuses and  switches,  methods of earthing,  Circuit Breakers: Arcs, Interruption, RRRV, Current chopping, Interruption of capacitive current, Resistance switching. Types of circuit breakers, Circuit breaker ratings, Auto reclosure. Protective relaying: Functions, Standard definitions and terminology, Fundamental characteristics. Relay classifications, Electromechanical relays. Directional relay, Reverse power relay. Differential protection schemes for bus-bars, transformers and alternators. Frame leakage, bus-bar and transformer protection. Buchholtz relay, Backup protection.  Alternator protection: Negative phase sequence relay, Loss of field protection. Line protection: Overcurrent relays and  schemes,  Distance relays and schemes, Effect of arc resistance, Translay relaying, Carrier current relaying. Induction motor protection: Abnormal operating conditions, Undervoltage,  Phase and earth fault, Overload and unbalance voltage protection.  Solid state relays: Comparators,  Duality between phase and amplitude comparators. General equation of comparators, Realization of directional, Ohm, reactance, impedance and Mho characteristics using the general characteristic equation,  Static distance relays. Computer aided relaying: Introduction to microcomputer based relays,  General functional diagram of microcomputer-based relays.


1. Ravindranath, Chander , Power System Protection and Switchgear, Wiley Eastern, 1994.
2. C. L. Wadhwa, Electrical Power Systems, 2nd Edition, PHI, 1993.
3. Arun G. Phadke, S H Horowitz, Power System Relaying, 2nd Edition, John Wiley, 1995.
4. Badriram, D. N. Vishwakarma, Power System Protection and Switchgear, TMH, 1995.


Electrical and Electronics Engineering

Contact us

Shubhanga K N

Professor and Head of the Department

Department of Electrical and Electronics Engineering
National Institute of Technology Karnataka, Surathkal
Srinivasnagar, Surathkal, Mangalore-575025. Karnataka, India.
Ph : +91-824-2473045
Fax: +91-824-2474039
E-mail: ee_hod[AT]nitk[DOT]edu[DOT]in