Protective Relay Principles: 1st Edition (Hardback) book cover

Protective Relay Principles

1st Edition

By Anthony M. Sleva

CRC Press

368 pages | 195 B/W Illus.

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Hardback: 9780824753726
pub: 2009-02-23
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Description

Improve Failure Detection and Optimize Protection

In the ever-evolving field of protective relay technology, an engineer’s personal preference and professional judgment are as important to power system protection as the physical relays used to detect and isolate abnormal conditions.

Invaluable Insights from an Experienced Expert

Protective Relay Principles focuses on probable power system failure modes and the important characteristics of the protective relays used to detect these postulated failures. The book presents useful new concepts in a way that is easier to understand because they are equally relevant to older, electromechanical and solid-state relays, and newer, more versatile microprocessor-based relays. It introduces the applications, considerations, and setting philosophies used in transmission-line, distribution-line, and substation applications, covering concepts associated with general system operations and fault detection. Topics include relay load limits, cold load pickup, voltage recovery, and arc flash. The author also delves into the philosophies that engineers employ in both urban and rural areas, with a detailed consideration of setpoint function.

Analysis of Key Concepts That Are Usually Just Glossed Over

This versatile text is ideal for new engineers to use as a tutorial before they open the instruction manuals that accompany multi-function microprocessor-based relays. Guiding readers through the transient loading conditions that can result in relay misoperation, the author elaborates on concepts that are not generally discussed, but can be very helpful in specific applications. Readers will come away with an excellent grasp of important design considerations for working with overcurrent, over- and undervoltage, impedance, distance, and differential type relay functions, either individually or in combination. Also useful for students as a textbook, this book includes practical examples for many applications, and offers guidance for more unusual ones.

Table of Contents

Power System Components

Transmission Lines

Distribution Lines

Transformers

Circuit Breakers

Buses

Switchyards

Fuses

Substations

Reclosers

Generators

Power System Subcomponents

Current Transformers

Voltage Transformers

Capacitive Coupled Voltage Transformers

Protective Relays

Control Relays

Master Trip Relays

Programmable Logic Controllers

Insulators

Bushings

Cable Terminators

Disconnect Switches

Air Break Switches

Motor-Operated Air Break Switches

Ground Switches

Surge Arrestors

Sectionalizers

Batteries

Abnormal Power System Conditions

Short Circuits

Overloads

Overvoltage

Undervoltage

Overfrequency

Underfrequency

Open Phase

Single Phasing

Phase Unbalance

Volts per Hertz

Short-Circuit Calculations

Symmetrical Components

Positive Sequence Networks

Negative Sequence Networks

Zero Sequence Networks

Operators

Sequence Diagram Connections—Three-Phase Faults

Sequence Diagram Connections—Phase-to-Phase Faults

Sequence Diagram Connections—Single Phase-to-Ground Faults

Per-Unit Quantities

Sample Calculations

Sample Calculations—Three-Phase Faults

Sample Calculations—Phase-to-Phase Faults

Sample Calculations—Single Phase-to-Ground Faults

Sample Calculations—Mutual Coupling

Protective Relay Functions

Time Overcurrent Relay (51)

Instantaneous Overcurrent Relay (50)

Overvoltage Relay (59)

Undervoltage Relay (27)

Distance Relay (21)

Differential Relay (87)

Directional Relay (67)

Underfrequency Relay (81)

Overfrequency Relay (81)

Protective Relay Functional Combinations

Voltage-Controlled Time Overcurrent Relay

Torque-Controlled Time Overcurrent Relay

Logic-Controlled Instantaneous Overcurrent Relay

Torque-Controlled Instantaneous Overcurrent Relay

Logic-Controlled Overvoltage Relay

Logic-Controlled Undervoltage Relay

Logic-Controlled Distance Relay

Current-Supervised Distance Relay

Logic-Supervised Differential Relay

Current-Supervised Differential Relay

Current-Supervised Underfrequency Relay

Dual Underfrequency Relays

Zones and Regions of Protection

Zones of Protection

Regions of Protection

Physical Characteristics of Protective Relays

Electromechanical Relays

Solid-State Relays

Microprocessor-Based Relays

Relay Operation

Relay Packaging

Setting Considerations

Power System Configuration and Operation

Power System Requirements

Maximum Short-Circuit Current—Fault in Protected Zone

Maximum Relay Short-Circuit Current—Fault in Adjacent Zone

Minimum Relay Short-Circuit Current—Fault in Protected Zone

Fault Current Ratio

Relay Sensitivity

Circuit Loading

Relay Coordination

Directionality

Accuracy of Calculations

Device Accuracy

Circuit-Breaker Operating Times

Transient Overreach

Cold Load Inrush

Redundancy

Relay Drift

Security

Arc Flash Hazard

Circuit Breaker-Failure Detection and Isolation

Free-Standing CT Flashover Detection

Switchable Settings

Recovery Voltage Inrush

Protection and Control Schemes

Alternative Protective Relay Trip Logic

Supervised Protective Relay Logic

Protective Relay Coordination

Instantaneous Current Relays

Time Overcurrent Relays

Instantaneous Voltage Relays

Time-Delayed Voltage Relays

Instantaneous (Zone 1) Impedance Relays

Time-Delayed (Zone 2 or Zone 3) Impedance Relays

Instantaneous Frequency Relays

Time-Delayed Frequency Relays

Distribution-Line Protection: Radial Lines

Distribution-Line Protection Philosophy

Setpoint Margin Considerations

Distribution-Line Protection

Time Overcurrent Phase Relay Pickup Setting—Load Capability

Time Overcurrent Ground Relay Pickup Setting—Load Capability

Low Set Instantaneous Overcurrent Phase Relay Pickup Setting

Low-Set Instantaneous Overcurrent Ground Relay Pickup Setting

High-Set Instantaneous Overcurrent Phase Relay Pickup Setting

High-Set Instantaneous Overcurrent Ground Relay Pickup Setting

Time Overcurrent Phase Relay Pickup Setting—Sensitivity Check

Time Overcurrent Phase Relay Pickup Setting—Time Delay

Time Overcurrent Phase Relay Pickup Setting—Upstream Coordination

Time Overcurrent Ground Relay Pickup Setting—Sensitivity Check

Time Overcurrent Ground Relay Pickup Setting—Time Delay

Time Overcurrent Relay Ground Pickup Setting—Upstream Coordination

Distribution-Line Protection: Network Lines

Networked Distribution-Line Protection Philosophy

Setpoint Margin Considerations

Distribution-Line Protection

Time Overcurrent Phase Relay Pickup Setting—Load Capability

Time Overcurrent Ground Relay Pickup Setting—Load Capability

Instantaneous Overcurrent Phase Relay Pickup Setting

Instantaneous Overcurrent Ground Relay Pickup Setting

Definite Time Overcurrent Phase Relay Pickup Setting

Definite Time Overcurrent Ground Relay Pickup Setting

Time Overcurrent Phase Relay Pickup Setting—Sensitivity Check

Time Overcurrent Phase Relay Pickup Setting—TimeDelay

Time Overcurrent Phase Relay Pickup Setting—Upstream Coordination

Time Overcurrent Ground Relay Pickup Setting—Sensitivity Check

Time Overcurrent Ground Relay Pickup Setting—Time Delay

Time Overcurrent Relay Ground Pickup Setting—Upstream Coordination

Transmission-Line Protection

Phase Distance Relays

Ground Distance Relays

Overcurrent Ground Relays

Instantaneous Overcurrent Ground Relays

Time Overcurrent Ground Relays

Directional Unit Sensitivity for Ground Faults

Current-Polarized Ground Relays

Voltage-Polarized Ground Relays

High-Speed Relaying Schemes

Line Differential Scheme

CT Saturation

Transformer Protection

Transformer External Fault Protection

Bus Protection

Overcurrent Bus Differential

Bus Differential—Quick Trip Settings

Bus Differential—Time Overcurrent Settings

High-Impedance Bus Differential

Sensitivity for Bus Faults

Breaker Failure Relaying

Remote Breaker Failure Protection—Phase Distance Relays

Remote Breaker Failure Protection—Overcurrent Ground Relays

Remote Breaker Failure Protection—Watt-Type Ground

Relays

Local Breaker Failure Protection—Traditional

Control Elementary Diagram

Control Elementary Diagram

Local Breaker Failure Protection for Transformer Protection

Capacitor Protection

Neutral Current Monitoring

Midpoint Voltage Monitoring

Shunt and Series Reactor Protection

Grid Protection

Voltage Issues

Undervoltage Protection—Grid Protection

Undervoltage Protection—Load Protection

Overvoltage Protection—Grid Protection

Overvoltage Protection—Load Protection

Frequency Control

Underfrequency Relaying

Overfrequency Relaying

Index

About the Author

Anthony Sleva is president of Sleva Associates, an electrical consulting and training company. He is a registered Professional Engineer with a BSEE degree from Pennsylvania State University. During his career, he has designed electrical systems for nuclear generating stations; designed 500-230 KV, 230-69 KV, 138-12 KV and 69-12 KV substations; provided technical support to power dispatchers, system operators and plant operators; and developed technical training programs for technicians, drafters, designers and technical clerks. Mr. Sleva specializes in the analysis of power system events that cause the loss of customer load and/or the initiation of emergency load control procedures as well as events that may have been caused by incorrect protective relay actuations.

Subject Categories

BISAC Subject Codes/Headings:
TEC007000
TECHNOLOGY & ENGINEERING / Electrical