Course

Unit 1

Nature, causes and consequences of faults – Fault statistics – Need for protection – Essential qualities of protection – Types of protection – Primary and back up protection – Instrument Transformers – Basics of switchgear – Fuses, isolators, Earthing switches.

Development of protective relays – Recent developments – Operating principle – Classification of relays based on construction – Electromagnetic relays, Thermal relays, Overview of Static and Microprocessor relays, Numerical Relays – Introduction, Block diagram, Sampling theorem, Anti–Aliasing Filter, Least square method for estimation of phasor, concept of Discrete Fourier Transform to estimate the phasor.

Unit 2

Apparatus protection – Bus Bar protection, Transmission Line protection – realization of distance relays using numerical relaying algorithm, Introduction to wide area measurement (WAM) system – Generator protection – Motor Protection – Transformer Protection.

Overvoltage protection – Lightning arresters – Operating principle and types of arresters, Surge absorbers – Insulation co-ordination.

Unit 3

Circuit breakers – Operating principle – Arc phenomenon, principle, DC and AC Circuit Breaking – Problems of circuit interruption – Interruption of capacitive currents, Current chopping, Resistance Switching and methods of arc extinction – Arc interruption theories – Arc voltage, restriking voltage, Recovery voltage.

Types of circuit breaker – Construction and Operating Principle – HVDC circuit breaker – Selection of circuit breaker and its ratings – Auto reclosing.

• A. S. Ingole, ”Switchgear and protection” Umesh publication, 2006
• B. Ravindranath and M. Chander, ”Power system protection and switchgear”, New age International (P) Ltd., 2003
• C. Christopoulos and A. Wright, ”Electrical power system protection”, Springer International edition, 2010.
• Hadley, et al. Securing Wide Area Measurement Systems, Pacific Northwest National Laboratory. June 2007.