Department of Electrical and Electronics Engineering
Power System Protection
Unit - 1
Types of transformers Phasor diagram for a three Phase transformer-Equivalentcircuit of transformer Types of faults in transformers- Over current protectionPercentage Differential Protection of Transformers -Inrush phenomenon-Highresistance Ground Faults in Transformers - Inter-turn faults in transformers - Incipientfaults in transformers - Phenomenon of over-fluxing in transformers - Transformerprotection application chart .Electrical circuit of the generator Various faults andabnormal operating conditions-rotor fault Abnormal operating conditions; numericalexamples for typical transformer and generator protection schemes
Unit - 2
OVER CURRENT PROTECTION
Time Current characteristics-Current setting Time setting-Over current protectiveschemes - Reverse power or directional relay - Protection of parallel feeders -Protection of ring feeders - Earth fault and phase fault protection - Combined Earthfault and phase fault protection scheme - Phase fault protective scheme directionalearth fault relay - Static over current relays; numerical example for a radial feeder
Unit - 3
DISTANCE AND CARRIER PROTECTION OF TRANSMISSION LINES
Braw back of over Current protection Introduction to distance relay Simpleimpedance relay Reactance relay mho relays comparison of distance relay Distance protection of a three Phase line-reasons for inaccuracy of distance relayreach - Three stepped distance protection - Trip contact configuration for the three -Stepped distance protection - Three-stepped protection of three-phase line against allten shunt faults - Impedance seen from relay side - Three-stepped protection ofdouble end fed lines-need for carrier Aided protection Various options for a carrierCoupling and trapping the carrier into the desired line section - Unit type carrier aideddirectional comparison relaying Carrier aided distance schemes for acceleration ofzone ??.; numerical example for a typical distance protection scheme for a transmissionline.
Unit - 4
BUSBAR R PROTECTION
Introduction Differential protection of busbars-external and internal fault - Actualbehaviors of a protective CT - Circuit model of a saturated CT - External fault with oneCT saturation :need for high impedance Minimum internal fault that can be detectedby the high Stability ratio of high impedance busbar differential scheme -Supervisory relay-protection of three Phase busbars-Numerical examples on designof high impedance busbar differential scheme.
Unit - 5
Introduction Block diagram of numerical relay - Sampling theorem- Correlation witha reference wave Least error squared (LES) technique - Digital filtering-numericalover - Current protection Numerical transformer differential protection-Numericaldistance protection of transmission line