Arc Flash Hazard Analysis and Mitigation E-Book

J. C. Das

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: IEEE Press Series on Power Engineering
• Sprache: Englisch

Seitenzahl: 818

Veröffentlichungsjahr: 2020

Beschreibung

This new edition of the definitive arc flash reference guide, fully updated to align with the IEEE's updated hazard calculations An arc flash, an electrical breakdown of the resistance of air resulting in an electric arc, can cause substantial damage, fire, injury, or loss of life. Professionals involved in the design, operation, or maintenance of electric power systems require thorough and up-to-date knowledge of arc flash safety and prevention methods. Arc Flash Hazard Analysis and Mitigation is the most comprehensive reference guide available on all aspects of arc flash hazard calculations, protective current technologies, and worker safety in electrical environments. Detailed chapters cover protective relaying, unit protection systems, arc-resistant equipment, arc flash analyses in DC systems, and many more critical topics. Now in its second edition, this industry-standard resource contains fully revised material throughout, including a new chapter on calculation procedures conforming to the latest IEEE Guide 1584. Updated methodology and equations are complemented by new practical examples and case studies. Expanded topics include risk assessment, electrode configuration, the impact of system grounding, electrical safety in workplaces, and short-circuit currents. Written by a leading authority with more than three decades' experience conducting power system analyses, this invaluable guide: * Provides the latest methodologies for flash arc hazard analysis as well practical mitigation techniques, fully aligned with the updated IEEE Guide for Performing Arc-Flash Hazard Calculations * Explores an inclusive range of current technologies and strategies for arc flash mitigation * Covers calculations of short-circuits, protective relaying, and varied electrical system configurations in industrial power systems * Addresses differential relays, arc flash sensing relays, protective relaying coordination, current transformer operation and saturation, and more * Includes review questions and references at the end of each chapter Part of the market-leading IEEE Series on Power Engineering, the second edition of Arc Flash Hazard Analysis and Mitigation remains essential reading for all electrical engineers and consulting engineers.

Leseprobe

IEEE Press445 Hoes LanePiscataway, NJ 08854

IEEE Press Editorial BoardEkram Hossain, Editor in Chief

Jón Atli Benediktsson

David Alan Grier

Elya B. Joffe

Xiaoou Li

Peter Lian

Andreas Molisch

Saeid Nahavandi

Jeffrey Reed

Diomidis Spinellis

Sarah Spurgeon

Ahmet Murat Tekalp

ARC FLASH HAZARD ANALYSIS AND MITIGATION

Second Edition

J.C. Das

Copyright © 2021 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.Published simultaneously in Canada.

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FOREWORD

As is common with emerging technologies, the maturity of safety considerations for a technology may lag the momentum in applying the technology. This has been true with the industrial, commercial, and residential electrification of modern society that began in the late nineteenth century. While human contact with electricity was known to be hazardous, differentiating arc flash from electric shock did not receive significant attention until a century later. We now know that injuries from arc flash events in electric power systems are among the most traumatic and costly occupational injuries. The intense energy transfer occurring in a fraction of a second converts electrical energy into thermal, blast, acoustic, chemical, and electromagnetic components that individually have their own injury consequences. Collectively, these energy transfers to the human body produce complex physical, neurological, and emotional trauma that are very difficult and costly to treat and rehabilitate. The resulting tragedy not only impacts the injured person, it extends to family, friends, and coworkers. And that is just the human side. Arc flash events also damage vital infrastructure, disrupting operations and damaging critical equipment. Altogether, the consequences in human suffering, equipment damage, and disruption of essential electrical systems can be extraordinary. But they can be prevented.

Increasing awareness of arc flash hazards has inspired improvements in administrative control measures, including safe work practices and application of personal protective equipment. These are important components of a comprehensive solution in reducing the risk of injury, but they have limitations. Administrative control measures are susceptible to human error that occur in real time with little opportunity for recovery from gaps in knowledge, misinterpretation of conditions, or lapse in discipline. Personal protective equipment for arc flash events is currently limited to thermal and acoustic hazards and may only reduce severity of injury as opposed to completely protecting the individual from injury. Injuries from the blast forces and respiratory harm from toxic chemicals and hot gases have been difficult to address with personal protective equipment. There is a more comprehensive answer, one that includes engineering solutions that reduce the potential for an arc flash event, minimize total energy transfer, and reduce the frequency of exposure.

Increasing awareness of arc flash events and consequences has generated research and publication across engineering, science, health and safety, medical, and legal disciplines. J.C. Das has researched this body of knowledge and brought together innovative ideas and practical concepts with abundant references and real world case studies in arc flash analysis and mitigation. For the first time, design engineers, facility managers, safety professionals, and operating and maintenance personnel have a comprehensive reference for prevention methods. Arc Flash Hazard Analysis and Mitigation provides a comprehensive set of tools to aid in the design, evaluation, and redesign of electric power systems. There is no single “silver bullet” for arc flash mitigation, yet following the methodology and analyses discussed in the book, professional engineers and power system designers can design new industrial electrical systems and modify existing systems to limit arc flash hazard incident energy to no more than 8cal/cm2. Chapter 15 of the book presents innovative ideas for arc flash analyses in DC systems. The analysis tools enable comparison of mitigating technologies and choices in system design to optimize arc flash risk for the life of the facility. For the workers at risk, the engineering solutions serve to automatically reduce risk and function independently of their knowledge, skills, and vulnerability to human error.

We are on a journey in arc flash mitigation. Ongoing basic research will continue to explore the complexities of the arc flash phenomena. Equipment manufacturers will introduce more innovative products to eliminate or reduce exposure. Protection engineers will refine methods to sense and interrupt faults faster. Reliability engineers will help address the problem of hidden failures in circuit protection hardware, software, and schemes. Facility engineers will become more knowledgeable in demanding prevention through design. Workers will be better protected from arc flash hazards. Arc Flash Hazard Analysis and Mitigation provides a roadmap. For the next worker at risk of a permanently disabling, life-changing arc flash injury, we need to accelerate our journey.

H. Landis “Lanny” Floyd

June 2012

H. Landis “Lanny” Floyd is Principal Consultant, Electrical Safety and Technology with DuPont. He is a fellow of IEEE and recipient of many awards, including the 2002 IEEE Richard Harold Kaufman award for advancing the development and application of electrical safety technology and the 2004 IEEE Medal for Engineering Excellence for contributions in arc flash analysis and mitigation. He has written more than 70 papers and articles on workplace electrical safety. He is also the Editor of the IEEE Industry Applications Magazine. He is a nationally and internationally recognized safety expert.

PREFACE TO SECOND EDITION

The authors and researchers all over the world expressed concerns on IEEE Guide 1584, 2002 methodology, test methods, and calculations of incident energy for arc flash hazard.

As a result, a joint venture by IEEE and NFPA was constituted. This addressed the concerns levied on 2000 edition of IEEE 584, and the 2018 edition is totally revised with respect to 2002 edition. This revision is being recognized all over the world. This second edition addresses the arc flash hazard calculations according to this revised edition. Major changes in concepts and methodology have occurred.

J.C. Das

PREFACE TO FIRST EDITION

The arc flash hazard analysis has taken the industry by storm, as evidenced by a spate of technical papers in the current literature, especially in IEEE Industry Application Society Petroleum and Chemical Industry, Industrial and Commercial Power Systems, Pulp and Paper Industry Technical Conferences, and the IAS Safety Workshop. The concerns of worker safety in electrical environment are making new strides with respect to equipment innovations, electrical system designs, and arc flash analysis and its mitigation. This impetus has attracted the attention of the industry to bring forward new product innovations, and it has challenged the expertise of practicing and consulting engineers to innovate electrical power system designs and relay protections. The current technical papers and literature address one or the other aspect of this subject. There is no comprehensive published work on this important subject.

This book fulfills this gap. All the aspects of arc flash hazard calculations, which include short circuits, protective relaying, differential relays, arc flash detection relays, relay coordination, grounding systems, arc resistant equipment, current transformer performance, and the like, are included in easy-to-understand language with a number of case studies, practical applications, and references. Current technologies and arc flash mitigation strategies, such as coordination on instantaneous basis, current limiting devices, zone interlocking, and equipment innovations, are covered. Appendix B provides tabulated statements for quick look up of arc flash hazards in electrical power systems. Chapter 13 is devoted to secondary protection of substation transformers because of its importance in arc flash hazard reduction. The critique of IEEE 1584 Guide methodology by various authors and improvements in safety culture and work ethics are discussed. A new algorithm for the calculation of arc flash hazard accounting for the decaying nature of the short-circuit currents, first presented in IEEE Industry Application Transaction papers by the author, is included.

The IEEE 1584 Guide does not cover arc flash hazard calculations in DC systems. Chapter 15 provides detailed short-circuit calculations in DC systems and then their applications to arc flash hazard calculations in DC systems. Chapter 16 discusses application of Ethernet and IEC 61850 communication protocols in a large industrial system for control, diagnostics, and data accessibility.

The book is written for practicing engineers, consultants, electrical power systems managers, and operating personnel. Some sections require undergraduate-level or higher knowledge of electrical power systems. The book should attract a wide readership due to the ever-increasing importance of this subject in recent times.

J.C. Das

ACKNOWLEDGEMENT

Special thanks go to the IEEE Standards Association for providing permission to use their content.

ABOUT THE AUTHOR

J.C. Das is currently President of Power System Studies, Inc. Earlier, he headed the Power System Analysis Department at Amec Foster Wheller, Inc., Tucker, GA, for 30 years. He is specialist in conducting power system studies, including short-circuit, load flow, harmonics, stability, arc flash hazard, grounding, switching transients, and protective relaying. His interests include power system transients, EMTP simulations, harmonics, power quality, protection, and relaying.

He has authored or coauthored about 70 technical publications, nationally and internationally and has published 200 study reports for real-world power systems for his clients. He is author of the books:

Power System Analysis, Second Edition, CRC Press, 2011; Transients in Electrical Systems, McGraw-Hill, 2010; Arc Flash Hazard Analysis and Mitigation (second edition under publication), IEEE Press, Hoboken, NJ, 2012. Power System Harmonics and Passive Filter Designs, IEEE Press, Hoboken, NJ, 2015; Understanding Symmetrical Components for Power System Modeling, IEEE Press, Hoboken, NJ, 2017; Power System Handbook in Four Volumes; Short-Circuit in AC and DC Systems, ANSI/IEEE and IEC Standards; Load Flow Optimization and Optimal Power Flow; Harmonic Generation Propagation and Control, Power System Protective Relaying, CRC Press, Boca Raton, FL, 2018.

Mr. Das is a member of the IEEE Industry Applications and IEEE Power Engineering Societies. He is a member of TAPPI and CIGRE, a Fellow of Institution of Engineering Technology (UK), a Life Fellow of the Institution of Engineers (India), and a Member of the Federation of European Engineers (France). He is registered Professional Engineer in the States of Georgia and Oklahoma, a Chartered Engineer (C. Eng.) in the UK, and a European Engineer (Eur. Ing.) in the Europe. Mr. Das received IEEE, Pulp and Paper Industry Committee meritorious award in Engineering in 2005.

His highest education qualification is a PhD in Electrical Engineering.

1 ARC FLASH HAZARDS AND THEIR ANALYSES

In the past, industrial electrical systems in the United States have been designed considering prevalent standards, that is, ANSI/IEEE, NEC, OSHA, UL, NESC, and the like, and arc flash hazard was not a direct consideration for the electrical system designs. This environment is changing fast, and the industry is heading toward innovations in the electrical systems designs, equipment, and protection to limit the arc flash hazard, as it is detrimental to the worker safety. This opens another chapter of the power system design, analysis, and calculations hitherto not required. There is a spate of technical literature and papers on arc flash hazard, its calculation and mitigation. References [1–8] describe arcing phenomena and arc flash calculations, sometimes commenting on the methodology of arc flash hazard calculations in IEEE Guide 1584 [9] (see Chapter 3).

These issues have become of great importance in the power system planning, designs and protective relay applications. “Safety by Design” is the new frontier (see Chapter 2).

Awareness of the various hazards caused by arc flash has increased significantly over the past decade. Arc flash is a dangerous condition associated with the unexpected release of tremendous amount of energy caused by an electric arc within electrical equipment [10]. This release is in the form of intense light, heat, sound, and blast of arc products that may consist of vaporized components of enclosure material—copper, steel, or aluminum. Intense sound and pressure waves also emanate from the arc flash, which resembles a confined explosion. Arcing occurs when the insulation between the live conductors breaks down, due to aging, surface tracking, treeing phenomena, and due to human error when maintaining electrical equipment in the energized state. The insulation systems are not perfectly homogeneous and voids form due to thermal cycling. In nonself restoring insulations, treeing phenomena starts with a discharge in a cavity, which enlarges over a period of time, and the discharge patterns resemble tree branches, hence the name “treeing” (Figure 1.1). As the treeing progresses, discharge activity increases, and, ultimately the insulation resistance may be sufficiently weakened and breakdown occurs under electrical stress. Treeing phenomena is of particular importance in XLPE (cross-linked polyethylene) and nonself restoring insulations. Surface tracking occurs due to abrasion, irregularities, contamination, and moisture, which may lead to an arc formation between the line and ground. An example will be a contaminated insulator under humid conditions. Though online monitoring and partial discharge measurements are being applied as diagnostic tools, the randomness associated with a fault and insulation breakdown are well recognized, and a breakdown can occur at any time, jeopardizing the safety of a worker, who may be in close proximity of the energized equipment. Arc temperatures are of the order of 35,000°F, about four times the temperature on the surface of the sun. An arc flash can therefore cause serious fatal burns.

Figure 1.1. Treeing phenomena in nonself-restoring insulation, leading to ultimate breakdown of insulation.

1.1 ELECTRICAL ARCS

Electrical arcing signifies the passage of current through what has previously been air. It is initiated by flashover or introduction of some conductive material. The current passage is through ionized air and the vapor of the arc terminal material, which has substantially higher resistance than the solid material. This creates a voltage drop in the arc depending upon the arc length and system voltage. The current path is resistive in nature, yielding unity power factor. Voltage drop in a large solid or stranded conductor is of the order of 0.016–0.033 V/cm, very much lower than the voltage drop in an arc, which can be of the order of the order of 5–10 V/cm of arc length for virtually all arcs in open air (Chapter 3