for the protection of power system and its components 1
TRANSCRIPT
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PROTECTION & SWITCHGEARFor the Protection of Power System and its Components
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FAULTS IN POWER SYSTEM:
Definition : ? Over voltage/Under voltage Over current
Over load, short circuit, Over frequency/Under frequency Phase imbalance/ Single phasing/
Sometimes opens in the circuit Mechanical faults
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PROTECTION ZONES:
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PROTECTION ZONES:
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TYPES OF PROTECTION
Human Earthing
Equipment Different Protection schemes
Unit protection and Non-unit protection
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CLASSIFICATION OF PROTECTION SCHEMES:
In unit type Differential Protection Carrier aided protection,
Non-unit type Over current, over/under voltage,
over/under frequency, distance protection
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WORKING PRINCIPLE OF PSP:
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THE PROTECTION TEAM:
Relays Electrical
Electromagnetic Static Numerical
Mechanical Pressure (Buchholz) Flow Thermal
Circuit Breaker (CB) Air break CB, MCB
(3.6 -12kV, 500 MVA) Bulk oil CB
(Upto 36 kV) Minimum Oil CB
(3.6 – 245 kV) Air blast CB
(145 – 1100 kV, 60 GVA) SF6 CB
(3.6 – 800 kV, 50 GVA Vacuum CB
(3.6 – 36 kV, 2 GVA) Solid state CB
Instrument Transformer
DC batteries
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ELECTRICAL RELAYS:
According to characteristic quantities and application can be classified as:
Over-Voltage, Over-Current, Over-Frequency Under-Voltage, Under-Frequency Directional Power Relay Differential Relay, Distance Relay
Reactance Relay, Impedance Relay, Mho Relay, offset Mho relay, Quadrilateral Relay
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UNIT PROTECTION SCHEMES:
Generator protection Motor protection Transformer protection
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GENERATOR PROTECTION
Generator Faults Stator winding faults
(phase to earth, phase to phase, inter-turn) Rotor circuit faults
Conductor to earth, inter-turn fault, rotor open circuit, loss of excitation, unbalance stator current
Abnormal operating condition Failure of prime mover, field failure, unbalance
loading, over voltage at generator terminal, over loading, over speed, ventilation failure
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GENERATOR PROTECTION
STATOR PROTECTION ROTOR FAULT PROTECTION
Differential protection(Merz-Price protection)(Biased differential protection)
Stator Inter-turn prot. Balanced earth fault
prot Stator over heating
prot. Negative sequence prot. Protection against
motoring
Rotor earth fault prot. Loss of Excitation prot. Auto. Field suppression Rotor overheating Rotor temp. alarm Vibration Protection Bearing overheating Over speed protection
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A.C. MOTOR PROTECTION
FAULTS : PROTECTION:
Phase to phase Phase to earth Inter-turn Prolonged overloading Stalling Unbalanced supply
voltage Single phasing Under voltage Reverse phase Loss of synchronism
Stator Over current Stator over heating Rotor over heating Under voltage Unbalanced and single
phasing Reverse phase Ammortisseur over
heating Loss of excitation Loss of synchronism Field winding over heating
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TRANSFORMER PROTECTION:
Buchholz protection Core balance leakage protection Combined leakage and overload protection Differential protection (Biased) Harmonic restraint relay Magnetic balance protection Restricted earth fault Frame leakage protection Generator transformer unit protection
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LINE & FEEDER PROTECTION
Over current and earth fault protection Time graded protection for
Radial, parallel and ring main feeder using directional power relay
Current graded protection Differential pilot wire protection Carrier current protection Distance protection
Impedance relay, reactance relay, Mho relay, offset Mho relay, quadrilateral relay,
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DEFINITE TIME OVER CURRENT (50) & INVERSE TIME OVER CURRENT (51)Basic protection principle
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OVER VOLTAGE (59) & UNDER VOLTAGE (27)
Basic protection principle
VOLTAGE BALANCE (DIFFERENTIAL)Basic protection principle
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DISTANCE RELAYINGBasic protection principle
Uses both current and voltage to determine the zone of the faultBased on KVLThree phase system loops, RY,YB,BR, RG, YG, BGPhase comparator principlePhase and ground faults
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DISTANCE RELAYING
S1 = IR ZR – VR
S2 = VR
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DISTANCE RELAYING
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DIFFERENTIAL PROTECTIONBasic protection principle
Based on KCL Used for protection of Generator, Motor, Transformer, Busbar, Transmission line, Reactor
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BUSBAR & TRANSFORMER DIFFERENTIAL PROTECTION
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LINE DIFFERENTIAL PROTECTION
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DEVICE NUMBER IDENTIFICATION
21 Z1 – Z4 : phase distance relay for zone 1 to 421N z1 – Z4 : ground distance relays for zone 1 to 450H : high set instantaneous over current relay50 : instantaneous over current relay62 : time delay for tripping67N : directional relay in neutralSER/DFR : sequence of event recorder/ digital fault recorder
List box method and fill box method
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OTHERS:
Bus bar protection Protection against over voltage due to
lightning using LA Insulation coordination Earthing Travelling wave ralays
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THANK YOU