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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
A general overview of the use of utility distribution poles, including for electric supply and communications applications Overhead Distribution Lines: Design and Applications provides information on the design and use of power and communication distribution lines. An excellent resource for those in the power and communication utilities industry, this book presents information on the physical characteristics of utility poles, overhead supply and communication cables, installation practices, joint-usage issues, and safety rules, including the National Electrical Safety Code (NESC), California-specific rules, and others. It describes how to select the proper poles for specific applications. The especially valuable final chapter provides examples showing how it all works in practice, providing a background allowing more effective use of related industry software. Rather than delving into detailed design and installation techniques, this book serves as an overview for engineers and non-technical audiences alike. At the same time, it serves as a compendium of technical information not readily available elsewhere. This unique book: * Offers an overview of pole structures, pole installation and maintenance, wires and cables, and cable installation and maintenance--with examples * Provides information on national standards documents such as the National Electrical Safety Code (NESC), ANSI O5.1, California General Order 95, and more * Explores the "sag-tension" relationship between wires and poles * Includes appendices that cover properties of messenger strands, wireless attachments, solution of equations to determine sag, under uniform and point loads Overhead Distribution Lines: Design and Applications offers readers an understanding of the basic principles and various issues related to electric supply and communications distribution lines. It is a valuable resource for utility engineers, as well as those without a technical background.
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Seitenzahl: 179
Veröffentlichungsjahr: 2020
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Table of Contents
Cover
Title Page
Copyright
Dedication
About the Author
Preface
Acknowledgments
1 Introduction
1.1 Scope
1.2 Background
2 Pole Structures
2.1 General
2.2 Wood Pole Strength
2.3 Loads
2.4 Embedment Depth
2.5 Guying
2.6 Column Buckling
2.7 Grounding and Bonding
Notes
3 Pole Installation and Maintenance
3.1 Pole Placement
3.2 Guys and Anchors
3.3 Pole Maintenance
4 Wires, Conductors, and Cables
4.1 Categories
4.2 Messenger Wire/Strand
4.3 Electric Supply (Power) Cables
4.4 Communications Cables
4.5 Wireless Attachments
5 Cable Installation
5.1 Conductor and Cable Placement
5.2 Lashing Operation
5.3 Overlashing
Notes
6 NESC
®
Requirements (Strength and Loading)
6.1 National Electrical Safety Code (NESC)
6.2 Loading Requirements
6.3 Strength Requirements
6.4 Wire Tensions
6.5 Guyed Poles
6.6 Extreme Wind Loads (“60 ft Limit”)
6.7 Allowable Deterioration
6.8 Overlashed Cables
6.9 Software Tools and Pole Loading Analysis
Notes
7 NESC
®
Requirements (Clearances)
7.1 Clearances
7.2 Clearance Zones
7.3 Clearances Above Surfaces and Buildings
7.4 Clearances Between Wires
7.5 Overlashed Cables
Note
8 Principles of Wire Sag
8.1 Catenary
8.2 Initial and Final Sag
8.3 Sag–Tension Relationship
8.4 Determining Change in Sag (and Tension)
8.5 Ruling Span
8.6 Point Load
Note
9 General Order 95 (California)
9.1 General Order 95 (GO 95)
9.2 Loading Requirements
9.3 Strength Requirements
9.4 Clearances
10 Examples
10.1 Purpose
10.2 Tangent Line
10.3 Line Angle
10.4 Line Angle – Buckling Consideration
10.5 Additional Attachment
10.6 Summary
Note
Appendix A: Properties of Messenger Strands
Appendix B: Wireless Attachments
Appendix C: Extreme Wind and Extreme Ice Loadings
Appendix D: Solution of Cubic Equation
Note
Appendix E: Point Load
E.1 Parabolic Model
E.2 Intersecting Straight Lines Model
Glossary
References
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 Class loads for wood poles.
Chapter 6
Table 6.1 Rule 250B storm loadings.
Table 6.2 NESC load and strength factors for Rule 250B district loadings.
Chapter 7
Table 7.1 Prior storm loadings.
Table 7.2 Vertical clearances for typical distribution wires and cables (ft).
Chapter 9
Table 9.1 GO 95 storm loadings.
Appendix C
Table C.1 Rule 250C and 250D storm loadings.
Table C.2 NESC load and strength factors for Rule 250C and 250D extreme loads...
Table C.3 Rule 250D pressure vs. wind speed.
List of Illustrations
Chapter 1
Figure 1.1 Typical belowground construction.
Figure 1.2 Typical joint-use utility pole application.
Chapter 2
Figure 2.1 Distribution pole and associated hardware.
Figure 2.2 Basic pole load geometry (class loads).
Figure 2.3 Brand/mark on poles.
Figure 2.4 Wood pole strength variability.
Figure 2.5 Pole loadings.
Figure 2.6 Bending moment, including “
P
-delta” due to lateral deflection.
Figure 2.7 Guying.
Figure 2.8 Unbalanced load on pole resulting from wire tension.
Figure 2.9 Modes of column buckling (instability).
Chapter 3
Figure 3.1 Hole boring and pole placement.
Figure 3.2 Installation of lightweight pole.
Figure 3.3 Guy hook and sample application.
Figure 3.4 Guys and markers.
Figure 3.5 (a) Expansion anchor and (b) screw anchor.
Figure 3.6 Decay severity zones for wood utility poles.
Figure 3.7 Pole maintenance.
Figure 3.8 Inspected poles. (a) Pole with inspection tag and (b) rejected po...
Figure 3.9 Rehabilitated or reinforced poles.
Chapter 4
Figure 4.1 Steel messenger wire.
Figure 4.2 Use of hoops to support heavy communication cable.
Figure 4.3 Electric supply messenger.
Figure 4.4 Multiplex (quadruplex) cable.
Figure 4.5 Hendrix covered conductors.
Figure 4.6 Hendrix covered conductors.
Figure 4.7 Electric supply conductors. (a) AAAC and (b) ACSR/TW.
Figure 4.8 Typical metallic service drops.
Figure 4.9 Typical coaxial and fiber service drops.
Figure 4.10 Typical copper pair cables.
Figure 4.11 Jacketed and unjacketed coaxial cables.
Figure 4.12 All dielectric self-supporting fiber cable.
Figure 4.13 Wireless antennas mounted on utility poles. (a) Pole-top mountin...
Chapter 5
Figure 5.1 Stringing overhead communications cable – stationary reel method....
Figure 5.2 Stringing Hendrix-type supply cable – stationary reel method.
Figure 5.3 Stringing overhead communications cable – moving reel method.
Figure 5.4 Typical cable lasher.
Figure 5.5 Lashing communications cable – stationary reel method.
Figure 5.6 Stringing and lashing overhead communication cable – moving reel ...
Figure 5.7 Overlashed cable bundles.
Chapter 6
Figure 6.1 Storm loading districts for determining strength (Rule 250B).
Figure 6.2 Storm loading on ice-covered bundle.
Figure 6.3 Transverse loads applied to pole acting as a cantilever, resultin...
Figure 6.4 Strength factors applied to average strength of wood pole (Rule 2...
Figure 6.5 Conductor loads for determining wire tension.
Figure 6.6 Guy supporting storm load.
Figure 6.7 Comparison of transverse wind loads for multiple cables (Rule 250...
Figure 6.8 Incremental storm tension for multiple overlashed cables (Rule 25...
Chapter 7
Figure 7.1 Installed facilities.
Figure 7.2 Clearance zones for determining clearances.
Figure 7.3 Comparison of midspan sags for multiple overlashed cables under i...
Figure 7.4 Comparison of midspan sags for multiple overlashed cables at nomi...
Chapter 8
Figure 8.1 Comparison of hyperbolic and parabolic representations for suspen...
Figure 8.2 Non-level slope.
Figure 8.3 Inward movement of support point(s).
Figure 8.4 (a) Point load – peak sag occurs away from load. (b) Point load –...
Figure 8.5 Very heavy point load.
Chapter 9
Figure 9.1 Storm loading districts for California.
Chapter 10
Figure 10.1 Example pole with supply and communications lines.
Figure 10.2 Example pole at line angle supported by guys.
Figure 10.3 Example pole subject to vertical loads from guy tension.
Appendix E
Figure E.1 Point load vs. peak sag.
Guide
Cover Page
Table of Contents
Begin Reading
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IEEE Press445 Hoes LanePiscataway, NJ 08854
IEEE Press Editorial BoardEkram Hossain, Editor in Chief
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David Alan Grier
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Xiaoou Li
Peter Lian
Andreas Molisch
Saeid Nahavandi
Jeffrey Reed
Diomidis Spinellis
Sarah Spurgeon
Ahmet Murat Tekalp
Overhead Distribution Lines
Design and Application
Lawrence M. Slavin, PhD
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Library of Congress Cataloging-in-Publication Data
Names: Slavin, Lawrence M., author.
Title: Overhead distribution lines : design and application / Lawrence M. Slavin.
Description: Hoboken, NJ :Wiley, [2021] | Includes bibliographical references and index.
Identifiers: LCCN 2020031214 (print) | LCCN 2020031215 (ebook) | ISBN 9781119699132 (cloth) | ISBN 9781119699194 (adobe pdf) | ISBN 9781119699200 (epub)
Subjects: LCSH: Overhead electric lines–United States–Handbooks, manuals, etc. | Electric lines–Poles and towers–Handbooks, manuals, etc. | Telecommunication lines–United States–Handbooks, manuals, etc.
Classification: LCC TK3231 .S57 2021 (print) | LCC TK3231 (ebook) | DDC 621.319/22–dc23
LC record available at https://lccn.loc.gov/2020031214
LC ebook record available at https://lccn.loc.gov/2020031215
Cover design by Wiley
Cover image: © stevenfoley/Getty Images
I dedicate this book to two groups of people. First of all, to my wife, Helen, our children and their spouses, and, of course, our grandchildren, who are all quite special. I also dedicate this manual to the colleagues and friends that I have known and had the pleasure to work with over the past decades. I have had the good fortune of being able to continue to pursue my technical interests and activities into my “semi-retirement” years, while participating in professional organizations, as well as providing services on behalf of my clients, who have treated me with courtesy and respect.
About the Author
Dr. Lawrence (Larry) M. Slavin is Principal of Outside Plant Consulting Services, Inc. which was established in the year 2002 to help meet the needs of the telecommunications and power industries in establishing standards, guidelines, and practices for outside plant (outdoor) facilities and products. Larry has extensive experience and expertise in such activities, based upon his many years of service at AT&T/Lucent Bell Telephone Laboratories (Distinguished Member of Technical Staff) in telecommunications product design and development, followed by a career at Telcordia Technologies (now Ericsson, formerly Bellcore) in its research and professional service organizations. As Principal Consultant and Manager/Director of the Network Facilities, Components and Energy Group at Telcordia, he provided technical leadership in developing installation practices and “generic requirements” documents, introducing new construction methods, and performing analyses on a wide variety of technologies and products. Throughout his long career, Larry has had a leading role in the evolution of many telecommunications related fields and disciplines, for both overhead and belowground lines. Larry received his Bachelor's degree in mechanical engineering from The Cooper Union for the Advancement of Science and Art, and his Master's and PhD degrees from New York University. He lives with his wife, Helen, in White Meadow Lake in north central New Jersey.
Preface
This manual provides a general overview of the use of utility distribution poles for electric supply and communication applications. The intended audience includes utility engineers as well as those without a technical background, but who desire an understanding of the principles and various issues related to their application. The book is more an introduction to the subject than a detailed design, installation, or operations handbook and is not a replacement for the normal training and experiences typically required for either power or communications engineers responsible for the design, operation, and maintenance of overhead lines. This manual is a compendium of practical engineering and design information for poles and supported facilities, enhanced with some technical details that are not readily available elsewhere, that will prove to be helpful in some utility applications. The book is not intended to cover construction practices, which items are appropriately covered elsewhere, such as The Lineman's and Cableman's Handbook and the Telcordia Blue Book – Manual of Construction Procedures.
Information is provided on the physical characteristics of various types of utility poles, overhead supply and communication wires and cables, joint-use issues and related safety rules, including national standards and other related documents. The single most relevant document is the National Electrical Safety Code (NESC®), which is adopted or reflected in various regulations or industry practices throughout most of the United States and its territories. Other relevant documents include national standard ANSI O5.1 Wood Poles: Specifications and Dimensions and as well as various ASCE manuals, and documents produced by the Rural Utilities Service (RUS). The State of California is unique in that it has produced its own rules prescribed for overhead lines under the jurisdiction of its Public Utilities Commission, General Order No. 95 Rules for Overhead Electric Line Construction.
It was the original intention that this manual be published to include any new information contained in the upcoming (2022) edition of the NESC. However, the possible delayed availability of this edition, resulting from the COVID-19 pandemic, suggested that it would be more beneficial to base the manual on the current (2017) edition of the NESC, presented in a manner consistent with the publically available Pre-Print for the 2022 edition, rather than delay the publication of this manual. It is also recognized that, in most cases, based on the “grandfather” clause of the NESC, any new rules would only be applicable to newly constructed pole lines.
The information in this document is believed to be accurate at the time of its preparation, but is provided without any warranty, expressed or implied.
Lawrence M. Slavin, PhDNew York University, 1969
Acknowledgments
The author expresses his sincere appreciation to those that helped facilitate this publication, ranging from the courteous and efficient staff at Wiley-IEEE Press, and Ernesto Vega Janica at IEEE, to those that provided a technical review of this manual. In this regard, I particularly thank Trevor Bowmer and Dave Marne for their detailed formal review of the entire manual, which I recognize required a significant effort. I am also grateful to Martin Rollins, Andy Stewart, and Sam Stonerock for their review of specific portions of the manual. I consider myself fortunate to have colleagues that were willing to devote the extra time and energy, in addition to their many other obligations, to help me complete this project. However, any possible errors in the published document are my own responsibility, in spite of the best efforts of the reviewers.
1Introduction
1.1 Scope
This manual presents a brief description of typical practices for the design, installation, and usage of overhead utility distribution lines, providing an understanding of the basic principles, and facilitating the subsequent pursuit of the technology and issues in greater detail, as desired or appropriate. It is not, however, the intention of this document to provide or duplicate existing detailed design, construction, or installation specifications and information as presently employed by the various electric supply and communications utilities for their overhead facilities. Such information is available within the individual utilities or their representative organizations.
Although some of the information in this manual is applicable to a variety of overhead applications, including high-voltage transmission lines, the focus of the information is on the local distribution systems, closer to the customer or subscriber end of the grid. This portion of the network is typically characterized by efficient joint-use applications in which electric supply and communications facilities are in reasonably close proximity, supported on the same physical structures, but with strict rules and guidelines to help ensure reliable operation and the safety of both the public and the utility workers. These systems are characterized by significant variability between the facilities supported on each pole, and frequent changes based on customer need, and are generally not subject to the same level of physical design detail as the electrical transmission lines. Indeed, it would be neither practical nor cost-effective to perform a detailed, sophisticated structural analysis on every pole in a distribution line. In contrast, long-distance high-voltage power transmission facilities, along the same transmission line, are relative invariable and unchanging, with relatively uniform spans, and require the efforts of experienced structural engineers, often supported by the use of sophisticated software tools, to cost-effectively design reliable, safe overhead facilities.
This manual is divided into 10 sections or chapters. The background, including a description of the two general categories of construction methods relevant to outdoor utility lines, is provided in Chapter 1, including the overall characteristics and relative advantages and disadvantages represented by each category. Chapter 2 contains a description of pole structures and their physical characteristics, while Chapter 3 provides an overview of their installation, operation, and maintenance procedures. A description of the various types of suspended wires, conductors, and cables is contained in Chapter 4, and Chapter 5 discusses the methods of their installation. Chapters 6 (Strength and Loading) and 7 (Clearances) are primarily based on the rules of the National Electrical Safety Code (NESC®), which govern the physical design and construction of the overhead lines, to help ensure safe facilities for the public and utility workers. Chapter 8 explains the principles regarding wire sags (and related tensions) and provides methods for determining these values under various weather and operating conditions. Chapter 9 contains a brief description of General Order 95, which governs overhead utility lines in California, and how it compares to the NESC. Example calculations are included in Chapter 10 for estimating the physical status of pole systems subject to storm loads. Additional details and explanatory information supporting the various chapters is contained in Appendices A–E. A glossary of terms and a list of references are also provided.
1.2 Background
There are two basic modes of construction for outdoor utility lines for electric power supply and communication systems:
