Power System Protection: Fundamentals and Applications

Cover
Title Page
Copyright
Contents
About the Authors
Preface
Acknowledgements
Chapter 1 What Is Power System Protection, Why Is It Required and Some Basics?
	1.1 What Is Power System Protection?
	1.2 Why Is Power System Protections Required?
		1.2.1 Minimize Primary Equipment Damage
		1.2.2 Provide Continuity of Service by Minimizing Outage Time and Service
		1.2.3 Promote Safety
		1.2.4 Maintaining Power System Integrity
	1.3 Some Basic Protection System Terms and Information
		1.3.1 Relay
		1.3.2 Protective Relays
		1.3.3 Protective Relaying
		1.3.4 Protection Engineering
		1.3.5 Protection System Objectives
		1.3.6 Protection System Characteristics
			1.3.6.1 Selectivity
			1.3.6.2 Sensitivity
			1.3.6.3 Speed
		1.3.7 Protection System Reliability
			1.3.7.1 Dependability
			1.3.7.2 Security
		1.3.8 Protection System Backup
			1.3.8.1 Remote Backup
			1.3.8.2 Local Backup
		1.3.9 Protection System Redundancy
	References
Chapter 2 Basic Power System Protection Components
	2.1 General Description
	2.2 Power System Protection Components
		2.2.1 Instrument Transformers
		2.2.2 Protective Relays
		2.2.3 Auxiliary Logic
			2.2.3.1 Auxiliary Relays
			2.2.3.2 Application of Auxiliary Relays
		2.2.4 Panels and Racks
		2.2.5 Battery Systems Used for Protections
		2.2.6 Telecommunications
	2.3 Physical Implementation
		2.3.1 Relay and Control Building
		2.3.2 Location of Instrument Transformers
		2.3.3 Terminations
		2.3.4 Protection Isolation Devices
		2.3.5 Wiring and Cable (Control Wiring)
	2.4 Power System Isolation Devices and Control Interfaces
		2.4.1 Isolation Devices
		2.4.2 Control Interfaces
	2.5 Redundancy Arrangements
		2.5.1 Instrument Transformers
		2.5.2 Dual Breaker Trip Coils
Chapter 3 AC Signal Sources
	3.1 Introduction
	3.2 Current Transformers
		3.2.1 Current Transformer Secondary Burden
		3.2.2 Current Transformer Types
			3.2.2.1 Bar‐Type CT
			3.2.2.2 Bushing‐Type CT
			3.2.2.3 Window‐Type CT
			3.2.2.4 Wound‐Type CT
		3.2.3 Current Transformer Polarity
		3.2.4 Current Transformer Ratios
		3.2.5 Auxiliary Transformers
		3.2.6 Current Transformer Accuracy Classifications
		3.2.7 General Characteristics of CTs
		3.2.8 Response of CTs Under Transient Power System Conditions
			3.2.8.1 The Effect of CT Saturation on Protections
			3.2.8.2 Causes of CT Saturation
			3.2.8.3 Flux Remanence in the CT Core
			3.2.8.4 Use of Air Gaps to Reduce Remanence
			3.2.8.5 Methods to Ensure Correct CT Performance
		3.2.9 General Requirements for CT Sizing
			3.2.9.1 Maximum Expected Load Current
			3.2.9.2 Maximum Symmetrical Fault Current
			3.2.9.3 Maximum CT Burden
			3.2.9.4 Calculate the Steady‐state CT Secondary Voltage (VS)
			3.2.9.5 CT Application Example
	3.3 Voltage Sources
		3.3.1 Magnetic Voltage Transformers
			3.3.1.1 Magnetic Voltage Transformers Equivalent Circuit
			3.3.1.2 Protection of VTs
		3.3.2 Capacitive Voltage Transformer (CVT)
		3.3.3 Bushing Potential Devices
	References
Chapter 4 Basic Types of Protection Relays and Their Operation
	4.1 General
	4.2 Fundamental Principles and Characteristics
		4.2.1 Non‐directional Induction Disk Overcurrent
		4.2.2 Induction Principle of Operation
	4.3 Overcurrent
		4.3.1 Induction Disc Time‐Overcurrent
		4.3.2 Inverse Time‐Overcurrent Relay
			4.3.2.1 Inverse Time‐Overcurrent Characteristics
			4.3.2.2 Basic Pickup Current Setting
			4.3.2.3 Time Dial Adjustment
			4.3.2.4 Setting Adjustments for an Inverse Time‐Overcurrent Relay
		4.3.3 Time Coordination with Overcurrent Relays
			4.3.3.1 Coordination Time for Electromechanical Relays
			4.3.3.2 Coordination Time for Digital Relays
		4.3.4 Directional Overcurrent Relays
			4.3.4.1 Method of Directioning
			4.3.4.2 The Watt‐Hour Structure
			4.3.4.3 The Induction Cup Structure
			4.3.4.4 Relay Phase Relationship of Voltage and Current in a Directional Relay
			4.3.4.5 Typical Application of Directional Phase Overcurrent Relays
			4.3.4.6 Typical Application of Ground Directional Overcurrent Relays
	4.4 Differential
		4.4.1 General
		4.4.2 Differential Principle Used in Bus Protection
			4.4.2.1 Fundamental Principle of Operation
			4.4.2.2 Security for Out‐of‐Zone Faults
			4.4.2.3 Low Impedance Differential Protection
			4.4.2.4 High Impedance Differential Protection
		4.4.3 Differential Principle Used in Transformer Protection
			4.4.3.1 Percent Differential Relay
	4.5 Distance
		4.5.1 General
		4.5.2 Need for Distance Protection
		4.5.3 Impedance Relay Principle of Operation
		4.5.4 MHO Relay Principle of Operation
			4.5.4.1 Offset‐MHO Relay Principle of Operation
			4.5.4.2 Reactance – Type Distance Relay
			4.5.4.3 Blinder‐Type Distance Relay
	Reference
Chapter 5 Protection Information Representation, Nomenclature, and Jargon
	5.1 General
	5.2 Protection Drawing Types
		5.2.1 Single‐line Diagram
		5.2.2 Three‐Phase Diagram (AC EWD)
			5.2.2.1 Transcription of Information from AC EWD to Single‐Line Diagrams
		5.2.3 DC Elementary Wiring Diagrams – Also Known as DC Control Diagrams
		5.2.4 Electrical Arrangement (EA)
		5.2.5 Connection Wiring Diagrams (CWD)
		5.2.6 Protection Logic Diagrams
		5.2.7 Protection Settings Records and Support Information
		5.2.8 Protection Relay Threshold/Pickup Settings
		5.2.9 Relay Configuration and Settings File
	5.3 Nomenclature and Device Numbers
		5.3.1 Commonly Used Protection Device Numbers
		5.3.2 Prefix and Suffix Meaning
		5.3.3 Interlocks
	5.4 Classification of Relays
		5.4.1 Methods of Operation
		5.4.2 Response Characteristics
	5.5 Protection Jargon
		5.5.1 Relay Operation and Performance
		5.5.2 Protection System Operation and Performance
	Reference
Chapter 6 Per‐Unit System and Fault Calculations
	6.1 General
	6.2 Per‐Unit
		6.2.1 Base Quantity Equations
			6.2.1.1 Establish the Base Voltage (kV) and Power (MVA)
			6.2.1.2 From Base Voltage and Power, Calculate the Base Current and Impedance
		6.2.2 Per‐Unit General
		6.2.3 Per‐Unit Impedance
		6.2.4 Conversion of PU Values To Different Bases
		6.2.5 A Summary for Solving a Problem Using Per Unit
		6.2.6 Example
	6.3 Fundamental Need for Fault Information
		6.3.1 Types of Faults
			6.3.1.1 Balanced vs. Unbalanced
	6.4 Symmetrical Components
		6.4.1 Theory of Symmetrical Components
			6.4.1.1 Positive Sequence Phasors
			6.4.1.2 Negative Sequence Phasors
			6.4.1.3 Zero‐Sequence Phasors
		6.4.2 Phase Quantities In Terms of Sequence Components
	6.5 Sequence Impedances of Power Apparatus
		6.5.1 Synchronous Machinery
		6.5.2 Transmission Lines
		6.5.3 Transformers
			6.5.3.1 Equivalent Circuit: Positive and Negative Sequence Impedances
			6.5.3.2 Zero‐Sequence Circuit and Impedance
			6.5.3.3 Zero‐sequence Impedance with Neutral Grounding Impedance
			6.5.3.4 Banks of Three, Single‐Phase Transformers
			6.5.3.5 Typically Used Transformers and Models
	6.6 Balanced Fault Analysis
		6.6.1 Balanced Fault Calculations
		6.6.2 Simplifying Assumptions
	6.7 Sequence Networks
		6.7.1 Sequence Network Interconnections
			6.7.1.1 Principle of Interconnections
	6.8 Summary of Unbalance Fault Calculations
		6.8.1 Positive Sequence Diagram
		6.8.2 Negative Sequence Diagram:
		6.8.3 Zero‐Sequence Diagram
		6.8.4 Conduct the Fault Study
	6.9 High‐Level Summary of the Fault Calculation Process
		6.9.1 Develop a Single‐Line Diagram of the Studied Area
		6.9.2 Determine the Studied Power System Element Impedances
		6.9.3 Develop Sequence Impedance Models
		6.9.4 Determine the Fault Types and System Conditions
		6.9.5 Conduct the Fault Studies and Determine Relay Quantities
	6.10 Useful Fault Calculation Formulas/Methods
		6.10.1 Conversion from Short Circuit Values to System Impedances
	6.11 Fault Calculation Examples
		6.11.1 Three‐Phase Fault Example
		6.11.2 Line‐to‐Ground Fault Example
			6.11.2.1 Positive Sequence
			6.11.2.2 Negative Sequence Network
			6.11.2.3 Zero‐Sequence Network
			6.11.2.4 Reduction in the Positive Sequence Network
			6.11.2.5 Reduction in the Zero‐Sequence Network
			6.11.2.6 Calculate the L‐G Fault
	References
Chapter 7 Protection Zones
	7.1 Protection Zones General
	7.2 Zones Defined
	7.3 Zone Overlap Around Breakers
	7.4 Protection Zoning at Stations
		7.4.1 HV Switching Stations
		7.4.2 LV Distribution Stations
			7.4.2.1 The Transformer Zone
			7.4.2.2 The Bus Zone
			7.4.2.3 The Distribution Feeder Zone
	7.5 Protection Zones in General
		7.5.1 Lines
		7.5.2 Transformers
		7.5.3 Generators
		7.5.4 Protection Zones Overlapping Between Stations
	7.6 Backup Protection
		7.6.1 Remote Backup
		7.6.2 Local Backup
	7.7 CT Configuration and Protection Trip Zones
		7.7.1 CTs Connected in Wye
		7.7.2 CTs Connected in Delta
	7.8 Where Protections Zones do not Overlap Around Breakers
		7.8.1 Blind Spot Created by Non‐Overlap of Protections Zones around Breakers
	7.9 Lines Terminating Directly on Buses at a HV Switching Station
Chapter 8 Transformer Protection
	8.1 Introduction
	8.2 General Principles
	8.3 Differential Protection Power Transformers
		8.3.1 Factors Affecting Transformer Differential Protection
		8.3.2 Phase Shifting from Primary to Secondary
		8.3.3 The Flow of Zero‐Sequence Current
			8.3.3.1 Substation Grounding Requirements
			8.3.3.2 Artificial Ground Sources
		8.3.4 Flow of Zero‐Sequence Currents in Differential Circuits
			8.3.4.1 Delta–Wye Transformer
			8.3.4.2 Wye–Delta Transformer
		8.3.5 Restricted Ground Fault Protection
			8.3.5.1 Theory of Operation
		8.3.6 Percent Differential Relay Settings
			8.3.6.1 Current Transformer Mismatch and Under‐Load Tap Changing
			8.3.6.2 Percent Differential Relay Operation
			8.3.6.3 Maximum System Unbalance
			8.3.6.4 Introduction of Slope Under Fault Conditions
			8.3.6.5 Effect of Magnetizing Current Inrush on Differential Relays
			8.3.6.6 Third Restraint Winding
			8.3.6.7 Transformer Overload Protections for Double Transformer Contingency
	8.4 Percent Differential Protection Autotransformers
	8.5 Transformer Percent Differential Setting Examples
		8.5.1 Power Transformer Percent Differential Protection Setting Example
		8.5.2 Autotransformer Percent Differential Protection Setting Example
		8.5.3 Power Transformer Restricted Ground Fault Setting Example
	Reference
Chapter 9 Bus Protection
	9.1 Introduction
	9.2 Typical Bus Arrangements
	9.3 Bus Protection Requirements
	9.4 Methods of Protecting Buses
		9.4.1 Differential Protection
			9.4.1.1 Low Impedance Bus Differential Protection
			9.4.1.2 High Impedance Bus Differential Protection
			9.4.1.3 Differential Protection with Digital Relays
			9.4.1.4 Bus Differential Protection Zones
		9.4.2 Bus Blocking Protection
	9.5 Example High Impedance Differential Protection Setting
	Reference
Chapter 10 Breaker Failure Protection and Automatic Reclosing
	10.1 Introduction
	10.2 Breaker Failure General Background
		10.2.1 Typical Breaker Failure Tripping Zones
		10.2.2 Principles of Breaker Failure Protection
		10.2.3 Requirements for Breaker Failure Protection
		10.2.4 Types of Initiation
		10.2.5 Speed of Operation
		10.2.6 Determination of Breaker Failure Condition
			10.2.6.1 62a Logic Path (Mechanical‐Breaker Failure Detection)
			10.2.6.2 62b Logic Path (Electrical Breaker Failure Detection)
			10.2.6.3 62c Logic Path (Low Magnitude Fault Breaker Failure Detection)
		10.2.7 Additional Generic Features of Breaker Failure Protection
			10.2.7.1 Early Trip Function
			10.2.7.2 Breaker Test Switch Supervision
		10.2.8 Circuit Operation of Breaker Failure
		10.2.9 Coordination with Other Protections
		10.2.10 Non‐Duplication of Breaker Failure
			10.2.10.1 Non‐Duplication of Breaker Failure Example
			10.2.10.2 Impact on Protection Separation
		10.2.11 Load‐Substation Bus Fault and LV Breaker Failure
		10.2.12 Pedestal Breaker and Free‐Standing CT Frame Leakage Protection
			10.2.12.1 Protection Blind Spot
			10.2.12.2 Frame Leakage Protection
	10.3 Breaker Automatic Reclosing General Background
		10.3.1 Automatic Reclosing Timing
		10.3.2 Reclosing Supervision
		10.3.3 Lockout
		10.3.4 Long‐Time Cancel
		10.3.5 Initiation and Cancellation of Reclosing
Chapter 11 Station Protection
	11.1 Introduction
	11.2 Types of Stations
		11.2.1 Switching Stations
		11.2.2 Load Substations
	11.3 Station and Protection Architecture
		11.3.1 Terminal/Switching Station
			11.3.1.1 Breaker and Half Arrangement
			11.3.1.2 Ring Bus Arrangement
		11.3.2 Load‐Substation Typical Arrangement
			11.3.2.1 Load Substation with Double Transformer Differential Protection
			11.3.2.2 Load Substation with Single Transformer Differential Protection
		11.3.3 Fault Isolation via HV Isolating Devices
			11.3.3.1 Normally Open Bus‐Tie Breaker
			11.3.3.2 Normally Closed Bus‐Tie Breaker
		11.3.4 Fault Isolation via Tele‐Protection
		11.3.5 Station Tele‐protection Subsystems
			11.3.5.1 Tele‐Protection Using Frequency Shift Keying
			11.3.5.2 Tele‐Protection Using T1 (Digital)
	11.4 Station Switchgear Type
		11.4.1 Terminal/Switching Station Outdoor Switchgear
		11.4.2 Terminal Station Indoor Switchgear
		11.4.3 Load‐Substation Outdoor Switchgear
		11.4.4 Load‐Substation Indoor Switchgear
	11.5 Sub‐Transmission Types and Station Grounding
		11.5.1 Exclusive Three‐wire Sub‐transmission
		11.5.2 Exclusive Four‐wire Sub‐transmission
		11.5.3 Combined Three‐Wire and Four‐Wire Sub‐Transmission
		11.5.4 Station Grounding Bar
	11.6 Master Ground
Chapter 12 Capacitor Bank Protection
	12.1 Capacitor Banks
	12.2 Purpose for Shunt Capacitors on Power System Networks
	12.3 Capacitor Bank Construction
		12.3.1 Individual Capacitor Units
		12.3.2 Basic Series – Parallel Arrangement
		12.3.3 Capacitor Bank Configurations
		12.3.4 Shunt Capacitor Grounding
		12.3.5 Capacitor Types by Fusing
			12.3.5.1 Fused
			12.3.5.2 No Fuses
		12.3.6 Capacitor Bank Ratings
			12.3.6.1 An Example Fused Capacitor Bank Rating
			12.3.6.2 An Example Fuseless Capacitor Bank Rating
		12.3.7 Information Required Before Protection Settings Calculations
		12.3.8 General Shunt Capacitor Bank Protection Principles
	12.4 Capacitor Bank Protection
		12.4.1 Fused Capacitor Banks
			12.4.1.1 Neutral Unbalance Protection
		12.4.2 All Capacitor Banks
			12.4.2.1 Overcurrent Protection
			12.4.2.2 Overvoltage Protection
	12.5 Capacitor Bank Breakers
	12.6 Capacitor Bank Sample Settings
		12.6.1 Double‐Wye Ungrounded Configuration – Externally Fused
		12.6.2 Single‐Wye Ungrounded Configuration – Externally Fused
		12.6.3 Wye Grounded Configuration – Fuseless
		12.6.4 Phase and Ground Overcurrent Protection
		12.6.5 Overvoltage Protection
	Reference
Chapter 13 Synchronous Generator Protection
	13.1 Introduction
	13.2 General
		13.2.1 Generator Basics and Functions
			13.2.1.1 Prime Mover
			13.2.1.2 Rotor
			13.2.1.3 Stator
			13.2.1.4 Governor Controls
			13.2.1.5 Voltage Control (Exciter and AVR)
			13.2.1.6 Station Service/UAT (Unit Auxiliary Transformer)
	13.3 Generator/Unit Transformer Protections
		13.3.1 Generator Differential (87G)
		13.3.2 Main Unit Transformer Differential (87T)
		13.3.3 Generator‐Transformer Overall Zone Protection (87O)
		13.3.4 Split‐Phase Differential (87SP Hydraulic Only)
		13.3.5 Stator Ground (59G)
		13.3.6 Loss of Excitation (40)
		13.3.7 Phase Unbalance (46)
		13.3.8 Under‐Frequency (81)
		13.3.9 Over‐excitation 24
		13.3.10 Out‐of‐Step (21–78)
		13.3.11 Reverse Power (32)
		13.3.12 Transmission System Backup
			13.3.12.1 Phase Backup (21,51V)
			13.3.12.2 Ground Backup (51TG)
	13.4 Current Transformers
	13.5 Generator Protection Sample Settings
		13.5.1 Sample Setting 1 – Large Hydraulic Generators
			13.5.1.1 Differential (87)
			13.5.1.2 Split‐Phase Differential (87SP)
			13.5.1.3 Stator Ground (59G)
			13.5.1.4 Loss of Excitation (40)
			13.5.1.5 Phase Unbalance (46)
		13.5.2 Sample Setting 2 – Large Thermal Generators
			13.5.2.1 Differential (87)
			13.5.2.2 Stator Ground (59G)
			13.5.2.3 Loss of Excitation (40)
			13.5.2.4 Over‐Excitation (24)
			13.5.2.5 Out‐of‐Step (21–78)
			13.5.2.6 Phase Unbalance (46)
	13.6 Generator Control and Protection Systems Coordination
		13.6.1 Synchronous Generator Phasor Diagrams/Capability
			13.6.1.1 Capability Curve
		13.6.2 Steady‐State Stability Limit (SSSL)
			13.6.2.1 On a RX Plot
		13.6.3 Over‐excitation V/Hz Protection and Control System Coordination
		13.6.4 Loss of Excitation Protection and Control System Coordination
	13.7 General Generator Tripping Requirements
	13.8 Breaker Failure Initiation
	Reference
Chapter 14 Transmission Line Protection
	14.1 General
	14.2 Basic Line Protection Requirements
	14.3 Impedance Relays and Why Not Just Overcurrent Relays
		14.3.1 Source Impedance
	14.4 Distance Relay Response to Fault Types
		14.4.1 Phase Fault Response
		14.4.2 Ground Fault Response
	14.5 Apparent Impedance
		14.5.1 Example of Apparent Impedance
		14.5.2 Derivation of Apparent Impedance
		14.5.3 Apparent Impedance Effect on Distance Relay Settings
		14.5.4 Maximum Apparent Impedance Calculation Example
		14.5.5 Apparent Impedance and Paralleled Conductors
		14.5.6 Load substations and Apparent Impedances
			14.5.6.1 Presence of Tapped Load substations
			14.5.6.2 Line Backup Protection at Load substations
			14.5.6.3 Large Zone 2 Reaches Seeing into the Load Substation LV Side
			14.5.6.4 Load Substations Supplied by Long Taps
	14.6 Redundancy/Backup
		14.6.1 Need for Protection Backup
		14.6.2 Remote and Local Protection Backup
			14.6.2.1 Remote Backup
			14.6.2.2 Local Backup
	14.7 Tele‐Protection (Also Known as Pilot‐Protection)
		14.7.1 Tele‐protection Architecture
		14.7.2 Protection Scheme Types for Local Backup
			14.7.2.1 Direct Underreaching Transfer Trip (DUTT)
			14.7.2.2 Permissive Overreaching Transfer Trip (POTT)
			14.7.2.3 Directional Comparison Blocking Transfer Trip (DCBTT)
	14.8 General Implications
		14.8.1 Apparent Impedance Implications
		14.8.2 Line Protection Zone 2 Reach Implications
		14.8.3 Communication Implications
	14.9 Peripheral Requirements of Distance Protection
		14.9.1 Distance Relay Response to Three‐Phase Faults
		14.9.2 Memory Action
		14.9.3 Stub‐bus and Switch Onto Fault Protection
		14.9.4 Overcurrent Supervision
			14.9.4.1 Supervising Current Elements
		14.9.5 Reclosing Coordination with Line End Open – Permissive Echo Timer
		14.9.6 Potential Sources
			14.9.6.1 Transient Response
		14.9.7 Loss of Voltage to Distance Relays
		14.9.8 Self‐Monitoring Relays
	14.10 Tele‐Protection (Pilot‐Protection) A Historical Perspective
	14.11 Tele‐Protection via Power Line Carrier
		14.11.1 Protection Architecture with PLC
			14.11.1.1 Applications
	14.12 Synchronous Optical Network (SONET)
		14.12.1 Fiber Installation
		14.12.2 Multiplexer (MUX) Equipment
		14.12.3 Definition of T1
	14.13 Three‐Terminal Lines
		14.13.1 Scheme Type and Setting Considerations
			14.13.1.1 Permissive Overreaching Scheme
			14.13.1.2 Directional Comparison Blocking Scheme
			14.13.1.3 Weak End Infeeds and Current Reversals
	14.14 Distributed Generation
		14.14.1 Traditional Protection Schemes
		14.14.2 Conventional Generation vs. Tapped Generation
			14.14.2.1 Conventional Generation
			14.14.2.2 Tapped Generation
		14.14.3 Impact on the Traditional Protection Schemes
			14.14.3.1 Permissive Overreaching Scheme
			14.14.3.2 Directional Comparison Blocking Scheme
			14.14.3.3 Line Differential Scheme
			14.14.3.4 Issues with Either Permissive or Blocking Schemes
			14.14.3.5 Preferred Scheme to Cater for Multi‐Tapped Generation
			14.14.3.6 Converting from Permissive to Blocking Schemes
			14.14.3.7 Ground Distance Protection Settings
			14.14.3.8 Load substations
	14.15 Distance Relay Response to Resistive Faults
		14.15.1 Background to Resistive Faults
			14.15.1.1 Resistive Faults
			14.15.1.2 Distance Relays and Fault Resistance Coverage
		14.15.2 Distance Relay Response to Resistive Faults
			14.15.2.1 Expanding MHO Characteristics
	14.16 Power System Considerations
		14.16.1 Loadability During Normal System Conditions
		14.16.2 Loadability During Extreme System Conditions
		14.16.3 New Loadability Criteria in North America
			14.16.3.1 Various Methods of Blinding Relays to Load
	14.17 Line Current Differential Protection
		14.17.1 Introduction
		14.17.2 Functional Description
		14.17.3 Lines with Tapped Load Substations
		14.17.4 Two‐Ended Scheme
		14.17.5 Three‐Ended Scheme
		14.17.6 Clock Synchronization
		14.17.7 Settings
			14.17.7.1 Line Current Differential Element Settings
			14.17.7.2 Distance Element Settings
			14.17.7.3 Phase and Ground Distance Settings
			14.17.7.4 Distance Elements Settings – Tapped Load‐substation Stations
			14.17.7.5 Three‐Terminal Lines
		14.17.8 System Considerations
			14.17.8.1 Weak End Infeeds and Current Reversals
			14.17.8.2 Line Loading and System Swings
			14.17.8.3 Tapped Generation
	14.18 Pilot Wire Protection
		14.18.1 Introduction
		14.18.2 Theory of Operation
	14.19 Power System Considerations
		14.19.1 Fault Clearing Time Criticality
		14.19.2 Fault Clearing Performance Categories
			14.19.2.1 Normal Clearing Times
			14.19.2.2 Breaker Failure Clearing Times
		14.19.3 Protection Planning
		14.19.4 Fault Clearing Components
	14.20 Line Setting Application Example
		14.20.1 Two‐Terminal Line Setting Example
			14.20.1.1 Setting Zone 1
			14.20.1.2 Setting Zone 2
			14.20.1.3 Peripheral Settings
		14.20.2 Long‐Tapped Transformer Line Setting Example
			14.20.2.1 Setting Zone 1
			14.20.2.2 Setting Zone 2
			14.20.2.3 Setting Zone 3
			14.20.2.4 Setting of Relay Elements
	References
Chapter 15 Subtransmission/Distribution Feeder Protection
	15.1 Subtransmission/Distribution Characteristics
	15.2 Definitions/Characteristics
		15.2.1 Distribution Network Feeder Definitions
		15.2.2 Feeder Characteristics
	15.3 Distribution Feeder Protection Devices
		15.3.1 Protection Devices
			15.3.1.1 Overcurrent Relays
			15.3.1.2 Distance Relays
			15.3.1.3 Fuses
			15.3.1.4 Automatic Reclosers (AR)
	15.4 Protection Coordination Principles
		15.4.1 Functions of Distribution/Overcurrent Protection
		15.4.2 Coordination General
			15.4.2.1 Fuse – Fuse Coordination
			15.4.2.2 Fuse – Automatic Recloser (AR)
			15.4.2.3 Primary Fuse – Transformer Damage Curve
	15.5 Feeder Energization
	15.6 Subtransmission Feeder Protection
		15.6.1 General
		15.6.2 Subtransmission Feeder Protection Requirements
		15.6.3 Subtransmission Protection
			15.6.3.1 Protection Functions
			15.6.3.2 Circuit Operation and Tripping
		15.6.4 Automatic Reclosing
			15.6.4.1 General
			15.6.4.2 Automatic Reclosing Circuit Operation
		15.6.5 Relay Settings
			15.6.5.1 Three‐Wire vs. Four Wire Feeders
			15.6.5.2 General Information/Data Requirements
			15.6.5.3 Phase Protection
			15.6.5.4 Ground Protection
	15.7 Impact of Distributed Generators (DGs) on Distribution Feeder Protection
		15.7.1 Significant Protection Issues Caused by Distributed Generation
			15.7.1.1 The Feeder Becomes Non‐Radial
			15.7.1.2 Islanding
			15.7.1.3 Internal Faults (Faults on the Feeder Connecting the DGs)
			15.7.1.4 External Faults (Faults on Feeders Adjacent to One Connected to DG)
			15.7.1.5 Automatic Reclosing and Synchronism
			15.7.1.6 Inrush Current – Interconnection Transformers
			15.7.1.7 Summary of Protection Impacts Due to DGs
	15.8 Feeder Protection Application Settings Example
	References
Index
Books in the IEEE Press Serieson Power and Energy Systems
EULA