book

Protective Relaying, 4th Edition

by J. Lewis Blackburn, Thomas J. Domin

February 2014

Intermediate to advanced

695 pages

21h 31m

English

CRC Press

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Preface to the Fourth Edition
Preface to the Third Edition
Preface to the Second Edition
Preface to the First Edition
Author
Chapter 1 - Introduction and General Philosophies
1.1 Introduction and Definitions1.2 Typical Protective Relays and Relay Systems1.3 Typical Power Circuit Breakers1.4 Nomenclature and Device Numbers1.5 Typical Relay and Circuit Breaker Connections1.6 Basic Objectives of System Protection1.6.1 Reliability1.6.2 Selectivity1.6.3 Speed1.6.4 Simplicity1.6.5 Economics1.6.6 General Summary1.7 Factors Affecting the Protection System1.7.1 Economics1.7.2 Personality Factor1.7.3 Location of Disconnecting and Input Devices1.7.4 Available Fault Indicators1.8 Classification of Relays1.8.1 Protective Relays1.8.2 Regulating Relays1.8.3 Reclosing, Synchronism Check, and Synchronizing Relays1.8.4 Monitoring Relays1.8.5 Auxiliary Relays1.8.6 Other Relay Classifications1.9 Protective Relay Performance1.9.1 Correct Operation1.9.2 Incorrect Operation1.9.3 No Conclusion1.9.4 Tracking Relay Performance1.10 Principles of Relay Application1.11 Information for Application1.11.1 System Configuration1.11.2 Impedance and Connection of the Power Equipment, System Frequency, System Voltage, and System Phase Sequence1.11.3 Existing Protection and Problems1.11.4 Operating Procedures and Practices1.11.5 Importance of the System Equipment Being Protected1.11.6 System Fault Study1.11.7 Maximum Loads and System Swing Limits1.11.8 Current and Voltage Transformer Locations, Connections, and Ratios1.11.9 Future Expansion1.12 Structural Changes within the Electric Power Industry1.13 Reliability and Protection Standards1.13.1 Regulatory AgenciesBibliography
Chapter 2 - Fundamental Units: Per-Unit and Percent Values
2.1 Introduction2.2 Per-Unit and Percent Definitions2.3 Advantages of Per Unit and Percent2.4 General Relations between Circuit Quantities2.5 Base Quantities2.6 Per-Unit and Percent Impedance Relations2.7 Per-Unit and Percent Impedances of Transformer Units2.7.1 Transformer Bank Example2.8 Per-Unit and Percent Impedances of Generators2.9 Per-Unit and Percent Impedances of Overhead Lines2.10 Changing Per-Unit (Percent) Quantities to Different Bases2.10.1 Example: Base Conversion with Equation 2.342.10.2 Example: Base Conversion Requiring Equation 2.33Bibliography
Chapter 3 - Phasors and Polarity
3.1 Introduction3.2 Phasors3.2.1 Phasor Representation3.2.2 Phasor Diagrams for Sinusoidal Quantities3.2.3 Combining Phasors3.2.4 Phasor Diagrams Require a Circuit Diagram3.2.5 Nomenclature for Current and Voltage3.2.5.1 Current and Flux3.2.5.2 Voltage3.2.6 Phasor Diagram3.3 Circuit and Phasor Diagrams for a Balanced Three-Phase Power System3.4 Phasor and Phase Rotation3.5 Polarity3.5.1 Transformer Polarity3.5.2 Relay Polarity3.6 Application of Polarity for Phase-Fault Directional Sensing3.6.1 90°–60° Connection for Phase-Fault Protection3.7 Directional Sensing for Ground Faults: Voltage Polarization3.8 Directional Sensing for Ground Faults: Current Polarization3.9 Other Directional-Sensing Connections3.10 Application Aspects of Directional Relaying3.11 Summary
Chapter 4 - Symmetrical Components: A Review
4.1 Introduction and Background4.2 Positive-Sequence Set4.3 Nomenclature Convenience4.4 Negative-Sequence Set4.5 Zero-Sequence Set4.6 General Equations4.7 Sequence Independence4.8 Positive-Sequence Sources4.9 Sequence Networks4.9.1 Positive-Sequence Network4.9.2 Negative-Sequence Network4.9.3 Zero-Sequence Network4.9.4 Sequence Network Reduction4.10 Shunt Unbalance Sequence Network Interconnections4.10.1 Fault Impedance4.10.2 Substation and Tower-Footing Impedance4.10.3 Sequence Interconnections for Three-Phase Faults4.10.4 Sequence Interconnections for Single-Phase-to-Ground Faults4.10.5 Sequence Interconnections for Phase-to-Phase Faults4.10.6 Sequence Interconnections for Double-Phase-to-Ground Faults4.10.7 Other Sequence Interconnections for Shunt System Conditions4.11 Example: Fault Calculations on a Typical System Shown in Figure 4.164.11.1 Three-Phase Fault at Bus G4.11.2 Single-Phase-to-Ground Fault at Bus G4.12 Example: Fault Calculation for Autotransformers4.12.1 Single-Phase-to-Ground Fault at H Calculation4.13 Example: Open-Phase Conductor4.14 Example: Open-Phase Falling to Ground on One Side4.15 Series and Simultaneous Unbalances4.16 Overview4.16.1 Voltage and Current Phasors for Shunt Faults4.16.2 System Voltage Profiles during Faults4.16.3 Unbalanced Currents in the Unfaulted Phases for Phase-to-Ground Faults in Loop Systems4.16.4 Voltage and Current Fault Phasors for All Combinations of the Different Faults4.17 SummaryBibliographyAppendix 4.1 Short-Circuit MVA and Equivalent ImpedanceA.4.1-1 Three-Phase FaultsA.4.1-2 Single-Phase-to-Ground FaultsAppendix 4.2 Impedance and Sequence Connections for Transformer BanksA.4.2-1 Two-Winding Transformer BanksA.4.2-2 Three-Winding and Autotransformer BanksAppendix 4.3 Sequence Phase Shifts through Wye–Delta Transformer BanksA.4.3-1 SummaryAppendix 4.4 Impedance of Overhead LinesA.4.4-1 Resistance of Overhead LinesA.4.4-2 Inductive Reactance of a Single Conductor over EarthA.4.4-3 Mutual Inductive Reactance of Two Conductors over EarthA.4.4-4 Impedance of Three-Phase Overhead LinesA.4.4-4.1 Three-Phase Overhead Line: No Ground Wires (Lossless Earth)A.4.4-5 GMR and GMD Concepts: Three-Phase Overhead LinesA.4.4-6 Three-Phase Overhead Line: Impact of Ground Wires and Earth ResistanceAppendix 4.5 Zero-Sequence Impedance of Transformers
Chapter 5 - Relay Input Sources
5.1 Introduction5.2 Equivalent Circuits of Current and Voltage Transformers5.3 CTs for Protection Applications5.4 CT Performance on a Symmetrical AC Component5.4.1 Performance by Classic Analysis5.4.2 Performance by CT Characteristic Curves5.4.3 Performance by ANSI/IEEE Standard Accuracy Classes5.4.4 IEC Standard Accuracy Classes5.5 Secondary Burdens during Faults5.6 CT Selection and Performance Evaluation for Phase Faults5.6.1 CT Ratio Selection for Phase-Connected Equipment5.6.2 Select the Relay Tap for the Phase–Overcurrent Relays5.6.3 Determine the Total Connected Secondary Load (Burden) in Ohms5.6.4 Determine the CT Performance Using the ANSI/IEEE Standard5.6.4.1 When Using a Class T CT5.6.4.2 When Using a Class C CT and Performance by the ANSI/IEEE Standard5.6.4.3 When Using a Class C CT and Performance with the CT Excitation Curves5.7 Performance Evaluation for Ground Relays5.8 Effect of Unenergized CTs on Performance5.9 Flux Summation Current Transformer5.10 Current Transformer Performance on the DC Component5.11 Summary: Current Transformer Performance Evaluation5.11.1 Saturation on Symmetrical AC Current Input Resulting from the CT Characteristics and the Secondary Load5.11.2 Saturation by the DC Offset of the Primary AC Current5.12 Current Transformer Residual Flux and Subsidence Transients5.13 Auxiliary Current Transformers in CT Secondary Circuits5.14 Voltage Transformers for Protective Applications5.15 Optical SensorsBibliography

Chapter 6 - Protection Fundamentals and Basic Design Principles
6.1 Introduction6.2 Differential Principle6.3 Overcurrent–Distance Protection and the Basic Protection Problem6.3.1 Time Solution6.3.2 Communication Solution6.4 Backup Protection: Remote versus Local6.5 Basic Design Principles6.5.1 Time–Overcurrent Relays6.5.2 Instantaneous Current–Voltage Relays6.5.3 Directional-Sensing Power Relays6.5.4 Polar Unit6.5.5 Phase Distance Relays6.5.5.1 Balanced Beam Type: Impedance Characteristic6.5.6 R–X Diagram6.5.7 Mho Characteristic6.5.8 Single-Phase Mho Units6.5.9 Polyphase Mho Units6.5.9.1 Three-Phase Fault Units6.5.9.2 Phase-to-Phase Fault Units6.5.10 Other Mho Units6.5.11 Reactance Units6.6 Ground Distance Relays6.7 Solid-State Microprocessor Relays6.8 SummaryBibliography
Chapter 7 - System-Grounding Principles
7.1 Introduction7.2 Ungrounded Systems7.3 Transient Overvoltages7.4 Grounded-Detection Methods for Ungrounded Systems7.4.1 Three-Voltage Transformers7.4.2 Single-Voltage Transformers7.5 High-Impedance Grounding Systems7.5.1 Resonant Grounding7.5.2 High-Resistance Grounding7.5.3 Example: Typical High-Resistance Neutral Grounding7.5.4 Example: Typical High-Resistance Grounding with Three Distribution Transformers7.6 System Grounding for Mine or Other Hazardous-Type Applications7.7 Low-Impedance Grounding7.7.1 Example: Typical Low-Resistance Neutral Reactor Grounding7.7.2 Example: Typical Low-Resistance Neutral Resistance Grounding7.8 Solid (Effective) Grounding7.8.1 Example: Solid Grounding7.8.2 Ground Detection on Solid-Grounded Systems7.9 Ferroresonance in Three-Phase Power Systems7.9.1 General Summary for Ferroresonance for Distribution Systems7.9.2 Ferroresonance at High Voltages7.10 Safety Grounding7.11 Grounding Summary and RecommendationsBibliography
Chatper 8 - Generator Protection/Intertie Protection for Distributed Generation
8.1 Introduction8.1.1 Historical Perspectives8.1.2 Bulk Power Generators8.1.3 Distributed Generators8.1.4 Potential Problems8.2 Generator Connections and Overview of Typical Protection8.3 Stator Phase-Fault Protection for All Size Generators8.3.1 Differential Protection (87) for Small kVA (MVA) Generators8.3.2 Multi-CT Differential Protection (87) for All Size Generators8.3.3 High-Impedance Voltage Differential Protection for Generators8.3.4 Direct-Connected Generator Current Differential Example8.3.5 Phase Protection for Small Generators That Do Not Use Differentials8.3.6 Unit Generator Current Differential (87) Example for Phase Protection8.4 Unit Transformer Phase-Fault Differential Protection (87TG)8.5 Phase-Fault Backup Protection (51 V) or (21)8.5.1 Voltage-Controlled or Voltage-Restraint Time–Overcurrent (51 V) Backup Protection8.5.2 Phase Distance (21) Backup Protection8.6 Negative-Sequence Current Backup Protection8.7 Stator Ground-Fault Protection8.7.1 Ground-Fault Protection for Single Medium or Small Wye-Connected Generators (Type 1a: See Figure 8.3 and Figure 8.11)8.7.2 Ground-Fault Protection of Multiple Medium or Small Wye- or Delta-Connected Generators (Type 2: See Figure 8.2 and Figure 8.12)8.7.3 Ground-Fault Protection for Ungrounded Generators8.7.4 Ground-Fault Protection for Very Small, Solidly Grounded Generators8.7.5 Ground-Fault Protection for Unit-Connected Generators Using High-Impedance Neutral Grounding (Type 1b: See Figure 8.5)8.7.6 Added Protection for 100% Generator Ground Protection with High-Resistance Grounding8.7.7 High-Voltage Ground-Fault Coupling Can Produce V0 in High-Impedance Grounding Systems8.7.8 Ground-Fault Protection for Multidirect-Connected Generators Using High-Resistance Grounding8.8 Multiple Generator Units Connected Directly to a Transformer: Grounding and Protection8.9 Field Ground Protection (64)8.10 Generator Off-Line Protection8.11 Reduced or Lost Excitation Protection (40)8.11.1 Loss of Excitation Protection with Distance (21) Relays8.11.2 Loss of Excitation Protection with a Var-Type Relay8.12 Generator Protection for System Disturbances and Operational Hazards8.12.1 Loss of Prime Mover: Generator Motoring (32)8.12.2 Overexcitation: Volts per Hertz Protection (24)8.12.3 Inadvertent Energization: Nonsynchronized Connection (67)8.12.4 Breaker Pole Flashover (61)8.12.5 Thermal Overload (49)8.12.6 Off-Frequency Operation8.12.7 Overvoltage8.12.8 Loss of Synchronism: Out-of-Step8.12.9 Subsynchronous Oscillations8.13 Loss of Voltage Transformer Signal8.14 Generator Breaker Failure8.15 Excitation System Protection and Limiters8.15.1 Field Grounds8.15.2 Field Overexcitation8.15.3 Field Underexcitation8.15.4 Practical Considerations8.16 Synchronous Condenser Protection8.17 Generator-Tripping Systems8.18 Station Auxiliary Service System8.19 Distributed Generator Intertie Protection8.19.1 Power Quality Protection8.19.2 Power System Fault Protection8.19.3 System Protection for Faults on Distributed Generator Facilities8.19.4 Other Intertie Protection Considerations8.19.5 Induction Generators/Static Inverters/Wind Farms8.19.5.1 Induction Generators8.19.5.2 Inverters8.19.5.3 Wind Farms8.19.6 Practical Considerations of Distributed Generation8.20 Protection SummaryBibliography
Chapter 9 - Transformer, Reactor, and Shunt Capacitor Protection
9.1 Transformers9.2 Factors Affecting Differential Protection9.3 False Differential Current9.3.1 Magnetization Inrush9.3.2 Overexcitation9.3.3 Current Transformer Saturation9.4 Transformer Differential Relay Characteristics9.5 Application and Connection of Transformer Differential Relays9.6 Example: Differential Protection Connections for a Two-Winding Wye–Delta Transformer Bank9.6.1 First Step: Phasing9.6.2 Second Step: CT Ratio and Tap Selections9.7 Load Tap-Changing Transformers9.8 Example: Differential Protection Connections for Multiwinding Transformer Bank9.9 Application of Auxiliaries for Current Balancing9.10 Paralleling CTs in Differential Circuits9.11 Special Connections for Transformer Differential Relays9.12 Differential Protection for Three-Phase Banks of Single-Phase Transformer Units9.13 Ground (Zero-Sequence) Differential Protection for Transformers9.14 Equipment for Transfer Trip Systems9.14.1 Fault Switch9.14.2 Communication Channel9.14.3 Limited Fault-Interruption Device9.15 Mechanical Fault Detection for Transformers9.15.1 Gas Detection9.15.2 Sudden Pressure9.16 Grounding Transformer Protection9.17 Ground Differential Protection with Directional Relays9.18 Protection of Regulating Transformers9.19 Transformer Overcurrent Protection9.20 Transformer Overload-Through-Fault-Withstand Standards9.21 Examples: Transformer Overcurrent Protection9.21.1 Industrial Plant or Similar Facility Served by a 2500 kVA, 12 kV: 480 V Transformer with 5.75% Impedance9.21.2 Distribution or Similar Facility Served by a 7500 kVA, 115: 12 kV Transformer with 7.8% Impedance9.21.3 Substation Served by a 12/16/20 MVA, 115: 12.5 kV Transformer with 10% Impedance9.22 Transformer Thermal Protection9.23 Overvoltage on Transformers9.24 Summary: Typical Protection for Transformers9.24.1 Individual Transformer Units9.24.2 Parallel Transformer Units9.24.3 Redundancy Requirements for Bulk Power Transformers9.25 Reactors9.25.1 Types of Reactors9.25.2 General Application of Shunt Reactors9.25.3 Reactor Protection9.26 Capacitors9.27 Power System Reactive Requirements9.28 Shunt Capacitor Applications9.29 Capacitor Bank Designs9.30 Distribution Capacitors Bank Protection9.31 Designs and Limitations of Large Capacitor Banks9.32 Protection of Large Capacitor Banks9.33 Series Capacitor Bank Protection9.34 Capacitor Bank Protection Application IssuesBibliographyAppendix 9.1 Application of Digital Transformer Differential RelaysA.9.1-1 Current Magnitude CompensationA.9.1-2 Phase Angle CompensationA.9.1-3 Other Features of Digital Transformer Differential Relays
Chapter 10 - Bus Protection
10.1 Introduction: Typical Bus Arrangements10.2 Single Breaker–Single Bus10.3 Single Buses Connected with Bus Ties10.4 Main and Transfer Buses with Single Breakers10.5 Single Breaker–Double Bus10.6 Double Breaker–Double Bus10.7 Ring Bus10.8 Breaker-and-Half Bus10.9 Transformer–Bus Combination10.10 General Summary of Buses10.11 Differential Protection for Buses10.11.1 Multirestraint Current Differential10.11.2 High-Impedance Voltage Differential10.11.3 Air-Core Transformer Differential10.11.4 Moderate High-Impedance Differential10.12 Other Bus Differential Systems10.12.1 Time–Overcurrent Differential10.12.2 Directional Comparison Differential10.12.3 Partial Differential10.12.4 Short Time-Delay Scheme: Instantaneous Blocking10.13 Ground-Fault Bus10.14 Protection Summary10.15 Bus Protection: Practical ConsiderationsBibliography
Chapter 11 - Motor Protection
11.1 Introduction11.2 Potential Motor Hazards11.3 Motor Characteristics Involved in Protection11.4 Induction Motor Equivalent Circuit11.5 General Motor Protection11.6 Phase-Fault Protection11.7 Differential Protection11.8 Ground-Fault Protection11.9 Thermal and Locked-Rotor Protection11.10 Locked-Rotor Protection for Large Motors (21)11.11 System Unbalance and Motors11.12 Unbalance and Phase Rotation Protection11.13 Undervoltage Protection11.14 Bus Transfer and Reclosing11.15 Repetitive Starts and Jogging Protection11.16 Multifunction Microprocessor Motor Protection Units11.17 Synchronous Motor Protection11.18 Summary: Typical Protection for Motors11.19 Practical Considerations of Motor ProtectionBibliography
Chapter 12 - Line Protection
12.1 Classifications of Lines and Feeders12.2 Line Classifications for Protection12.2.1 Distribution Lines12.2.2 Transmission and Subtransmission Lines12.3 Techniques and Equipment for Line Protection12.3.1 Fuses12.3.2 Automatic Circuit Reclosers12.3.3 Sectionalizers12.3.4 Coordinating Time Interval12.4 Coordination Fundamentals and General Setting Criteria12.4.1 Phase Time–Overcurrent Relay Setting12.4.2 Ground Time–Overcurrent Relay Setting12.4.3 Phase and Ground Instantaneous Overcurrent Relay Setting12.5 Distribution Feeder, Radial Line Protection, and Coordination12.6 Example: Coordination for a Typical Distribution Feeder12.6.1 Practical Distribution Coordination Considerations12.7 Distributed Generators and Other Sources Connected to Distribution Lines12.8 Example: Coordination for a Loop System12.9 Instantaneous Trip Application for a Loop System12.10 Short-Line Applications12.11 Network and Spot Network Systems12.12 Distance Protection for Phase Faults12.13 Distance Relay Applications for Tapped and Multiterminal Lines12.14 Voltage Sources for Distance Relays12.15 Distance Relay Applications in Systems Protected by Inverse-Time–Overcurrent Relays12.16 Ground-Fault Protection for Lines12.17 Distance Protection for Ground Faults and Direction Overcurrent Comparisons12.18 Fault Resistance and Relaying12.19 Directional Sensing for Ground–Overcurrent Relays12.20 Polarizing Problems with Autotransformers12.21 Voltage Polarization Limitations12.22 Dual Polarization for Ground Relaying12.23 Ground Directional Sensing with Negative Sequence12.24 Mutual Coupling and Ground Relaying12.25 Ground Distance Relaying with Mutual Induction12.26 Long EHV Series-Compensated Line Protection12.27 Backup: Remote, Local, and Breaker Failure12.28 Summary: Typical Protection for Lines12.29 Practical Considerations of Line ProtectionBibliography
Chapter 13 - Pilot Protection
13.1 Introduction13.2 Pilot System Classifications13.3 Protection Channel Classifications13.4 Directional Comparison Blocking Pilot Systems13.5 Directional Comparison Unblocking Pilot System13.5.1 Normal-Operating Condition (No Faults)13.5.2 Channel Failure13.5.3 External Fault on Bus G or in the System to the Left13.5.4 Internal Faults in the Protected Zone13.6 Directional Comparison Overreaching Transfer Trip Pilot Systems13.6.1 External Fault on Bus G or in the System to the Left13.6.2 Internal Faults in the Protected Zone13.7 Directional Comparison Underreaching Transfer Trip Pilot Systems13.7.1 Zone Acceleration13.8 Phase Comparison: Pilot Wire Relaying (Wire Line Channels)13.9 Phase Comparison: Audio Tone or Fiber-Optic Channels13.9.1 External Fault on Bus H or in the System to the Right13.9.2 Internal Faults in the Protected Zone13.10 Segregated Phase Comparison Pilot Systems13.11 Single-Pole–Selective-Pole Pilot Systems13.12 Directional Wave Comparison Systems13.13 Digital Current Differential13.14 Pilot Scheme Enhancements13.14.1 Transient Blocking13.14.2 Weak Infeed Logic13.14.3 Breaker Open Keying13.15 Transfer Trip Systems13.16 Communication Channels for Protection13.16.1 Power-Line Carrier: On–Off or Frequency Shift13.16.2 Pilot Wires: Audio Tone Transmission13.16.3 Pilot Wires: 50 or 60 Hz Transmission13.16.4 Digital Channels13.17 Digital Line Current Differential Systems13.17.1 Characteristics of Line Differential Schemes13.17.2 Line Differential Issues13.17.2.1 Current Sample Alignment13.17.2.2 Current Transformer Saturation13.17.2.3 Line Charging Current13.17.2.4 Sensitivity13.17.3 Line Differential Design Enhancements13.17.3.1 Sensitivity Enhancement13.17.3.2 Maintaining Adequate Data Alignment13.17.3.3 Mitigating Impacts of Current Transformer Saturation13.17.3.4 Accounting for Line Charging Current13.17.3.5 Current-Ratio Differential Concept13.17.4 Line Differential Application13.18 Pilot Relaying: Operating Experiences13.19 SummaryBibliographyAppendix 13.1 Protection of Wire Line Pilot Circuits
Chapter 14 - Stability, Reclosing, Load Shedding, and Trip Circuit Design
14.1 Introduction14.2 Electric Power and Power Transmission14.3 Steady-State Operation and Stability14.4 Transient Operation and Stability14.5 System Swings and Protection14.6 Out-of-Step Detection by Distance Relays14.7 Automatic Line Reclosing14.8 Distribution Feeder Reclosing14.9 Subtransmission and Transmission-Line Reclosing14.10 Reclosing on Lines with Transformers or Reactors14.11 Automatic Synchronizing14.12 Frequency Relaying for Load Shedding–Load Saving14.13 Underfrequency Load-Shedding Design14.13.1 Underfrequency Load-Shedding Criteria14.13.2 Underfrequency Load-Shedding Scheme Architecture14.13.3 Underfrequency Control Scheme Design14.14 Performance of Underfrequency Load-Shedding Schemes14.15 Frequency Relaying for Industrial Systems14.16 Voltage Collapse14.17 Voltage Collapse Mitigating Techniques14.18 Protection and Control Trip Circuits14.19 Substation DC Systems14.20 Trip Circuit Devices14.20.1 Auxiliary Relays14.20.2 Targeting and Seal-In Devices14.20.3 Switches and Diodes14.20.4 Trip Coils14.21 Trip Circuit Design14.22 Trip Circuit Monitoring and Alarms14.23 Special Protection Schemes14.24 Practical Considerations: Special Protection SchemesBibliography
Chapter 15 - Microprocessor Applications and Substation Automation
15.1 Introduction15.2 Microprocessor-Based Relay Designs15.3 Programmable Logic Controllers15.4 Application of Microprocessor Relays15.5 Programming of Microprocessor Relaying15.5.1 Boolean Algebra15.5.2 Control Equation Elements15.5.3 Binary Elements15.5.4 Analog Quantities15.5.5 Math Operators15.5.6 Settings15.6 Attributes of Microprocessor-Based Relays15.7 Protection Enhancements15.7.1 Distribution Protection Systems15.7.2 Transmission Protection Systems15.8 Multifunctional Capability15.9 Wiring Simplification15.10 Event Reports15.10.1 Types of Event Reports15.11 Commissioning and Periodic Testing15.12 Setting Specifications and Documentation15.13 Fault Location15.14 Power System Automation15.15 Practical Observations: Microprocessor Relay ApplicationBibliography
Chapter 16 - Improving Protective System Performance
16.1 Performance Measurement Techniques16.2 Measuring Protective System Performance16.3 Analyzing Protective System Misoperations16.3.1 Parameters for Measuring Protective System Performance16.3.2 Regulatory Issues16.4 NERC Standard PRC-00416.5 Procedures for Implementing PRC-00416.6 Tools for Analyzing Power System Events16.6.1 Fault Recorders16.6.2 Dynamic Disturbance Recorders16.6.3 Sequence-of-Events Recorders16.7 Overview of Major Power Outages16.7.1 Northeast Blackout (November 9, 1965)16.7.2 West Coast Blackout (July 2, 1996)16.7.3 Northeast United States/Canadian Blackout (August 14, 2003)16.7.4 Florida Blackout (February 26, 2008)16.7.5 Pacific Southwest Outage (September 8, 2011)16.7.6 Summary16.8 Relay Setting Loadability16.8.1 Three-Terminal Lines16.8.2 Remote Backup Protection16.9 NERC Standard PRC-02316.9.1 Loadability of Distance Relays16.9.2 Requirements for Transformer Overload Settings16.9.3 Loadability of Pilot Schemes16.9.3.1 Loadability of DCB Pilot Schemes16.9.3.2 Loadability of POTT Pilot Schemes16.9.4 Switch-On-to-Fault Loadability16.10 Loadability Limits on Non-BES Lines16.11 Generator Trips during Disturbances16.12 Protection System Maintenance16.13 Grid Automation: Protection Aspects16.14 SummaryBibliography
Chapter 17 - Problems
Chapter 2Chapter 3Chapter 4Chapter 5Chapter 7Chapter 8Chapter 9Chapter 10Chapter 11Chapter 12Chapter 13Chapter 14Chapter 16

Content preview from Protective Relaying, 4th Edition

Chapter 6

Protection Fundamentals and Basic Design Principles

6.1 Introduction

The best protection technique now and for more than 50 years is that known as differential protection. Here the electrical quantities entering and leaving the protected zone or area are compared by current transformers (CTs). If the net between all the various circuits is zero, it is assumed that no fault or intolerable problem exists. However, if the net is not zero, an internal problem exists and the difference current can operate the associated relays. In general, internal faults provide significant operating current, even for fairly light faults.

Differential protection is universally applicable to all parts of the power system: generators, motors, buses, transformers, ...

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Protective Relaying, 4th Edition

by J. Lewis Blackburn, Thomas J. Domin

Protection Fundamentals and Basic Design Principles

6.1 Introduction

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