Technical Report

Power System and Railroad ElectromagneticCompatibility Handbook

Revised First Edition

EPRI Project Manager B. Cramer

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 PO Box 10412, Palo Alto, California 94303-0813 USA

800.313.3774 650.855.2121 askepri@epri.com www.epri.com

Power System and Railroad Electromagnetic Compatibility Handbook Revised First Edition 1012652

Final Report, November 2006

Cosponsors Association of American Railroads (AAR) 50 F Street NW Washington DC 20001 Project Manager M. Congdon American Railway Engineering and Maintenance-of-Way Association (AREMA) 8201 Corporate Drive, Suite 1125 Landover, MD 20785 Project Manager I. Alperovich

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM:

(A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE; OR

(B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT.

ORGANIZATION(S) THAT PREPARED THIS DOCUMENT Timerider Technologies, Inc.

CorrComp

R.G. Olsen Consulting

ARC Technical Resources, Inc.

James Stewart Consulting

Union Switch and Signal

NOTE For further information about EPRI, call the EPRI Customer Assistance Center at 800.313.3774 or e-mail askepri@epri.com.

Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc.

Copyright 2006 Electric Power Research Institute, Inc. All rights reserved.

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CITATIONS

This report was prepared by:

Electric Power Research Institute (EPRI) 3420 Hillview Avenue Palo Alto, CA 94304

Principal Investigator B. Cramer

Timerider Technologies, Inc. 172 Summit Road Bishop, CA 93514 TimeriderTech@earthlink.net

Principal Investigator M. House

The authors of each chapter of this book are listed with the chapters.

This report describes research sponsored by EPRI, Oncor Energy Delivery Services, The National Grid Transco Company, Association of American Railroads (AAR), and American Railway Engineering and Maintenance-of-Way Association (AREMA).

The report is a corporate document that should be cited in the literature in the following manner:

Power System and Railroad Electromagnetic Compatibility Handbook: Revised First Edition. EPRI, Palo Alto, CA, Oncor Energy Delivery Services, Dallas, TX, The National Grid Transco Company, Warwick, UK, Association of American Railroads (AAR), NW, Washington DC and American Railway Engineering and Maintenance-of-Way Association (AREMA), Landover, MD: 2006. 1012652.

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PRODUCT DESCRIPTION

This book is a source of technology and information for preventing and mitigating ac electrical interference problems on railroads. All aspects of electromagnetic compatibility (EMC) where railroad systems are the receptors are examined. This includes well-understood areas such as magnetic induction from transmission lines as well as less understood areas such as conducted interference from distribution systems and effects of harmonics. Chapters examine all known effects of ac interference, including personnel safety, operation of railroad equipment and systems, and damage to railroad equipment. Direction is provided for studying the effects of proposed new and upgraded installations, as well as root cause analysis of problems on existing installations. The handbook is structured for use either as a reference, or for in-depth study. To date, information on these issues has been incomplete and scattered. The need for a single reference document exists for both the railroad and power industries. This handbook would not have been possible without a strategic alliance with the Association of American Railroads (AAR) and the American Railway Engineering and Maintenance-of-Way Association (AREMA). It is the hope of all those involved in electrical issues of joint corridors that this work will help facilitate safe, problem-free operation of railroads and power systems.

Results & Findings For the first time, one resource provides the tools necessary to understand and rectify ac interference problems on railroads. The tools provided can help personnel work backwards from effects to causes to find the best possible solutions. Savings can be significant. As several case studies demonstrate, problems that took weeks and months to track down can now be located in days or hours.

Challenges & Objectives This book is specifically written to be easily understood and useful for a variety of people responsible for the reliability of railroad and power systems. The intended audience includes railroad personnel, power company personnel, EMC specialists, and equipment suppliers. These groups include electrical engineers, mechanical engineers, technicians, signal maintainers, regulators, and managers. By preventing ac interference problems through advance planning, by tracking down existing problems more quickly, and by applying mitigation that is both effective and economical, substantial savings can result. Through continued study and handbook updates, even greater economic benefits can be expected. The continuing alliance between AAR, AREMA, and EPRI will help promote safe and reliable movement both for electric power and for passengers and freight, providing a high-degree of safety for the general public.

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Applications, Values & Use Periodic updates to this book will include developments in the railroad and power industries. Changes in signal systems and power systems have the potential to change the way these systems interact. By following the evolution of technology in future editions, this tool will continue to be effective.

EPRI Perspective EPRI is in a unique position to accomplish the goals described in this book. Our past joint projects with AAR, and our network of experts in power delivery and electromagnetic compatibility have provided many of the tools included in this handbook. With continued support from AAR and AREMA, an extensive network of railroad personnel, railroad equipment suppliers, and railroad consultants has been added to the mix. The result is a unique opportunity to produce a truly useful tool.

Approach The project teams first goal was to create a tool for solving any ac interference problem a railroad might experience and to do it in a way that any technician or engineer could apply. Another goal was to provide enough information to solve problems quickly while allowing for in-depth study.

Keywords joint corridors ac interference induction inductive coordination electromagnetic compatibility (EMC) electromagnetic interference (EMI) railroad signaling communication and signaling

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ABSTRACT

This book is intended as a source of technology and data for the prevention and mitigation of ac electrical interference problems on railroads. Much of the information was developed through joint projects between the Electric Power Research Institute (EPRI) and the Association of American Railroads (AAR) over the past thirty years, and by technical committees of the AAR and the American Railway Engineering and Maintenance-of-Way Association (AREMA). All aspects of electromagnetic compatibility where railroad systems are the receptors are examined. This includes well-understood areas such as magnetic and electric induction from transmission lines, as well as less well-understood areas such as conducted interference from distribution systems and the effects of harmonics. Chapters examine all known effects of ac interference, including safety of personnel, operation of railroad equipment and systems, and damage to railroad equipment. Direction is provided for the study of the effects of proposed new and upgraded installations, as well as root cause analysis of problems in existing installations. The handbook is structured to be used as both a quick reference book and for in-depth study.

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AUTHORS

Project Manager Editorial Committee Brian Cramer Irina Alperovich Ron Capan Mary Congdon Marvin Frazier Eddy Harrel Mike House Paul Jones Robert Olsen Mike Silva Robert Stevenson

Chapter 1: Introduction and Background Brian Cramer and Mike House

Chapter 2: Fundamentals of Electromagnetic Compatibility (EMC) Jerry Ramie and James Stewart

Chapter 3: Overview of Power Systems James Stewart and Brian Cramer

Chapter 4: Overview of Railroad Signal Circuits Mike House and Ben Feely

Chapter 5: Abnormal Operation of Railroad Equipment Mike House and Ben Feely

Chapter 6: Damage to Railroad Equipment Mike House

Chapter 7: Personnel Safety Considerations Brian Cramer and Marvin Frazier

Chapter 8: Field Measurements Mike House and Brian Cramer

Chapter 9: Investigation Mike House and Brian Cramer

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Chapter 10: Diagnostic Flow Chart Brian Cramer and Mike House

Chapter 11: Graphic Evaluation of Proposed Changes Based on Simulations Marvin Frazier

Chapter 12: Computer Modeling of Joint Corridors Marvin Frazier and Brian Cramer

Chapter 13: Mitigation Options Brian Cramer, Marvin Frazier, and Mike House

Chapter 14: Case Studies various contributors

Chapter 15: Planning Guidelines for New/Upgraded Railroad Systems Brian Cramer

Chapter 16: Planning Guidelines for New/Upgraded Power Systems Brian Cramer

Chapter 17: Conclusions Brian Cramer

Chapter 18: Glossary Mike Silva and Mike House

Chapter 19: Errata Sheet

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ACKNOWLEDGMENTS

In 1872 a patent was issued for electrical signaling apparatus for railroads. In 1893 commercial ac power transmission began in New York City. For most of the ensuing 110 years issues involving ac interference with railroad systems have been studied, debated, and mitigated with varying degrees of success. Expertise has been developed and forgotten several times during this period. And each new technology introduced has added another twist to the process of developing and maintaining compatible electrical systems. This Handbook is the result of the efforts of a great many people over a period of more than a century.

At the core of this effort are a handful of people who have struggled to bring two industries that use electricity in very different ways to a common understanding. These people share a passionate belief that by understanding all of the technologies involved, the issues can effectively be addressed. You will see these peoples names listed as authors and editors.

We thank the EPRI contractors who contributed their unique skill and technological ability. We also deeply appreciate the help of the EPRI utility participants who provided financial support.

We owe special thanks to the Association of American Railroads (AAR) and the American Railroad Engineering and Maintenance-of-Way Association (AREMA) for their participation and support. Much of the work in this field for the last dozen years has been done by these two organizations and by their technical committees. These industry committees, and the volunteers who participate on them, have made immeasurable contributions to this field. Much of the information collected in this book is the product of these organizations.

We would like to thank the members of the Project Advisory Committee (PAC). The PAC was tasked with keeping the Handbook on track. If the Handbook is the useful tool we envisioned, and if it is really understandable in its presentation, then the PAC deserves much of the credit. The PAC members are:

Irina Alperovich, Norfolk Southern Railroad (AREMA) Mary Congdon, Canadian Pacific Railroad (AAR) Eddy Harrel, Oncor Energy Delivery Services Paul Jones, Earthing Risk Management (National Grid Company)

The following individuals contributed photographs to the Handbook:

Peter Brackett, Canadian Pacific Railroad Ron Capan, Union Switch & Signal Ben Feely, Union Switch & Signal Michael Herz, Pacific Gas & Electric Company

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Mike House, Timerider Technologies Inc. Mike Silva, Enertech Dan Warren, Southern Company Dave Wright, Safetran Systems

The following individuals provided reviews and editorial support:

Irina Alperovich, Norfolk Southern Railroad Forrest Ballinger, GE Transportation Warwick Beech, Erico Richard Bowden, Burlington Northern Santa Fe Railroad Peter Brackett, Canadian Pacific Railroad Ron Capan, Union Switch & Signal Mike Choat, CSX Transportation Mary Congdon, Canadian Pacific Railroad John Danyluk, Comet Communications & Signal Ben Feely, Union Switch & Signal Marv Frazier, CorrComp Inc. Dave Gove, Transtector Eddy Harrel, Oncor Energy Delivery Services Mike House, Timerider Technologies Inc. Paul Jones, Earthing Risk Management Rod Leard, Saft America Bob MacMillan, CSX Transportation Fred Meeks, Burlington Northern Santa Fe Railroad Robert Olsen, Washington State University Jerry Ramie, ARC Technical Resources Mike Silva, Enertech Robert Stevenson, Consultant James Stewart, Consultant

Brian S Cramer EPRI Palo Alto, California

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HOW TO USE THIS HANDBOOK

Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are complex fields of study. EMC work is often further complicated when the source of the interference and the receptor of the interference are very different technologies. Railroads and power systems are an example of this. While both industries have thousands of knowledgeable people, including a great many electrical engineers, few of them understand both industries.

This handbook is specifically organized to fill this void. To achieve this goal, most chapters have been organized into three sections. They are:

Introduction Quick-Start Version

The quick-start version of each chapter is designed to allow the user to work effectively in the shortest time. It is possible to read the quick-start version of each relevant chapter and to begin to address a problem. Of course, the effectiveness of this method will depend on the users prior knowledge and experience.

Detailed Version For those with a thirst for greater knowledge, and the time to satisfy it, read the detailed version of each chapter. In the end, this will benefit both you and your organization.

It is highly recommended that every user read the detailed section of Chapter 2: Fundamentals of Electromagnetic Compatibility. A basic understanding of this field of study is necessary. The next thing to read is the chapter about the other industrys system. For example, if you are a power engineer, read Chapter 4: Overview of Railroad Signal Circuits preferably the detailed version. If you are a railroader, then we recommend you read Chapter 3: Overview of Power Systems. To effectively address interference issues, you need an understanding of EMC fundamentals and the basics of all systems involved.

Throughout this handbook the authors and editors have tried to make each chapter and section stand-alone. You will see terms and acronyms defined repeatedly. This is done so the user can use the handbook as a reference with a minimum of flipping back and forth to fill gaps. Never the less, an extensive glossary is provided with both power and railroad terms.

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CONTENTS

1 INTRODUCTION AND BACKGROUND ................................................................................1-1 Background ...........................................................................................................................1-2 What is AC Power Interference?...........................................................................................1-4 Prior Programs ......................................................................................................................1-5 Terminology...........................................................................................................................1-6 Organization..........................................................................................................................1-7 References............................................................................................................................1-8

2 FUNDAMENTALS OF ELECTROMAGNETIC COMPATIBILITY (EMC) ..............................2-1 Introduction ...........................................................................................................................2-2 Quick-Start Version ...............................................................................................................2-2

Introduction to EMC..........................................................................................................2-2 Detailed Version....................................................................................................................2-4

Introduction to EMC..........................................................................................................2-4 Interference Paths ............................................................................................................2-6 Differential and Common Mode Signal Types ................................................................2-15

Differential Mode Signal.............................................................................................2-16 Common Mode Signal ...............................................................................................2-17

Interference Types..........................................................................................................2-18 Common Mode Interference ......................................................................................2-18 Differential Mode Interference....................................................................................2-19 Receptor Circuit Unbalance.......................................................................................2-21

European and North American Models ..........................................................................2-23 European Model ........................................................................................................2-23 North American Model ...............................................................................................2-24

Personnel Safety ............................................................................................................2-25 Emissions & Immunity Testing .......................................................................................2-25 Types of Emissions Tests...............................................................................................2-26

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Types of Immunity Tests ................................................................................................2-26 Immunity Performance ...................................................................................................2-27 Regulatory Structure.......................................................................................................2-27 Basic EMC Standards ....................................................................................................2-28 EMC Standards in other Industries.................................................................................2-28 Legal Environments........................................................................................................2-31 Social Environments.......................................................................................................2-31 Addressing the gaps.......................................................................................................2-32 Summary ........................................................................................................................2-33

Railways Need To:.....................................................................................................2-33 Power Providers Need To:.........................................................................................2-33 Railway Signal Equipment Manufacturers need to: ...................................................2-34

References..........................................................................................................................2-34

3 OVERVIEW OF POWER SYSTEMS......................................................................................3-1 Introduction ...........................................................................................................................3-2 Quick-Start Version ...............................................................................................................3-2

Introduction to the Power System.....................................................................................3-2 Detailed Version....................................................................................................................3-4

Introduction to the Power System.....................................................................................3-4 Overhead Transmission Lines..........................................................................................3-8 Underground Transmission Lines...................................................................................3-12 Overhead Distribution Lines ...........................................................................................3-13

Primary Feeder Grounding ........................................................................................3-15 4-Wire Multi-Grounded Feeders............................................................................3-16 4-Wire Single-Point Grounded Feeders ................................................................3-17 3-Wire Ungrounded Feeders.................................................................................3-17 3-Wire Grounded (Unigrounded) Feeders ............................................................3-19 5-Wire Feeders .....................................................................................................3-20 Other Systems ......................................................................................................3-20

Secondary Feeder Grounding....................................................................................3-21 Other Considerations Related to Ground Currents....................................................3-22 Impact on EMC ..........................................................................................................3-23 Substations Near Railroad Tracks .............................................................................3-23

Underground Distribution Lines ......................................................................................3-24

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Secondary Distribution ...................................................................................................3-25

4 OVERVIEW OF RAILROAD SIGNAL CIRCUITS ..................................................................4-1 Introduction ...........................................................................................................................4-2 Quick-Start Version ...............................................................................................................4-2 Detailed Version....................................................................................................................4-3

Railroad Signaling Circuits Introduction.........................................................................4-3 Railroad Track Part of the Track Circuit ........................................................................4-4 Railroad Rails and Ties Mechanical and Electrical Properties ......................................4-5

Railroad Tracks............................................................................................................4-6 Ballast.............................................................................................................................4-13 Contaminants in Ballast..................................................................................................4-15 Railroad Track as an Electrical Transmission Line.........................................................4-16 Bondwires.......................................................................................................................4-17 Rails................................................................................................................................4-20 The Shunting Action of a Trains Axles...........................................................................4-20 Insulated Joints...............................................................................................................4-25 Insulated Joint Failure Modes.........................................................................................4-29 Track Circuits..................................................................................................................4-31 What Is (and What Isnt) a Track Circuit?.......................................................................4-31 Robinsons Patent ..........................................................................................................4-32 Railroad History ..............................................................................................................4-37 General Types of Signal Equipment...............................................................................4-38 What is a Signal System?...............................................................................................4-39 Signaled vs. Non-Signaled Trackage .............................................................................4-40

Signaled Trackage and its Signal Systems................................................................4-41 Signal Systems: Wayside Signals and Cab Signals.......................................................4-41 What is a Block?.............................................................................................................4-43 Signaling Basics .............................................................................................................4-44 What is an Interlocking? .................................................................................................4-45

Mechanical Interlocking .............................................................................................4-47 Power Interlocking .....................................................................................................4-47 Relay-Based Interlocking...........................................................................................4-48 Solid-State Interlocking..............................................................................................4-49

Types of Signaling Systems ...........................................................................................4-50

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Wayside Signal Aspects and Indications........................................................................4-50 Colorlight Signals.......................................................................................................4-52 Crossing Flashers......................................................................................................4-53 LED Colorlight Signals...............................................................................................4-54 Searchlight Signals ....................................................................................................4-55 Fiber-Optic Searchlight Signals .................................................................................4-56 Position Light Signals ................................................................................................4-56 Semaphore Signals ...................................................................................................4-56 Signal Lighting Circuits ..............................................................................................4-57 Signal Lamps .............................................................................................................4-57

Cab Signal Systems .......................................................................................................4-58 Types of Signal Control Systems ...................................................................................4-58

Automatic Block Signals (ABS)..................................................................................4-58 Absolute-Permissive Block Signaling (APBS)............................................................4-60 Centralized Traffic Control (CTC) ..............................................................................4-61 Train Control Systems ...............................................................................................4-63 Mechanical Trip Stop .................................................................................................4-64 Intermittent Inductive Trip Stop..................................................................................4-65 Indusi .........................................................................................................................4-66 Magnetic Trip Stop.....................................................................................................4-66

Communications-Based Train Control (CBTC) ..............................................................4-67 Track Circuits in General ................................................................................................4-68 Batteries and Electrification ............................................................................................4-69 Primary Batteries ............................................................................................................4-70 Rechargeable Batteries ..................................................................................................4-71 Transmitters....................................................................................................................4-72 Receivers Correct Reception is the Key to Safety.......................................................4-74 The Output of the Track Circuit ......................................................................................4-77 Shunting .........................................................................................................................4-78 Remedies for Poor Shunting ..........................................................................................4-82 Railroad Track Circuits One at a Time ........................................................................4-83

Steady Energy DC Track Circuits ..............................................................................4-83 Polarized DC Track Circuits.......................................................................................4-86 Coded DC Track Circuits ...........................................................................................4-87

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Trakode......................................................................................................................4-89 PMTC (Pulse-Modulated Track Circuit) .....................................................................4-90 Electro Code ..............................................................................................................4-91 Electrified Electro Code .............................................................................................4-92 Microtrax ....................................................................................................................4-93 AC Track Circuits In General ..................................................................................4-94 Classic AC Track Circuits ..........................................................................................4-94 Double Element Vane Relays....................................................................................4-96 Phase Shifting............................................................................................................4-97 Centrifugal AC Relays................................................................................................4-97 Single-Rail Vane-Relay AC Track Circuits.................................................................4-98 Double-Rail AC Vane-Relay Track Circuits and Impedance Bonds ........................4-100 All-AC Signaling Systems ........................................................................................4-103 Style C Track Circuits ..............................................................................................4-104 Audio-Frequency Track Circuits...............................................................................4-105 Audio-Frequency Overlay ........................................................................................4-107 Impulse Track Circuits .............................................................................................4-109 Cab Signals .............................................................................................................4-109 Audio-Frequency Cab Signaling............................................................................4-112 Grade Crossings......................................................................................................4-113

Crossing Predictors.............................................................................................4-114 Motion Sensors ...................................................................................................4-117

Motion Sensors, Crossing Predictors, and AC Interference .........................................4-118 Conventional or Stick Grade Crossing Warning Systems ................................4-120 Highway Crossing Gate Mechanisms .................................................................4-121 Highway Crossing Flashers ................................................................................4-123 Crossing Bells .....................................................................................................4-124

Highway Crossing Traffic Preemption......................................................................4-125 Alternatives to Track Circuits........................................................................................4-126

Communication-Based Crossing Warning Systems ................................................4-126 Magnetometers........................................................................................................4-127 Wheel Detectors ......................................................................................................4-127 Axle Counters ..........................................................................................................4-128 Global Positioning Systems .....................................................................................4-128

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Hazard Detectors..........................................................................................................4-130 Wheel Defect Detectors...........................................................................................4-131 Hotbox Detectors .....................................................................................................4-131 Slide Fences ............................................................................................................4-131 Tag Readers ............................................................................................................4-132 End-of-Train Monitoring (E.O.T.M.) .........................................................................4-133

Other Miscellaneous Track-Mounted Signal Equipment ..............................................4-134 Gauge Plates and Gauge Rods...............................................................................4-134 Switch Circuit Controllers.........................................................................................4-136 Electric Switch Locks ...............................................................................................4-137 Switch Machines......................................................................................................4-138 Impedance Bonds....................................................................................................4-141

Other Signaling Topics .................................................................................................4-146 Electric Traction Circuits ..........................................................................................4-146 Safety, Vitality, and Fail-Safe Design.......................................................................4-149 Rules, Standards and Instructions...........................................................................4-153 Lightning Protection and Grounding ........................................................................4-154 AC Interference Issues ............................................................................................4-157

References........................................................................................................................4-160

5 ABNORMAL OPERATION OF RAILROAD EQUIPMENT ....................................................5-1 Introduction ...........................................................................................................................5-2 Quick-Start Version ...............................................................................................................5-2 Detailed Version....................................................................................................................5-2

Abnormal Operation of Railroad Signal Equipment..........................................................5-2 Definitions, Terminology, and Philosophy....................................................................5-3 Redundancy vs. Vitality ...............................................................................................5-5 Dual vs. Vital ................................................................................................................5-6 Abnormal Operation.....................................................................................................5-7

Wrong-Side Abnormal Operation..........................................................................5-7 Right-Side Abnormal Operation............................................................................5-9 Abnormal Operation from Spoofing of Normal Events........................................5-11

Philosophy .................................................................................................................5-12 Methods of Achieving Vitality .....................................................................................5-13 Vitality and Creative Equipment Maintenance.........................................................5-14

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Rules, Vitality, and Wrong-Side Failures ...................................................................5-15 Railroad Signal Equipment Standards vs. Other Industries.......................................5-16

6 DAMAGE TO RAILROAD EQUIPMENT................................................................................6-1 Introduction ...........................................................................................................................6-2 Quick-Start Version ...............................................................................................................6-2 Detailed Version....................................................................................................................6-2

Standards .........................................................................................................................6-3 Railroad Signal Equipment Design Practices ...................................................................6-5 Exposures.........................................................................................................................6-7 Mitigation ..........................................................................................................................6-9

7 PERSONNEL SAFETY CONSIDERATIONS.........................................................................7-1 Introduction ...........................................................................................................................7-2 Quick-Start Version ...............................................................................................................7-2

Shock Hazard ...................................................................................................................7-2 Electric Induction .........................................................................................................7-2 Magnetic Induction.......................................................................................................7-2

Fault Induced Voltages.....................................................................................................7-3 Electric and Magnetic Field Exposure ..............................................................................7-3

Detailed Version....................................................................................................................7-4 Shock Hazard ...................................................................................................................7-4

Background..................................................................................................................7-4 Duration of Exposure ...................................................................................................7-6 Steady-State Exposure................................................................................................7-6 Short Duration Exposure..............................................................................................7-7 Philosophy of Setting Standards..................................................................................7-9

Usual Circumstances ............................................................................................7-11 Steady-State Limits....................................................................................................7-12

Body/Contact Impedance......................................................................................7-12 Conductor Circuit Impedance................................................................................7-14 Source Impedance ................................................................................................7-14 Voltage Limits Derived From Current Effects........................................................7-16 Other Considerations ............................................................................................7-16 Possible Target Values .........................................................................................7-18

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Limits for Faults and other Short-Duration Events .....................................................7-20 Possible Target Values .........................................................................................7-23

Electric and Magnetic Field Standards and Guidelines ..................................................7-23 Introduction to Standards and Guidelines..................................................................7-23 State Standards and Recommendations Related to Transmission Lines..................7-23 Guidelines for Exposure to 50/60 Hz Electric and Magnetic Fields ...........................7-25 International Standards..............................................................................................7-27 Swedish Standards for Computers and Monitors ......................................................7-29

Safe Working Clearances from Power Lines..................................................................7-30 References..........................................................................................................................7-32

8 FIELD MEASUREMENTS ......................................................................................................8-1 Introduction ...........................................................................................................................8-2 General Precautions for all Test Procedures ........................................................................8-2 Tests .....................................................................................................................................8-3 General Information...............................................................................................................8-4

Test #1 Excessive Common Mode Voltage...................................................................8-7 Objectives ....................................................................................................................8-7 Overview......................................................................................................................8-7 Equipment Required ....................................................................................................8-7 Procedure ....................................................................................................................8-7 Interpretation of Measurements ...................................................................................8-8

First Discriminant: Rail-to-Ground Voltage Magnitude............................................8-8 Second Discriminant: Rail-to-Ground Voltage Magnitude.......................................8-8

Test #2 Measure Dominant Frequency .......................................................................8-10 Objectives ..................................................................................................................8-10 Overview....................................................................................................................8-10 Equipment Required ..................................................................................................8-10 Procedure ..................................................................................................................8-10 Interpretation of Measurements .................................................................................8-12

First Discriminant: Rail-to-Ground Voltage Magnitude..........................................8-12 Second Discriminant: Dominant Frequency..........................................................8-12

Test #3 Check for Excessive Track Circuit Unbalance................................................8-13 Objectives ..................................................................................................................8-13 Overview....................................................................................................................8-13

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Equipment Required ..................................................................................................8-13 Procedure ..................................................................................................................8-13 Interpretation of Measurements .................................................................................8-15

First Discriminant: Degree of Track Circuit Unbalance .........................................8-15 Test #4 - Spectral Analysis Test.....................................................................................8-16

Objective....................................................................................................................8-16 Overview....................................................................................................................8-16 Equipment Required ..................................................................................................8-16 Procedure ..................................................................................................................8-16 Interpretation..............................................................................................................8-17

First Discriminant: Ratio of AC Power Fundamental to First Odd Harmonic.........8-17 Second Discriminant: Fundamental to First Even Harmonic Ratio .......................8-18 Third Discriminant: Power and Proximity to Motion Sensor or Crossing Predictor Operating Frequency .............................................................................8-18

Test #5 Coarse Rail Balance Test...............................................................................8-20 Objectives ..................................................................................................................8-20 Overview....................................................................................................................8-20 Equipment Required ..................................................................................................8-20 Procedure ..................................................................................................................8-20 Interpretation of Measurements .................................................................................8-22

First Discriminant: Rail-to-Rail Voltage Magnitude................................................8-22 Second Discriminant: Rail-to-Ground Voltage Magnitude.....................................8-22 Third Discriminant: Rail-to-Ground Voltage Magnitude.........................................8-22 Fourth Discriminant: Rail-to-Ground Voltage Balance ..........................................8-22 Fifth Discriminant: Voltage Summation .................................................................8-23

Test #6 Rail-Rail and Rail-Ground Spatial Voltage Distribution Test ..........................8-24 Objective....................................................................................................................8-24 Overview....................................................................................................................8-24 Equipment Required ..................................................................................................8-24 Procedure ..................................................................................................................8-24 Interpretation..............................................................................................................8-26

First Discriminant: Rail-to-Ground Voltage............................................................8-27 Second Discriminant: Rail-to-Rail Voltage ............................................................8-27 Third Discriminant: Rail-to-Ground Voltage Anomalies.........................................8-27

Test #7 Insulated Joint Test ........................................................................................8-28

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Objective....................................................................................................................8-28 Overview....................................................................................................................8-28 Equipment Required ..................................................................................................8-29 Procedure ..................................................................................................................8-30 Interpretation..............................................................................................................8-32

Test #8 Direct Measurement of Insulated Joint Resistance ........................................8-34 Objective....................................................................................................................8-34 Overview....................................................................................................................8-34 Equipment Required ..................................................................................................8-34 Procedure ..................................................................................................................8-34 Interpretation..............................................................................................................8-35

Test #9 Alternate Insulated Joint Test No Special Equipment .................................8-38 Objective....................................................................................................................8-38 Overview....................................................................................................................8-38 Equipment Required ..................................................................................................8-38 Procedure ..................................................................................................................8-38 Interpretation..............................................................................................................8-39

Test #10 Arrester/Equalizer Test.................................................................................8-40 Objective....................................................................................................................8-40 Overview....................................................................................................................8-40 Equipment Required ..................................................................................................8-40 Procedure ..................................................................................................................8-41 Interpretation..............................................................................................................8-42

Test #11 Hardwire Shunt Testing ................................................................................8-43 Objective....................................................................................................................8-43 Overview....................................................................................................................8-43 Equipment Required ..................................................................................................8-43 Procedure ..................................................................................................................8-44 Interpretation..............................................................................................................8-44

Test #12 Local Ground/Power Company Neutral Isolation Test .................................8-45 Objective....................................................................................................................8-45 Overview....................................................................................................................8-45 Equipment Required ..................................................................................................8-45 Procedure ..................................................................................................................8-45

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Interpretation..............................................................................................................8-46

9 INVESTIGATION ....................................................................................................................9-1 Introduction ...........................................................................................................................9-2 Quick-Start Version ...............................................................................................................9-2

Troubleshooting Fundamentals The Scientific Method .................................................9-2 Step 1): Recognition A Report of a Problem .................................................................9-2 Step 2): Study the Problem ..............................................................................................9-3 Step 3): Guess at the Cause(s) ........................................................................................9-3 Step 4): Predict the Implications.......................................................................................9-4 Step 5): Test Each Implication..........................................................................................9-4 Step 6): Form the Simplest Theory that Explains the Results ..........................................9-4 Is it Really AC Interference?.............................................................................................9-4 The Rules of Thumb of Railroad Signals and AC Interference ......................................9-5

Detailed Version....................................................................................................................9-5 Introduction.......................................................................................................................9-5 The Nature of the Problem ...............................................................................................9-6 Troubleshooting Fundamentals The Scientific Method .................................................9-7

Recognizing AC Interference Problems.......................................................................9-7 Step 1): Recognition A Report of a Problem .................................................................9-9 Step 2): Study the Problem ............................................................................................9-10 Step 3): Guess at the Cause(s) ......................................................................................9-11 Step 4): Predict the Implications.....................................................................................9-12 Step 5): Test Each Implication........................................................................................9-13 Step 6): Form the Simplest Theory that Explains the Results. .......................................9-14 A Hidden Fork in the Road .............................................................................................9-15 The Source Path Receptor Model ............................................................................9-16 The Rules of Thumb of Railroad Signals and AC Interference ....................................9-17 The Questions ................................................................................................................9-20

The What Questions................................................................................................9-20 The Where Questions..............................................................................................9-21 The When Questions...............................................................................................9-22 Guessing at the Causes.............................................................................................9-23 The Specific Questions..............................................................................................9-24

Common Sources for E.M. Fields Power Lines...........................................................9-24

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Common Sources for Conducted Interference ...............................................................9-25 Common Paths Fields, Rails, and Wires .....................................................................9-25 Common Receptors Motion Sensors and Crossing Predictors ...................................9-27

Motion Sensors and Crossing Predictors Symptoms and What They Mean ..........9-27 Case #1: The Crossing Equipment is Activated Continuously or Intermittently When there are No Trains Around ........................................................................9-28 Case #2: The Crossing Equipment is Activated Before it should be, but there is a Train Approaching ..........................................................................................9-31 Case #3: The Crossing Equipment Stays Activated for Longer than it should after a Train has Passed Completely through the Grade Crossing.......................9-33 Case #4: The Crossing Equipment is Activated Briefly after a Train has Passed Completely Through the Grade Crossing and the Crossing has Recovered.............................................................................................................9-33

10 DIAGNOSTIC FLOW CHART ............................................................................................10-1 Introduction .........................................................................................................................10-2 Following the Flow Chart.....................................................................................................10-3

Where to begin ...............................................................................................................10-3 How to Proceed ..............................................................................................................10-3

11 GRAPHIC EVALUATION OF PROPOSED CHANGES BASED ON SIMULATIONS.......11-1 Introduction .........................................................................................................................11-2 Summary of Graphical Aids for Compatibility Issues ..........................................................11-2

Personnel Safety for Steady State Magnetic Field Induction to Rails ............................11-7 Signal System Equipment Compatibility for Steady State Magnetic Field Induction to Rails..........................................................................................................................11-10 Personnel Safety for Steady State Electric Induction to Open Wire Signal Pole Lines .............................................................................................................................11-13 Personnel Safety for Faulted Power-Line Magnetic Field Induction to Rails ................11-13 Power-Line Fault Induced Rail Current for Lightning Arrester Survival ........................11-14

Example of Preliminary Compatibility Assessment by Graphical Procedures...................11-15 Introduction and Background........................................................................................11-15

Preliminary Review of Coupled Voltage and Current...............................................11-16 Steady State Coupling to Track ..........................................................................11-16 Steady State Coupling to Pole Line ....................................................................11-19 Fault Current Coupling to Track ..........................................................................11-19

Conclusions .............................................................................................................11-20

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12 COMPUTER MODELING OF JOINT CORRIDORS...........................................................12-1 Introduction .........................................................................................................................12-2 Quick-Start Version .............................................................................................................12-2

What Computer Modeling Will and Will Not Do ..............................................................12-2 General...........................................................................................................................12-2 Required Information ......................................................................................................12-3 Results............................................................................................................................12-7 Choosing a Consultant ...................................................................................................12-8 Choosing Software .........................................................................................................12-8

Detailed Version..................................................................................................................12-8 Overview of Power System-Railroad Interactions ..........................................................12-8 Power Systems Steady State Magnetic Field for Railroad Compatibility Studies...........12-9

Quantifying Magnetic Field Coupling .........................................................................12-9 Three-Phase Systems .............................................................................................12-14 Unbalance Comparison Example ............................................................................12-19 More on Power Line Unbalance...............................................................................12-20 Conservative Effect of Steady State Unbalance Example ......................................12-21 Double Circuit Arrangements...................................................................................12-22

Steady State Compatibility Modeling of Railroad Systems for Magnetic Field Coupling from Power Systems .....................................................................................12-25

Track Signal Circuits and Their Effect on Induced Voltage......................................12-25 Track Unbalances and Induced Voltage at Signal Equipment .....................................12-34

Degraded IJ and Track Unbalance ..........................................................................12-42 Shorted IJ Example.............................................................................................12-46 Field Measurements............................................................................................12-47 Analysis of Exposure...........................................................................................12-51 Model Comparison to Field Measurements ........................................................12-51 Power-System Phasing.......................................................................................12-54

Degraded IJ with Train.............................................................................................12-55 Field-Measured Example ....................................................................................12-56 Simple Model with Shorted Insulator...................................................................12-58

Signal Equipment Impedance..................................................................................12-61 Shorted Arrester to Ground......................................................................................12-63

Affect of Signal-System Ground Resistance on Coupled Interference ...............12-64 Conduction Coupling to Track Circuit..................................................................12-67

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Analysis Procedure for Evaluating Induced Voltage at Track Signal Equipment.....12-69 Susceptibility of Track Signal Equipment.................................................................12-71

Steady State Coupling to Railroad Signal Lines...........................................................12-71 Magnetic Field Coupling to Signal Lines..................................................................12-71 Electric Induction Coupling to Signal Lines Concepts...........................................12-72 Electric Induction Coupling to Signal Lines Example............................................12-76

Power Line Fault Coupling to Railroad System ............................................................12-83 Overview..................................................................................................................12-83 Fault-Induced Firing of Track Arresters ...................................................................12-84

The Firing of Arresters in One Track Circuit........................................................12-85 The Firing of Arresters in Adjacent Track Circuits...............................................12-86

Fault-Induced Rail Current.......................................................................................12-90 Fault-Induced Rail Voltage and Personnel Safety ...................................................12-95

References......................................................................................................................12-100

13 MITIGATION OPTIONS......................................................................................................13-1 Introduction .........................................................................................................................13-3 Mitigation Tables .................................................................................................................13-3 Detailed Options..................................................................................................................13-7

Power System Mitigation ................................................................................................13-7 Counterpoise Underground.....................................................................................13-7 Counterpoise Aerial ................................................................................................13-8 Fault Current Limiting.................................................................................................13-8 Load Current Limiting.................................................................................................13-9 Phase Arrangement Optimization (Cancellation).......................................................13-9 Split-Phasing............................................................................................................13-10 Neutral Wire Size Increase ......................................................................................13-10 Phase Current Balance Optimization.......................................................................13-11 Phase Spacing reduction (Phase Compaction) .......................................................13-12 Vertical Spacing Increase (Higher Structures).........................................................13-12 Horizontal Spacing Increase....................................................................................13-13 Automatic Reclosing Restriction ..............................................................................13-13 Manual Reclosing Restriction ..................................................................................13-14 Fault Current Clearing Time Reduction ...................................................................13-14 Open Delta Transformer Removal ...........................................................................13-15

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Capacitor Bank Inspection/Monitoring .....................................................................13-15 Railroad Mitigation........................................................................................................13-16

Reducing Length of Electrically Continuous Track (At Power Frequencies) (Shorten Track Blocks) ............................................................................................13-16 Counterpoise Underground...................................................................................13-16 Grounding Un-Signaled Track/Sidings (Multigrounded Rail can Act as a Counterpoise) ..........................................................................................................13-17 Insulated Joint Inspection Increased.....................................................................13-18 Insulated Joint Replacement-Shorted or Leaky Units..............................................13-18 Surge Arresters Inspection Increased...................................................................13-19 Surge Arresters Replacement Failed Units...........................................................13-20 By-Pass Shunts And Couplers Removal .................................................................13-21 Resistive Network Installation..................................................................................13-21 Isolation Transformer Installation.............................................................................13-22 Work Gloved (Work Using Electrically Insulated Rated Gloves.).............................13-22 Track Circuit Balance Optimization..........................................................................13-23 Battery Chargers Supplied at 240 Volts...................................................................13-23 Track Circuit Lead Fusing........................................................................................13-24 Operating Frequencies Chosen to Maximize Immunity ...........................................13-25 Signal Output Level Increases.................................................................................13-26 Equipment Replaced with Less Susceptible Equivalent Systems ...........................13-27 Pole-Line Communication Systems Removed.........................................................13-27 Style C Track Circuits Removed............................................................................13-28 60 Hz Cab Signals Changed to Another Frequency................................................13-29 Railroad Bed (Ballast) Condition Improvement........................................................13-29 Ground Mats/Grids Around Equipment....................................................................13-30

Safe Working Clearances from Power Lines................................................................13-31

14 CASE STUDIES .................................................................................................................14-1 Introduction .........................................................................................................................14-1 Excessive Common Mode Voltage .....................................................................................14-2

Case Study #1 ................................................................................................................14-2 Case Study #2 ................................................................................................................14-4 Case Study #3 ................................................................................................................14-6

Equipment Damage from Power System Events ................................................................14-7

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Case Study #4 ................................................................................................................14-7 Case Study #5 ................................................................................................................14-8 Case Study #6 ................................................................................................................14-9 Case Study #7 ..............................................................................................................14-10

Steady-State Effects to Equipment Operation...................................................................14-11 Case Study #8 ..............................................................................................................14-11 Case Study #9 ..............................................................................................................14-12 Case Study #10 ............................................................................................................14-14 Case Study #11 ............................................................................................................14-15 Case Study #12 ............................................................................................................14-16 Case Study #13 ............................................................................................................14-17

15 PLANNING GUIDELINES FOR NEW/UPGRADED RAILROAD SYSTEMS.....................15-1 Introduction .........................................................................................................................15-2 Quick-Start Version .............................................................................................................15-2 Detailed Version..................................................................................................................15-4

Sources ..........................................................................................................................15-4 Paths ..............................................................................................................................15-5

Distance.....................................................................................................................15-5 Block Length, Wideband Shunts, and Tuned Couplers .............................................15-6 Ballast ........................................................................................................................15-6

Receptors .......................................................................................................................15-7 Steady-State...................................................................................................................15-8 Fault................................................................................................................................15-9 General...........................................................................................................................15-9 Notification....................................................................................................................15-10

16 PLANNING GUIDELINES FOR NEW/UPGRADED POWER SYSTEMS..........................16-1 Introduction .........................................................................................................................16-2 Quick-Start Version .............................................................................................................16-2 Detailed Version..................................................................................................................16-4

Sources ..........................................................................................................................16-4 Voltage.......................................................................................................................16-4 Current Steady State ..............................................................................................16-5 Current Fault and Switching....................................................................................16-5

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Phasing......................................................................................................................16-5 Balance......................................................................................................................16-5 Transmission .............................................................................................................16-6 Distribution.................................................................................................................16-6

Paths ..............................................................................................................................16-6 Magnetic Induction.....................................................................................................16-6 Electric Induction .......................................................................................................16-7 Earth Conduction .......................................................................................................16-7

Receptors .......................................................................................................................16-7 Steady-State...................................................................................................................16-7 Fault................................................................................................................................16-7 Notification......................................................................................................................16-7

17 CONCLUSIONS .................................................................................................................17-1 Current State of Affairs........................................................................................................17-2 Short-Term Solutions ..........................................................................................................17-2 Long-Term Solutions...........................................................................................................17-3

Highway Grade Crossing Train Detection Equipment False Activation and Cab Signaling Equipment Operated at 60 Hz ........................................................................17-3 Damage to SPDs from Power System Fault Magnetic Induction ...................................17-4

Future Research .................................................................................................................17-5 Conclusion ..........................................................................................................................17-5

18 GLOSSARY........................................................................................................................18-1 Introduction .........................................................................................................................18-2 Glossary ..............................................................................................................................18-2

19 ERRATA SHEET ................................................................................................................19-1

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LIST OF FIGURES

Figure 2-1 The Source-Path-Receptor Interference Model........................................................2-5 Figure 2-2 Conductive Coupling Between Power and Railroad Systems ..................................2-7 Figure 2-3 Earth Conduction......................................................................................................2-7 Figure 2-4 Ground Potential Rise ..............................................................................................2-8 Figure 2-5 Wavelength Scaling when Measured in Wavelengths (), Printed Circuit

Boards and Joint Railroad Power Corridors Present the Same Geometry ........................2-9 Figure 2-6 Capacitive Coupling to an Object Close to an Overhead Line ...............................2-10 Figure 2-7 Thevenin Equivalent Circuit for Electric Field Coupling ..........................................2-11 Figure 2-8 Norton Equivalent Circuit for Electric Field Coupling..............................................2-11 Figure 2-9 Electric Field Induction ...........................................................................................2-11 Figure 2-10 Equivalent Circuit for Magnetic Field Coupling.....................................................2-12 Figure 2-11 Magnetic Field Induction.......................................................................................2-13 Figure 2-12 Shield Conductor for Magnetic Induction..............................................................2-14 Figure 2-13 Complete Circuit with Source, Path to the Load, Load, and Path from the

Load .................................................................................................................................2-16 Figure 2-14 Circuit with Differential Mode Signal .....................................................................2-17 Figure 2-15 Circuit with Common Mode Signal .......................................................................2-18 Figure 2-16 Circuit with Common Mode Interference and Differential Mode Signal ................2-19 Figure 2-17 Common Mode Voltage Converted to Differential Mode ......................................2-20 Figure 2-18 Circuit with Different Resistances to Ground........................................................2-21 Figure 2-19 Circuit with Unbalance: Common Mode Interference Converted into

Differential Mode Interference..........................................................................................2-21 Figure 2-20 Differential Mode and Common Mode Voltages on Railroad Signals...................2-22 Figure 2-21 European Interference Model ...............................................................................2-23 Figure 2-22 North American Interference Model......................................................................2-24 Figure 2-23 FCC Part 15 Radiated Emissions Limits for Digital Devices.................................2-30 Figure 3-1 Overview of the Electric Power System....................................................................3-5 Figure 3-2 Overhead Transmission Structure Types .................................................................3-9 Figure 3-3 Double Circuit Line with 2 Shield Wires 8 Total Conductors ...............................3-11 Figure 3-4 Distribution Transformer Feeding Single-Phase 120/240V Load from a Three-

Phase wye-Connected 12,470/7200V Primary with a Multi-Grounded Neutral...............3-14 Figure 3-5 Distribution Pole with Telephone and Cable Television Wires ...............................3-15

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Figure 3-6 4-Wire Multi-Grounded Feeders .............................................................................3-16 Figure 3-7 3-Wire Ungrounded Feeders ..................................................................................3-18 Figure 3-8 Single Wire Earth Return Primary ..........................................................................3-21 Figure 3-9 Positive Sequence Currents Sum to Zero in a Balanced 3-Phase System ............3-22 Figure 3-10 Zero Sequence Harmonic Current Returns in the Neutral Path ...........................3-23 Figure 3-11 Pad Mounted Transformers..................................................................................3-24 Figure 3-12 Pole Mounted Potheads for Overhead/Underground Transitions.........................3-25 Figure 4-1 Picture of Railroad Tracks ........................................................................................4-5 Figure 4-2 Typical AREMA Rail Section (133 lb. Rail) ...............................................................4-7 Figure 4-3 Thermite Weld in Rail ...............................................................................................4-7 Figure 4-4 Function