Latin America Collaborative Project on EPRI Latin American Collaborative

Chapter 1 - Introduction

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This report presents the results of efforts to develop an updated guide for helping power delivery organizations adapt and implement best practice asset management. Unlike other asset management guides available, the material presented here was specifically developed for application to the power delivery industry.

Background

Although proven and in wide use in the power generation sector, effective asset management processes have not been applied as widely in power delivery due to a host of challenges. These challenges include:

Chapter 1 - Introduction

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INTRODUCTION

This HVDC Overhead Line Design Guide is organized into two main parts. One part is devoted to system designs and one to component designs. Further, general information about HVDC is also included in the guide for the reader. HVDC systems are not as common as HVAC systems. Therefore, general information on the HVDC system such as its characteristics and the difference between HVDC and HVAC overhead lines will be helpful to the designers in understanding the requirements of HVDC overhead lines and in producing better designs.

Chapter 1 - Introduction

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Lightning flashes occur many times over the design life of a transmission line. The initiation of a flashover across line insulation may occur in response to a severe flash. This flashover process involves poorly defined gas-discharge physics, fast-changing electromagnetic fields relative to the structure. size, time-dependent nonlinear effects of corona development, and timeand currentdependent impedance of the earth electrodes. The problem must be evaluated in the context of large uncertainties in the lightning parameters and smaller, but significant, uncertainties in the line description.

Chapter 1 - Introduction

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INTRODUCTION

Chapter 1 - Introduction

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Background

Chapter 1 - Introduction

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Many electric utilities are considering or have already moved towards implementing formal asset management concepts and decision-making procedures based on minimizing equipment life-cycle costs and risks. A key step in this process is analyzing and understanding equipment historical performance and producing quantitative information on past and expected future fleet performance. The Electric Power Research Institute (EPRI) is developing analytical tools and methodologies required by this key step to provide a sound analytical basis to support asset management maintenance and replacement decision processes.

Chapter 1 - Introduction

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INTRODUCTION

Chapter 1 - Introduction

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Chapter 1 - Introduction

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INTRODUCTION

Chapter 1 - Introduction

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Power transformers can experience a wide variety of abnormal conditions that can affect their ability to function reliably. The root causes and the symptoms of these abnormalities can present in many forms. In addition, the readily available data useful for assessing transformer condition, notably, dissolved gas analysis (DGA), may only be gathered on a frequency of months to years. Consequently, accurately diagnosing a transformer’s condition is technically challenging.

Nonetheless, a transformer’s condition will degrade over its service life due to both normal insulation aging and the results of accumulated operational stresses. Therefore, it is an important asset management function for utilities to best understand the condition of these critical and expensive assets.

Chapter 1 - Introduction and Background

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Introduction

This report presents the initial results of an EPRI investigation into the attributes and capabilities of six commercially available high voltage SF6 circuit breaker online monitoring systems. Source material for this investigation was limited to the monitor suppliers’ publicly available technical literature and brochures. Consequently, the kind of information and level of details provided vary among the different monitors. Monitor testing was outside the scope of this work. Findings from this research can help utilities make more informed decisions about selecting, purchasing and implementing online monitoring systems to support enhanced circuit breaker maintenance and fleet management.

Chapter 1 - Introduction and Background

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Introduction

Online monitoring offers the potential to continuously evaluate the health of circuit breakers by identifying conditions that could lead to a failure. Early detection of incipient failure mechanisms can help utilities take corrective action before a failure occurs and help utilities diagnose breaker problems without taking the breaker offline. This traditional approach is costly and time consuming, and may result in a misdiagnosis. Moreover, online monitoring has the potential to provide insights on circuit breaker health and remaining service life that support fleet management decisions about future breaker repair and replacement.

Chapter 1 - Introduction and Background

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Introduction

Chapter 1 - Introduction and Background

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Introduction

Chapter 2 - High Voltage SF6 Circuit Breaker Monitor Assessment

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Researchers documented publicly available technical information provided by the suppliers of SF₆ high voltage circuit breaker monitoring systems at the time of report publication. Source material for this review was limited to published brochures and therefore subject to incomplete technical details and interpretations. EPRI does not endorse any particular monitoring system nor has EPRI substantiated any claims or technical abilities presented.

Literature on devices from the following manufacturers was reviewed:

Chapter 2 - High Voltage SF6 Circuit Breaker Monitor Assessment

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Literature on devices from the following manufacturers was reviewed:

Chapter 2 - Circuit Breakers

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Utilities have interest in maintenance and/or replacement decision support information derived from circuit breaker data analyses. The data required for such analyses should be predominantly information that most utilities already have available or that is obtainable with minimum additional effort. A balance must be made between all the information that could be useful to collect for analysis and the burden of collection. Furthermore, it should be recognized that not all utilities will be able to supply all requested information.

Chapter 2 - Guide Outline

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The design of an overhead line, be it an AC or DC, can be grouped into two main categories. One category is related to the overall performance of the system and the other related to the performance of individual components. The performance of the overall system must meet design criteria dictated either by external or internal standards. Each component must also meet a given set of design standards. The designs of the components are coordinated to produce an acceptable level of overall performance. For example, the structure must be designed to withstand the weather load encountered by the conductor that is also transferred to the footing of the structure. The foundation therefore must be strong enough to support the structure above it. Mechanically, all line components such as the structure, foundation, conductor, insulator and hardware must be designed with coordinated strengths to produce an acceptable line survival rate together. Further, the electrical performance aspect of line must also be addressed. The configuration of the structure must be selected to produce an acceptable level of flashovers from lightning, switching surges, power frequencies and to allow live-line maintenance.

Chapter 2 - Guide Outline

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Chapter 2 - Guide Outline

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Chapter 2 - Guide Outline

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Chapter 2 - The Lightning Flash and Its Parameters

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DEFINITIONS OF TERMS USED

The following terms have been defined to encourage consistent description of lightning phenomena among engineers and researchers.

backflashover. An electrical flashover of the line insulation caused by a lightning flash to the line grounding system (including supporting towers or shield wires).

flashover. An electrical discharge completed from an energized conductor to a grounded object or support. In some cases, it may clear itself without tripping a circuit breaker.

Chapter 2 - The Lightning Flash and Its Parameters

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DEFINITIONS OF TERMS USED

The following terms have been defined to encourage consistent description of lightning phenomena among engineers and researchers.

backflashover. An electrical flashover of the line insulation caused by a lightning flash to the line grounding system (including supporting towers or shield wires).

flashover. An electrical discharge completed from an energized conductor to a grounded object or support. In some cases, it may clear itself without tripping a circuit breaker.

Chapter 2 - MYCIN

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Diagnostic and decision making activities for power transformers are characterized by uncertainty and inexact reasoning. There are few precise rules or diagnostic criteria. Instead, subject matter experts use a variety of rules of thumb, augmented by experience and anecdotal evidence of problems specific to certain manufacturers, vintages or classes of transformers. This practice is more art than science. Any attempt to produce an algorithm to handle these tasks must be capable of reasoning under uncertainty. Often times, bits of non-specific evidence are accumulated from available sources to suggest a number of possible diagnostic hypotheses. Further testing is then selected to narrow the hypothesis to build enough confidence to make a reasonable decision for further action. The ideal power transformer assessment algorithm should replicate this process.

Chapter 2 - Power Delivery Asset Management Overview

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This chapter outlines the basics of power delivery asset management and describes the principles and fundamental processes of PDAM. For the foreseeable future, utilities will need to manage an array of potentially conflicting business objectives, including the need to maintain competitive economic performance, improve customer satisfaction, maintain high reliability, address regulatory uncertainty, and comply with increased environmental regulation. The result is that many utilities are considering or have moved towards implementing informal or formal asset management concepts and driving decision-making based on minimizing equipment life-cycle cost and risks and maximizing benefits. A structured asset management approach has been successful in many other industries and, when properly adapted to utility needs, can provide the framework, processes and tools to develop the most effective programs for building, operating and maintaining today’s power delivery infrastructure.

Chapter 2 - Power Delivery Asset Management Overview

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Chapter 2 - Site and Monitor Information

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The EPRI Transmission and Distribution Laboratory is located on 35 acres in Lenox, MA. It provides full scale indoor and outdoor high voltage testing, allowing the evaluation of new technologies as well as performing forensic studies and tests on existing assets.

The test monitor, a General Electric CB Watch 3, is six years old. Serial number 19 indicates this is an early unit. There may have been significant design and software improvements since this monitor was built.

Chapter 2 - Site and Monitor Information

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Chapter 3 - Examples of Output Calculations

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This section provides some examples of the output capabilities of modern on-line circuit breaker monitoring systems. These examples are for illustration purposes only. EPRI does not endorse any particular system nor has EPRI substantiated any claims or technical abilities presented.

Timing Calculations

Hitachi MSM-II

Timing parameters can be extracted from any breaker manufacturer or type using auxiliary switch timing.

Auxiliary switch timing can serve to calculate contact speed, reaction time and mechanism time.

Chapter 3 - Examples of Output Calculations

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Timing Calculations

Hitachi MSM-II

Timing parameters can be extracted from any breaker manufacturer or type using auxiliary switch timing.

Auxiliary switch timing can serve to calculate contact speed, reaction time and mechanism time.

Chapter 3 - HDVC Line Performance

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Introduction

The conventional wisdom concerning HVDC line design is that it is a simple extension of AC design. In a physical sense, HVDC lines are similar to AC transmission lines in that both use bare stranded conductors, and both must meet or exceed minimum specified electrical clearance to ground and to other conductors at operating voltage.

A direct comparison of performance between HVDC and AC should consider the level of maintenance required to maintain acceptable outage rates. HVDC lines are made of essentially the same materials as AC lines of a comparable voltage level. Normal weathering of components of foundations, structures, conductors, splices, clamps, insulators, and shield wires should be similar in a ±400 kV HVDC line and a 345-500 kV HVAC line.

Chapter 3 - HDVC Line Performance

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Introduction

Chapter 3 - HDVC Line Performance

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Introduction

Chapter 3 - HDVC Line Performance

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Introduction

Chapter 1 - Introduction to EMF Management

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1.1 Background

Concern about exposure to power-frequency (50/60 Hz) electric and magnetic fields (EMF) surfaced in the 1960s with the introduction of Extra High Voltage (EHV) transmission systems in the US [1] and the consequential high electric fields. These concerns were highlighted by a 1972 report of Russian workers becoming ill as they worked in high voltage substations [2]. Later in the decade the focus switched to magnetic fields with the publication of an epidemiological study correlating the distribution wiring near homes with childhood cancer [3]. This report triggered research efforts to address these concerns, which have now lasted over forty years. Today, many aspects of EMF exposure have been resolved, but the scientific issue concerning childhood leukemia in particular is not fully resolved, and there is continuing public concern. Research continues on outstanding issues, albeit in a reduced scope. EPRI retains one of the few remaining active EMF research programs.

Chapter 1 - Introduction to EMF Management

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1.1 Background

Chapter 3 - Lightning Performance of Transmission Lines

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OVERVIEW

Lightning flashovers are the most frequent cause of transmission lineoutages, resulting in a direct cost to utilities of more than $1 billionper year in damaged or destroyed equipment (EPRI 2001). There are alsosubstantial indirect costs involved due to the reduction in powerquality caused by frequent lightning outages. There are various methodsfor improving the lightning performance of lines, which may include:

Installing overhead ground (or shield) wires
Improving the tower footing resistance

Chapter 3 - Lightning Performance of Transmission Lines

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OVERVIEW

Installing overhead ground (or shield) wires
Improving the tower footing resistance

Chapter 3 - The Power Delivery Asset Management Model

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One key goal of EPRI’s asset management work is to develop a visual representation of the functional elements of a complete power delivery asset management implementation and their interrelationships as shown in Figure 1. Modeling the PDAM conceptual implementation illustrates the interfaces among the various components and shows the required inputs and expected outputs. The model helps to better define the important PDAM processes and to guide subsequent development work to identify data and analytical tool requirements for the individual elements and processes.

Chapter 3 - The Power Delivery Asset Management Model

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Chapter 3 - PTX Methodology

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The MYCIN rule-based inference engine outlined previously can be used to evaluate evidence in relation to any hypothesis. In the case of a decision support system for transformer diagnostics, the hypotheses that are to be evaluated are whether a given failure mode or failure mechanism is present. Evidence, in the form of test data and nameplate information, is evaluated by rules such as those described above to determine a “belief” that a given failure mechanism is present.

Chapter 3 - Test Plan with Data Added

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A test plan was created to measure with independent instruments the inputs to and outputs from the circuit breaker monitor as a method to assess the accuracy of the monitor.

The circuit breaker was not energized and had no connection to a load. Consequently, monitor functions such as wave capture and arcing times were eliminated from the Test Plan.

Breaker Monitor Inputs

Trip coil current
- Measure trip coil current during breaker opening event

Chapter 3 - Test Plan with Data Added

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A test plan was created to measure with independent instruments the inputs to and outputs from the circuit breaker monitor as a method to assess the accuracy of the monitor.

The circuit breaker was not energized and had no connection to a load. Consequently, monitor functions such as wave capture and arcing times were eliminated from the Test Plan.

Breaker Monitor Inputs

Trip coil current
- Measure trip coil current during breaker opening event

Chapter 3 - Wood Poles

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Wood poles are structures used extensively in the electric utility industry to support both transmission and distribution class overhead lines. Wood poles degrade gradually due to natural stressors, but can also fail due to sudden and catastrophic damage, such as from storms or wildfire. Many utilities perform routine/scheduled inspections on their wood pole fleets to mitigate safety risks due to loss of strength from degradation and often have these inspection and maintenance data readily available. Additionally utilities may also have historical wood pole replacement records. These readily available data may be useful in analyses to inform wood pole fleet inspection, maintenance and/or replacement decisions. See reference 3 for more details on EPRI’s wood pole analytical approaches and methodologies.

Chapter 2 - Basic EMF Principles

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2.1 EMF (Electric and Magnetic Fields)

2.1.1 Introduction - Electromagnetic vs Electric and Magnetic

Time varying electric and magnetic fields are coupled together and known as electromagnetic fields. If there is no time variation (i.e., the static case), the two fields uncouple and are treated independently. While slowly varying fields are still coupled, the coupling is subtle and it is possible to treat the electric and magnetic fields as if they were uncoupled and independent of each other [1]. In this case, the term “EMF” is used to describe the “for all practical purposes” independent quasi-static electric and magnetic fields. The source of the quasi-static electric field is electric charge which is (in turn) related to electric space potential and voltage. The source of the quasi-static magnetic field is electric current (moving charges).

Chapter 2 - Basic EMF Principles

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2.1 EMF (Electric and Magnetic Fields)

2.1.1 Introduction - Electromagnetic vs Electric and Magnetic

Chapter 4 - Comparison of Inputs and Outputs of Six Online Monitors

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Online Circuit Breaker Monitors: Comparison of Inputs

Table 4-1 compares the inputs to the six on-line monitoring systems reviewed. Blank spaces in the charts indicate the source literature did not provide that information.

Table 4-1:: Online circuit breaker monitors: comparison of inputs

Some items of note:

The inputs of most monitors are very similar.
Siemens literature is focused mainly on the business aspects of monitoring rather than technical specifications. The table may not represent all the inputs into its monitoring system.

Chapter 4 - Comparison of Inputs and Outputs of Six Online Monitors

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Online Circuit Breaker Monitors: Comparison of Inputs

Table 4-1 compares the inputs to the six on-line monitoring systems reviewed. Blank spaces in the charts indicate the source literature did not provide that information.

Table 4-1:: Online circuit breaker monitors: comparison of inputs

Some items of note:

The inputs of most monitors are very similar.
Siemens literature is focused mainly on the business aspects of monitoring rather than technical specifications. The table may not represent all the inputs into its monitoring system.

Chapter 4 - Conductors and Shield Wires

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Overhead transmission line asset managers desire to better understand the expected service lives of their overhead conductor and shield wire fleets (i.e. how long they will be fit for service) in order to support improved decisions about maintenance, repair and replacement. Such insights may be derived from analyses of historical condition assessments and/or replacement data, along with in-service fleet data. See reference 4 for more details on EPRI’s conductor and shield wire analytical approaches and methodologies.

Chapter 4 - HVDC Ground Electrodes

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HVDC lines can operate in bipolar or monopolar mode. When a DC line is operating in monopolar mode, a return path is required. The return path can either be a dedicated metallic return or an electrode. HVDC systems utilizing electrodes have been successfully designed and put into commercial operation. Some of the earlier HVDC systems utilizing electrodes have been operated for extended periods of time using the electrode return with no adverse effects. However, in recent years, concerns regarding the operation of electrodes have been raised.

Chapter 4 - HVDC Ground Electrodes

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Chapter 4 - HVDC Ground Electrodes

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Chapter 4 - HVDC Ground Electrodes

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Chapter 4 - Maintenance and Power Delivery Asset Management

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The previous chapters introduced the fundamental concepts of PDAM. This chapter will expand the explanation of the integration of maintenance within PDAM.

The Core Maintenance Concept

Based on the principles of PDAM, the overriding purpose of a maintenance process is to support the goals and objectives of the senior management or asset owner. Many maintenance programs are purely equipment-focused. That is, they are designed only around the requirements of the equipment without reference to the larger perspective of how the equipment’s performance can best support all of the organization’s objectives. This narrow focus often puts maintenance programs at a disadvantage when competing for limited resources.

Chapter 4 - Maintenance and Power Delivery Asset Management

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The previous chapters introduced the fundamental concepts of PDAM. This chapter will expand the explanation of the integration of maintenance within PDAM.

The Core Maintenance Concept

Chapter 4 - Technical Basis and Validation

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PTX provides a new and unique approach to assessing power transformer condition. It is natural to question how effective this approach is and how well does it compare with other methodologies. EPRI has undertaken quantitative studies to answer these questions. Because the two classes of PTX indexes, normal and abnormal, assess fundamentally different conditions, two different study methods were used.

Abnormal Condition Index

A different study approach was required to assess the effectiveness of PTX’s Abnormal Condition Indices (ACI). ACI is intended to identify transformers with unexpected conditions that, left unattended, may result in progression to a failure condition. This is the same objective as for more traditional DGA diagnostic methodologies. Consequently, while studying PTX’s effectiveness, it was appropriate to also study the effectiveness of other techniques.

Chapter 4 - Transmission Line Grounding: Theory

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INTRODUCTION

General

All electrical installations need a grounding system for safe and reliable operation. A grounding system is defined as the total set of steps taken to provide a low-impedance connection between the transmission line structures and the general mass of earth and to limit the buildup of potential gradients around it. Typically, a transmission line grounding system comprises the following components (see Figure 4-1):

A set of buried metallic conductors, called the grounding electrode.

Chapter 4 - Transmission Line Grounding: Theory

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INTRODUCTION

General

A set of buried metallic conductors, called the grounding electrode.

Chapter 4 - Example of Trip Time of Monitor vs. Timing Instrument

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Figure 4-1 is an example of CB Trip Timing Data: Instrument vs. Monitor. The Doble instrument is connected to the breaker main contacts; the CB Watch 3 data is from 52A contact. The difference between the instruments and the monitor is about 1 ms.

Figure 4-1: Average of three phases of trip time vs CB Watch 3 trip time.

Notes:

Y-axis scale very enlarged. Total variation of trip times between the Doble timing instrument and the CB Watch 3 monitor is less than 1 ms

Chapter 4 - Example of Trip Time of Monitor vs. Timing Instrument

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Figure 4-1: Average of three phases of trip time vs CB Watch 3 trip time.

Notes:

Y-axis scale very enlarged. Total variation of trip times between the Doble timing instrument and the CB Watch 3 monitor is less than 1 ms

Chapter 5 - Applying PTX for Asset Management

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Assessment of the condition and thereby the expected reliability of a transformer is a necessary task for a variety of activities. Fleet level decisions on maintenance budgets and capital investments need some measure of the condition or reliability of individual units in a fleet. Repair and replacement decisions at the unit level require an assessment of the condition to assess whether repair or replacement is necessary and, separately, whether repair or replacement is most appropriate economically. This section describes methods for condition assessment, whatever the purpose may be.

Chapter 5 - Comments on Online Circuit Breaker Monitoring Systems

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Because the source material for this investigation was limited to the monitor suppliers’ publicly available technical literature and brochures, the following comments represent the researchers’ interpretations. Testing or technical evaluation of monitoring systems was beyond the scope of this work. EPRI does not endorse any particular system nor has EPRI substantiated any claims or technical abilities presented.

Hitachi

The operating inputs and outputs of the Hitachi and some of the other monitoring systems are very similar. Hitachi claims to provide more information about interrupter internal condition.

Chapter 5 - Comments on Online Circuit Breaker Monitoring Systems

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Hitachi

The operating inputs and outputs of the Hitachi and some of the other monitoring systems are very similar. Hitachi claims to provide more information about interrupter internal condition.

Chapter 5 - Conductor Selection

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Introduction and Background

Overhead transmission lines are generally designed to last for a lifetime of 40 years. Many AC lines in service today in North America are 70 years old or more. This survival rate is a result of conservative utility design practices and very detailed product specifications. This reliability record has occurred is spite of a wide range of conductor types and sizes. Within the present transmission system there are far fewer HVDC lines but the ones that have been designed and built have been similarly successful in terms of mechanical and electrical reliability. The goal of this report is to describe the way pole conductors are selected for HVDC lines and to suggest possible subtle improvements.

Chapter 5 - Conductor Selection

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Introduction and Background

Chapter 5 - Conductor Selection

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Introduction and Background

Chapter 5 - Conductor Selection

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Introduction and Background

Chapter 5 - Density Calculation SF6 Using Instrument Data vs. CB Watch 3 Monitor

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The General Electric CB Watch 3 monitor outputs an SF₆ gas density, which is presumably based on the gas pressure and temperature. The following calculation checks the monitor output based on an independent calculation using the same directly measured values.

SF₆ does not act as an ideal gas under the pressures and temperatures used in this circuit breaker. Torlak et al.[^1] used the Redlich-Kwong equation, which yielded good results. This calculation will use the Soave modification that improves the temperature response.[^2] This equation of state requires the use of critical parameters of the SF₆ gas³, which are given here:

Chapter 5 - Density Calculation SF6 Using Instrument Data vs. CB Watch 3 Monitor

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Chapter 3 - EMF Measurements

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3.1 Techniques for Measuring Electric Fields

3.1.1 Types of Electric Field Meters

The most popular type of electric field meters are free-body type meters, which measure the field at a point in space, usually by measuring the current between two halves of a conductive, isolated body [1]. A less common type of free-body meter is the electro-optic field meter (which measure changes in the transmission of light through a fiber or crystal due to the influence of the electric field [2]). Alternatives to the free-body meter include ground reference type meters (which measure the current to ground of a probe [3]).

Chapter 3 - EMF Measurements

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3.1 Techniques for Measuring Electric Fields

3.1.1 Types of Electric Field Meters

Chapter 5 - Performance Measures

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In a PDAM approach, decisions to allocate resources are based on policy goals and objectives and the resources required to obtain those results. This includes both maintenance and replacement decisions.

Performance measures enable organizations to translate high-level policy objectives such as service reliability into quantifiable expressions of results to be achieved. They provide information by which asset managers can make tradeoffs across competing needs and measure the effectiveness of results. There are three broad classifications for PDAM performance metrics presented:

Chapter 5 - Performance Measures

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Chapter 5 - Transformer Spares Strategy Studies

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An effective spares management strategy is an essential component of risk-based fleet management programs that enable utilities to maintain reliability in a cost-effective manner. There are significant costs associated with spares inventories including capital, storage, and, for some equipment, maintenance and testing. These costs and the potential benefits from spares are a function of the number of individual spares kept at hand. Keeping too few spares may prolong outages while too many spares would increase capital and operating costs. However, there are no industry standards or guidelines to help utilities optimize the number or mix of spares. EPRI’s spares strategy evaluation methodology aims to fill this gap and to help utility users optimize their transformer spares practices through informed and risk-based decision making.

Chapter 5 - Transmission Line Grounding: Practical Guidelines

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INTRODUCTION

General Overview of Transmission Line Grounding

The purposes of transmission line grounding are to protect the line against the effects of lightning, to ensure the correct operation of the system protection control equipment, and to safeguard humans and animals that come into contact with transmission line structures. These purposes are achieved by providing a low-impedance connection between the transmission line structures and the general mass of earth and limiting the buildup of potential gradients around it. The components of a typical grounding system are shown in Figure 5-1. They consist of:

Chapter 5 - Transmission Line Grounding: Practical Guidelines

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INTRODUCTION

General Overview of Transmission Line Grounding

Chapter 6 - CB Watch 3 Alarms – Example SF6 Alarm Calibration

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Instrument measurements:

CB Watch Measurements

Gas Data

Gas pressure measured 86.57 psig

Gas temperature measured 32.4 °C

Gas density 43.31 g/l

Gas pressure at 20°C 81.66 psig

Gas liquefaction pressure at 20°C -

Short-term gas pressure leak rate 0.63 psi/h

Long-term gas pressure leak rate -

Long-term gas mass leak rate -

Long-term gas % leak rate -

Gas short-term extrapolated pressure at 20°C 81.86 psig

Gas long-term extrapolated pressure at 20°C -

Chapter 6 - CB Watch 3 Alarms – Example SF6 Alarm Calibration

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Instrument measurements:

CB Watch Measurements

Gas Data

Gas pressure measured 86.57 psig

Gas temperature measured 32.4 °C

Gas density 43.31 g/l

Gas pressure at 20°C 81.66 psig

Gas liquefaction pressure at 20°C -

Short-term gas pressure leak rate 0.63 psi/h

Long-term gas pressure leak rate -

Long-term gas mass leak rate -

Long-term gas % leak rate -

Gas short-term extrapolated pressure at 20°C 81.86 psig

Gas long-term extrapolated pressure at 20°C -

Chapter 6 - Conclusions

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This report enumerates and describes the types of data that have been found useful as inputs to EPRI fleet management analytics for circuit breakers, wood poles, conductors and shield wires, and transformer spares strategy studies. Useful parameters and related examples or descriptions were presented. These data may be useful in analyses to derive maintenance, replacement, and other asset management decision support information.

This report is intended to facilitate the data collection and sharing efforts and may also be used to inform stakeholders in less equipment or operations focused departments responsible for data storage at utilities. These analytical development efforts are on-going and the data identified as useful for these assets may change. More asset types are expected to be added in the future.

Chapter 4 - EMF Calculation Methods

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4.1 Introduction

This chapter describes practical methods for calculating electric and magnetic fields produced by the power system. Because of their importance, the calculation methods of overhead power line fields are treated in great detail. Often power line conductors are assumed straight, infinitely long, and parallel to each other and to a perfectly flat earth. These simplifications make possible the application of two-dimensional calculation methods for electric fields (Section 4.2) and magnetic fields (Section 4.3). Used with proper consideration for conditions of validity, two dimensional calculations can provide very useful results.

Chapter 4 - EMF Calculation Methods

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4.1 Introduction

Chapter 6 - Enterprise Integration

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Example Architecture

PTX is available in a format suitable for adaption in an enterprise asset management system. This section outlines one approach for installing PTX to query data from internal and external data sources, run the PTX analysis in an automated fashion, and publish the results to a database instance for use in further analysis and reporting. Actual implementation details depend on the utility data storage and transfer infrastructure. To implement PTX in the manner described herein, the user would need to identify or create the following:

Chapter 6 - HVDC Insulation

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Introduction

One of the key issues that impacts the insulation design of HVDC lines and substations is the contamination performance of the external insulation. The performance of external insulation is adversely affected when the insulating surfaces becomes contaminated with airborne deposits such as marine salt or industrial pollution. When wet, such deposits may form a conductive or partially conductive surface layer on the insulator, resulting in electrical discharge activity and in severe cases, flashover of the insulators.

Chapter 6 - HVDC Insulation

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Introduction

Chapter 6 - HVDC Insulation

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Chapter 6 - HVDC Insulation

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Introduction

Next Steps

Mon, 01 Jan 0001 00:00:00 +0000

The findings documented in this report represent the initial efforts of an ongoing research project. EPRI plans to add additional monitors and additional material based on member interest and support:

Member utilities are encouraged to suggest monitors for assessment
EPRI seeks to document utility use cases and experiences
Utilities are encouraged to contribute use cases, experiences and feedback
More utilities are piloting or applying online breaker monitors. The combined population of online monitors may help researchers to better understand their efficacy, e.g., detecting defects if utilities share their experiences. For those wishing to contribute data for case studies, it would be helpful to include:

Next Steps

Mon, 01 Jan 0001 00:00:00 +0000

Member utilities are encouraged to suggest monitors for assessment
EPRI seeks to document utility use cases and experiences
Utilities are encouraged to contribute use cases, experiences and feedback
More utilities are piloting or applying online breaker monitors. The combined population of online monitors may help researchers to better understand their efficacy, e.g., detecting defects if utilities share their experiences. For those wishing to contribute data for case studies, it would be helpful to include:

Chapter 6 - PDAM and Risk

Mon, 01 Jan 0001 00:00:00 +0000

Background

The term “risk” has appeared often in the preceding chapters. This chapter will provide an expanded discussion of risk and risk assessment and management.

In the broadest sense, risk can be considered as a measure of the uncertainty of business performance and as such is closely tied to the organization’s performance goals. The subject of risk has been extensively studied for financial assets and is generally considered to be the risk of not achieving the expected financial return. Risk has also been studied in detail for the power generation and energy trading side of the utility business. Here the desire is to assess energy portfolio exposures to commodity markets and customer loads, evaluate overall portfolio risk in terms of cash-flow-at-risk or value-at-risk, and assist in designing portfolio risk management programs. For power delivery, risk management is not so well formalized.

Chapter 6 - PDAM and Risk

Mon, 01 Jan 0001 00:00:00 +0000

Background

The term “risk” has appeared often in the preceding chapters. This chapter will provide an expanded discussion of risk and risk assessment and management.

Chapter 7 - CB Watch 3 Dashboard

Mon, 01 Jan 0001 00:00:00 +0000

Notes:

Alarms are shown in the software, but the specific parameters causing the 5 Overall CB Risk Index are not indicated.
Other problem indications on the dashboard are the “5” for control circuits and the “3” for the stored energy system.

There was a problem with the control circuit. A secondary circuit was used for tests.
The stored energy system seemed alright

In addition to the SF₆ alarms discussed in the previous slide, there were alarms for:

Cumulative rewind motor operation time > max

Chapter 7 - CB Watch 3 Dashboard

Mon, 01 Jan 0001 00:00:00 +0000

Notes:

Alarms are shown in the software, but the specific parameters causing the 5 Overall CB Risk Index are not indicated.
Other problem indications on the dashboard are the “5” for control circuits and the “3” for the stored energy system.

There was a problem with the control circuit. A secondary circuit was used for tests.
The stored energy system seemed alright

In addition to the SF₆ alarms discussed in the previous slide, there were alarms for:

Cumulative rewind motor operation time > max

Chapter 7 - Conclusions and Future Work

Mon, 01 Jan 0001 00:00:00 +0000

EPRI’s Power Transformer Expert System (PTX) software tool helps utilities better diagnose and assess the condition of power transformers utilizing a variety of inputs, including dissolved gas analysis. The tool has been widely and successfully applied at many utilities. Nonetheless, PTX development is an on-going multi-year effort and enhancements and changes to the algorithms and implementations will continue to be investigated. In the interim, there is a need for prospective users to better understand the theory and application of PTX and the work reported here is the initial result of efforts to meet that need. This report is not intended to help with installing and using the PTX software. There is a user’s guide accompanying the tool for that purpose.

Chapter 5 - Distribution Lines

Mon, 01 Jan 0001 00:00:00 +0000

5.1 Introduction

5.1.1 Contents

The first subject (covered later in this section) of the chapter is an introduction to distribution systems. Included are both an overview of distribution systems in the US and differences between these systems and those in Europe. Because the influence of connections to the earth are important in distribution systems, grounding (called “earthing” in Europe) is emphasized.

The next topic (Section 5.2) is a brief discussion on distribution line electric fields. Following this in the same section is a summary of the available information on distribution line magnetic field and magnetic field management options.

Chapter 5 - Distribution Lines

Mon, 01 Jan 0001 00:00:00 +0000

5.1 Introduction

5.1.1 Contents

Chapter 7 - HVDC Hardware Corona Testing

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Introduction

When specifying hardware for new HVDC lines or replacement hardware for existing HVDC lines utilities generally require that the hardware meet specific corona performance requirements.

While standards and test methods exist for testing hardware used on HVAC systems, no such material is available for HVDC systems.

HVAC tests are sometimes conducted on the hardware and the results obtained are then related to HVDC by utilizing the peak HVAC line to ground voltage as the equivalent HVDC voltage. This practice is not optimal as the phenomena of dc and ac corona are, physically quite different due to the effects of space charge and ion cloud formation.

Chapter 7 - HVDC Hardware Corona Testing

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

When specifying hardware for new HVDC lines or replacement hardware for existing HVDC lines utilities generally require that the hardware meet specific corona performance requirements.

While standards and test methods exist for testing hardware used on HVAC systems, no such material is available for HVDC systems.

Chapter 7 - HVDC Hardware Corona Testing

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

When specifying hardware for new HVDC lines or replacement hardware for existing HVDC lines utilities generally require that the hardware meet specific corona performance requirements.

While standards and test methods exist for testing hardware used on HVAC systems, no such material is available for HVDC systems.

Chapter 7 - HVDC Hardware Corona Testing

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

When specifying hardware for new HVDC lines or replacement hardware for existing HVDC lines utilities generally require that the hardware meet specific corona performance requirements.

While standards and test methods exist for testing hardware used on HVAC systems, no such material is available for HVDC systems.

Chapter 7 - Implementing Asset Management

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

There is no one optimum asset management implementation path. There are a wide variety of power delivery organizations, differing not only in size and type of service territory, but also in fundamental characteristics such as business unit responsibilities and ownership structure. Companies’ priorities and needs will vary. Therefore, to provide the most value to the widest audience, rather than an artificial “cookbook” formula, this chapter will present a broad implementation outline and the development of the key attributes necessary for good practice asset management – be it at the enterprise, business unit, or department level. The goal is to provide descriptive guidance and examples.

Chapter 7 - Implementing Asset Management

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

References

Mon, 01 Jan 0001 00:00:00 +0000

Applying Advanced Analytics to Improve Substation Asset Management and Maintenance: Circuit Breakers. EPRI, Palo Alto, CA: 2022. 3002024212.
Utilizing Industry-Wide Data to Better Understand Circuit Breaker Performance: Data Models, Definitions, and Application Examples. EPRI, Palo Alto, CA: 2023. 3002026874.
Overhead Transmission and Distribution Wood Pole Fleet Management. EPRI, Palo Alto, CA: 2023. 3002026884.
Overhead Transmission Conductor Fleet Management. EPRI, Palo Alto, CA: 2023. 3002026886.
Utilizing Industry-wide Data to Better Understand Power Transformer Performance: Data Models, Definitions and Application Examples. EPRI, Palo Alto, CA: 2023. 3002026873.

Chapter 8 - Utility Example -- Transmission Substation Asset Management - A BOTTOM-UP Approach

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

This chapter presents an example of how an electric utility in the Northeast United States developed an asset management program for transmission substations. The chapter focuses on the implementation and development of the organizational structure, people, and tools used in the program to achieve value from the organization’s assets.

Overview / History

The development of this program could be described as “bottom-up.” This is not to infer that the effort was without management support, but instead indicates that the program did not result from a top-level decision to develop asset management capabilities in a specific time using a formal roadmap. It did not start from a planned implementation of PDAM as described in preceding chapters. Instead, the development of this program was “organic,” in that it started with the formation of equipment peer teams and grew as the subject matter experts identified problems and developed solutions, and as the capabilities of the company matured. Nonetheless, the results adhere to and have many elements in common with PDAM concepts.

Chapter 8 - Utility Example -- Transmission Substation Asset Management - A BOTTOM-UP Approach

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Overview / History

Chapter 8 - HVDC Live Line Work

Mon, 01 Jan 0001 00:00:00 +0000

The focus of this chapter is on live work in overhead HVDC lines operating above 100 kV DC.
It does not address issues related to lines for electric transport that operate typically below 60 kV DC worldwide (in North America, electric transport systems operate at voltages typically below 1.2 kV DC [1]).

Also, this report is not a detailed treatise on live work, but addresses the main issues related to DC live work throughout . More detailed information on live work in general can be found in the references cited this report and summarized in the References section.

Chapter 8 - HVDC Live Line Work

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Chapter 8 - HVDC Live Line Work

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Chapter 8 - HVDC Live Line Work

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Chapter 8 - Monitor File Structure

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Seven to nine files are generated with each operation of the circuit breaker and periodically between operations.

Figure 8-1: Files generated with each circuit breaker operation

Each of the files has typically a cover page and six other pages. Only one of the seven pages has data.

The cover page does not indicate the contents of the file.

Figure 8-2: Cover page

Part of Typical Single Page with Data

Example of Monitor Presentation of Raw Data

Note Coil circuit DC voltage = 1.0 V. The monitor did not detect the alternate DC source used to operate the breaker

Chapter 8 - Monitor File Structure

Mon, 01 Jan 0001 00:00:00 +0000

Seven to nine files are generated with each operation of the circuit breaker and periodically between operations.

Figure 8-1: Files generated with each circuit breaker operation

Each of the files has typically a cover page and six other pages. Only one of the seven pages has data.

The cover page does not indicate the contents of the file.

Figure 8-2: Cover page

Part of Typical Single Page with Data

Example of Monitor Presentation of Raw Data

Note Coil circuit DC voltage = 1.0 V. The monitor did not detect the alternate DC source used to operate the breaker

Chapter 6 - EMF Management for Overhead Transmission Lines

Mon, 01 Jan 0001 00:00:00 +0000

6.1 Transmission Line Electric and Magnetic Field Characteristics

6.1.1 Introduction

Among the sources of EMF, power lines and in particular transmission lines (regarded as lines with voltages of 69 kV and above in the USA, or above 100 or 200 kV in Europe) have received the greatest attention. Prior to about 1982, the focus was on electric field, particularly from extra high voltage (EHV) transmission lines and substations. These installations produce the highest electric fields commonly encountered. Concerns about electric field [1-35] extended to such topics as short duration currents and spark discharges occurring when touching vehicles or other insulated objects under a transmission line. Long term exposure to electric fields was the subject of several studies [36-40]. Short term effects of voltages and currents induced by magnetic fields were also extensively studied [41-50].

Chapter 6 - EMF Management for Overhead Transmission Lines

Mon, 01 Jan 0001 00:00:00 +0000

6.1 Transmission Line Electric and Magnetic Field Characteristics

6.1.1 Introduction

Chapter 9 - Utility Example -- Transmission Substation Asset Management—A Top-Down Approach

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

This chapter presents an example of how an electric utility in the Midwest United States implemented a transmission line and substation asset management program over a six-year period. The study focuses on the implementation and development of the organizational structure, people, and tools used in the program to realize value from the organization’s assets. The focus of this chapter is on substations, even though transmission line assets were included in the program. Most of the principles presented here apply to other types of assets.

Chapter 9 - Utility Example -- Transmission Substation Asset Management—A Top-Down Approach

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Introduction

Chapter 9 - Conclusions and Next Steps

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Conclusions

Data from the monitor appears in reasonable agreement with instrument measurements
Algorithms providing information based on combinations of data are not revealed
The Dashboard is a good synopsis of breaker condition, but lacks ties to the data causing risk assessments, e.g., DC voltage too low. The source of data for this alert is unknown.
The risk assessment does not revert to “Good condition” after the problem is fixed
File structure of monitor data in this early version is difficult for users

Chapter 9 - Conclusions and Next Steps

Mon, 01 Jan 0001 00:00:00 +0000

Conclusions

Data from the monitor appears in reasonable agreement with instrument measurements
Algorithms providing information based on combinations of data are not revealed
The Dashboard is a good synopsis of breaker condition, but lacks ties to the data causing risk assessments, e.g., DC voltage too low. The source of data for this alert is unknown.
The risk assessment does not revert to “Good condition” after the problem is fixed
File structure of monitor data in this early version is difficult for users

Chapter 9 - HVDC Electrical Effects

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

The objective of this chapter is to provide an overview of electrical effects from HVDC lines to assist overhead transmission engineers in selecting the proper parameters for their designs. The chapter starts from explaining the physics of corona and, electric and magnetic fields, comparing the differences between AC and DC electrical effects to, presenting the state-of-the science on the topic. The chapter also highlights concerns to the transmission line designers. The chapter extracts materials from EPRI reports “Electrical Effects of HVDC Transmission Line – State of the Science” [1] and “500 kV Transmission Line Design: Overview of Design Parameter Interdependencies” [2], updates and provides additional information as required.

Chapter 9 - HVDC Electrical Effects

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Introduction

Chapter 9 - HVDC Electrical Effects

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Introduction

Chapter 9 - HVDC Electrical Effects

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Introduction

Chapter 7 - EMF Management of Transmission Cables

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7.1 Transmission Cables and the EMF Issue

7.1.1 Introduction

EMF is more commonly an issue that concerns overhead transmission lines. Objections to the presence of overhead power lines are sometimes caused by their visibility despite efforts by the electric utility industry to make them less obtrusive and more esthetically pleasing. Concerns about possible health effects due to EMF add to the desire on the part of some to eliminate overhead transmission lines altogether. This is why placing transmission lines underground is perceived as a solution to EMF concerns. However, while the electric field is eliminated, the magnetic field is not. Simply placing transmission lines underground, in itself, does not necessarily eliminate magnetic fields above the surface of the ground because the soil around underground cables has practically no effect on the magnetic fields. Soil, gravel, concrete, masonry, and fiberglass do not have high enough conductivity and/or relative permeability to significantly impact AC magnetic fields. Most new distribution lines are underground, but older existing lines are overhead and are subject to the same criticism. This chapter deals primarily with EMF from transmission cables, rather than EMF from distribution cables.

Chapter 7 - EMF Management of Transmission Cables

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7.1 Transmission Cables and the EMF Issue

7.1.1 Introduction

Chapter 10 - Conclusions and Recommendations for Additional Work

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Conclusions

With the successful development and acceptance of a number of EPRI analytical tools and equipment performance databases and the increased appreciation of asset management principles for guiding power delivery organizations, it was deemed appropriate to revisit EPRI’s Power Delivery Asset Management (PDAM) Guidelines. Working with utility advisors, the objective was identifying any additions required to make certain that the latest version fully addresses current utility needs. This report documents the results of the work to produce an updated guide, and includes two utility application examples, presenting detailed descriptions of two different approaches to developing transmission substation asset management programs and some lessons learned from their implementations.

Chapter 10 - Conclusions and Recommendations for Additional Work

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Conclusions

Chapter 1 - Introduction and Overview

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Introduction to the Circuit Breaker Refrence Guide (2023 Update)

The Need for a Comprehensive Reference on Power Circuit Breakers

High-voltage circuit breakers perform essential protection and control functions on power transmission networks. A breaker’s failure to operate as required can result in equipment damage, increased system disturbance and loss of load.

Utilities have been maintaining circuit breakers reliably for many years. However, the task has grown increasingly difficult due to several factors:

Chapter 1 - Introduction and Overview

Mon, 01 Jan 0001 00:00:00 +0000

Introduction to the Circuit Breaker Refrence Guide (2023 Update)

The Need for a Comprehensive Reference on Power Circuit Breakers

Utilities have been maintaining circuit breakers reliably for many years. However, the task has grown increasingly difficult due to several factors:

Chapter 10 - Lightning performance

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Lightning may cause outages of overhead lines in three different ways:

Shielding Failure: Lightning strikes may bypass the overhead shield wires to terminate directly onto the phase conductors. Given sufficient current this may result in a flashover of one or more insulators due to the voltage build-up on the phase conductors. The shielding failure rate is determined by considering the presence and position of the overhead shield wires with respect to the phase conductors. For a given arrangement, the shielding outage rate is equal to the number of strikes terminating on the phase conductor with a sufficiently high current to cause flashover.

Chapter 10 - Lightning performance

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Lightning may cause outages of overhead lines in three different ways:

Shielding Failure: Lightning strikes may bypass the overhead shield wires to terminate directly onto the phase conductors. Given sufficient current this may result in a flashover of one or more insulators due to the voltage build-up on the phase conductors. The shielding failure rate is determined by considering the presence and position of the overhead shield wires with respect to the phase conductors. For a given arrangement, the shielding outage rate is equal to the number of strikes terminating on the phase conductor with a sufficiently high current to cause flashover.

Chapter 10 - Lightning performance

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Lightning may cause outages of overhead lines in three different ways:

Shielding Failure: Lightning strikes may bypass the overhead shield wires to terminate directly onto the phase conductors. Given sufficient current this may result in a flashover of one or more insulators due to the voltage build-up on the phase conductors. The shielding failure rate is determined by considering the presence and position of the overhead shield wires with respect to the phase conductors. For a given arrangement, the shielding outage rate is equal to the number of strikes terminating on the phase conductor with a sufficiently high current to cause flashover.

Chapter 10 - Lightning performance

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Lightning may cause outages of overhead lines in three different ways:

Shielding Failure: Lightning strikes may bypass the overhead shield wires to terminate directly onto the phase conductors. Given sufficient current this may result in a flashover of one or more insulators due to the voltage build-up on the phase conductors. The shielding failure rate is determined by considering the presence and position of the overhead shield wires with respect to the phase conductors. For a given arrangement, the shielding outage rate is equal to the number of strikes terminating on the phase conductor with a sufficiently high current to cause flashover.

Chapter 8 - EMF Management for Substations

Mon, 01 Jan 0001 00:00:00 +0000

8.1 Introduction

Substations are key components for the operation and reliability of transmission and distribution systems. They serve as a point of connection and switching for transmission lines, sub-transmission feeders, generating circuits, and step-up and step-down transformers. Although very advanced, substations house important equipment requiring inspection and maintenance by utility personnel, who may be exposed to significant electric and magnetic fields.

Some decades ago, concerns about exposure to power frequency electric fields [1] were heightened by reports of complaints and health problems in high voltage (500 kV) Russian substations [2]. Exposure assessment [3-14] and epidemiological studies of electric utility workers [14-25] have confirmed that EMF exposure inside of a high voltage substation environment is one of the highest among occupational exposures.

Chapter 8 - EMF Management for Substations

Mon, 01 Jan 0001 00:00:00 +0000

8.1 Introduction

Chapter 11 - HVDC Line Maintenance Practices

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This chapter addresses technical considerations for maintenance strategies, practices and problems commonly related to HVDC and UHVDC lines operating above 100 kV DC.

Introduction

Traditionally, HVAC and HVDC overhead transmission lines have similar maintenance practices. HVDC lines are similar to HVAC lines in that both use bare stranded conductors and must meet or exceed minimum specified electrical clearance to ground and to other conductors under all operating conditions.

Since AC and DC lines operate in the same environmental conditions and have similar failure-modes, a skilled transmission line crew can patrol, inspect and repair both types of lines. Utilities typically take advantage of the installation similarities to share maintenance resources such as personnel, tools, equipment and vehicles, to provide a more cost-effective maintenance strategy.

Chapter 11 - HVDC Line Maintenance Practices

Mon, 01 Jan 0001 00:00:00 +0000

This chapter addresses technical considerations for maintenance strategies, practices and problems commonly related to HVDC and UHVDC lines operating above 100 kV DC.

Introduction

Chapter 11 - HVDC Line Maintenance Practices

Mon, 01 Jan 0001 00:00:00 +0000

This chapter addresses technical considerations for maintenance strategies, practices and problems commonly related to HVDC and UHVDC lines operating above 100 kV DC.

Introduction

Chapter 11 - HVDC Line Maintenance Practices

Mon, 01 Jan 0001 00:00:00 +0000

This chapter addresses technical considerations for maintenance strategies, practices and problems commonly related to HVDC and UHVDC lines operating above 100 kV DC.

Introduction

Chapter 9 - Shielding

Mon, 01 Jan 0001 00:00:00 +0000

9.1 Principles of Shielding for Power Frequency

9.1.1 Introduction

The IEEE dictionary defines (electromagnetic) shielding as “a housing, screen, or other object, usually conducting, that substantially reduces the effect of electric or magnetic fields on one side thereof, upon circuits or devices on the other side” [1]. In this chapter, which is specific to power frequencies, the term shielding more generally refers to the use of enclosures, flat plates, screens, meshes, or conducting loops to reduce electric or magnetic field magnitudes throughout some volume of space.

Chapter 9 - Shielding

Mon, 01 Jan 0001 00:00:00 +0000

9.1 Principles of Shielding for Power Frequency

9.1.1 Introduction

Chapter 12 - HVDC Voltage Detector Evaluation

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Historically HVDC schemes have been expensive due to the cost of the terminal equipment. Today, with continuing development of power electronics the terminal equipment is becoming both less expensive and more reliable. In the past few years, HVDC transmission is seeing a resurgence for its traditional long-distance applications and is also being implemented for shorter lines operating at lower voltages. Due to its historically limited applications, international standards which are clearly defined for HVAC transmission systems are often absent for HVDC. One example of this is standards for HVDC voltage detectors. IEC 61243-1:2021 [1] covers voltage detectors for use on HVAC lines rated from 1 kV to 800 kV AC, but even though there are several commercially available voltage detectors for use on HVDC lines, requirements for their use, performance and operation are not covered in any international standards.

Chapter 12 - HVDC Voltage Detector Evaluation

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Introduction

Chapter 12 - HVDC Voltage Detector Evaluation

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

Chapter 12 - HVDC Voltage Detector Evaluation

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Introduction

Chapter 10 - Residential of EMF Management

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10.1 Introduction

Because power frequency electric and magnetic fields are ubiquitous and because people spend a large portion of their time in the home, over the course of the EMF issue there has been considerable interest in assessing residential field levels. There is also an interest to identify the sources of fields and find ways to reduce residential field exposure. Electric fields in the home are relatively small and inconsequential. Therefore, most of this chapter is dedicated to magnetic fields.

Chapter 10 - Residential of EMF Management

Mon, 01 Jan 0001 00:00:00 +0000

10.1 Introduction

Chapter 13 - AC to DC line conversion

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Enhancing the capability of existing ac transmission assets is of paramount concern to producers, distributors, and consumers of electrical energy. A wide field of technical options has been developed for that purpose, including both system- and transmission-related options. The options include compensation, Flexible AC Transmission System (FACTS) technology, phase-shifting methods, Wide Area Management System (WAMS) approaches, and new control technologies. The latter includes a wide variety of options to enable ac circuits to accommodate greater flows, including those based on more accurate and specific assessment of real-time conditions.

Chapter 13 - AC to DC line conversion

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Chapter 13 - AC to DC line conversion

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Chapter 13 - AC to DC line conversion

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Chapter 11 - School, Commercial, and Industrial EMF Management

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11.1 Environmental Field Surveys

11.1.1 Review of Past Surveys

Electric and magnetic fields are produced not only by the generation and transmission of electric energy, but also by its distribution and use. Electric fields are generally small outdoors away from power lines and indoors in residences, schools, and commercial environments, and in most industrial environments. However, magnetic fields found in schools, commercial, industrial, and other environments may contribute significantly to a person’s overall exposure to magnetic fields.

Chapter 11 - School, Commercial, and Industrial EMF Management

Mon, 01 Jan 0001 00:00:00 +0000

11.1 Environmental Field Surveys

11.1.1 Review of Past Surveys

Chapter 12 - EMF Compatibility

Mon, 01 Jan 0001 00:00:00 +0000

12.1 Introduction

Modern technology continues to introduce a variety of new devices into our everyday life and the workplace. With this proliferation of new devices comes the increased possibility that some of these devices may be susceptible to external electric and/or magnetic field influence. In some cases, however, newer equipment may replace older, more susceptible systems with more robust, hardened systems which are less sensitive to external field influence.

In this chapter, we look at several types of equipment and systems which either may be prone to ac (and also dc) magnetic field interference or have been in the past:

Chapter 12 - EMF Compatibility

Mon, 01 Jan 0001 00:00:00 +0000

12.1 Introduction

In this chapter, we look at several types of equipment and systems which either may be prone to ac (and also dc) magnetic field interference or have been in the past:

Laboratory Flashover Performance for DC

Mon, 01 Jan 0001 00:00:00 +0000

Table 1: Summary of the collected contamination flashover laboratory results for various DC insulator types

Salt-Fog

Disc

Salinity [g/l]

U_??

N/A

−

0.33

33 Pigini

Clean Fog

Disc

SDD [mg/cm²]

U_??

Laboratory Flashover Performance for DC

Mon, 01 Jan 0001 00:00:00 +0000

Table 1: Summary of the collected contamination flashover laboratory results for various DC insulator types

Salt-Fog

Disc

Salinity [g/l]

U_??

N/A

−

0.33

33 Pigini

Clean Fog

Disc

SDD [mg/cm²]

U_??

Laboratory Flashover Performance for DC

Mon, 01 Jan 0001 00:00:00 +0000

Table 1: Summary of the collected contamination flashover laboratory results for various DC insulator types

Salt-Fog

Disc

Salinity [g/l]

U_??

N/A

−

0.33

33 Pigini

Clean Fog

Disc

SDD [mg/cm²]

U_??

Laboratory Flashover Performance for DC

Mon, 01 Jan 0001 00:00:00 +0000

Table 1: Summary of the collected contamination flashover laboratory results for various DC insulator types

Salt-Fog

Disc

Salinity [g/l]

U_??

N/A

−

0.33

33 Pigini

Clean Fog

Disc

SDD [mg/cm²]

U_??

Questionnaire on HVDC Line Performance

Mon, 01 Jan 0001 00:00:00 +0000

Questionnaire with Cover Letter

CIGRE Working Group B2.41 is presently studying the conversion of HVAC lines to HVDC. Preferential Subject 2 at the most recent Study Committee B2 technical session concerned the same subject. Subsequent discussions in B2 raised the broader possibility that it may be useful for CIGRE B2 to develop a broad technical guide to HVDC line design. In response to these activities and discussions, this preliminary questionnaire was prepared.

Questionnaire on HVDC Line Performance

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Questionnaire with Cover Letter

Questionnaire on HVDC Line Performance

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Questionnaire with Cover Letter

Questionnaire on HVDC Line Performance

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Questionnaire with Cover Letter

Chapter 2 - Circuit Breaker Fundamentals

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Introduction

This chapter presents a basic introduction to power circuit breakers, including:

Interruption theory
- Operating Mechanisms
- Insulating Media
- Trouble and Failure Modes
- Life-Limiting Factors
- Specifics of Circuit Breaker Interruption
Oil circuit breakers
Air-blast circuit breakers
Air and SF₆ compressors and their associated air and gas systems

Interruption Theory

A power circuit breaker is a device for making, maintaining, and breaking (interrupting) an electrical circuit between separable contacts under both load and fault conditions.

Chapter 2 - Circuit Breaker Fundamentals

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

This chapter presents a basic introduction to power circuit breakers, including:

Interruption theory
- Operating Mechanisms
- Insulating Media
- Trouble and Failure Modes
- Life-Limiting Factors
- Specifics of Circuit Breaker Interruption
Oil circuit breakers
Air-blast circuit breakers
Air and SF₆ compressors and their associated air and gas systems

Interruption Theory

A power circuit breaker is a device for making, maintaining, and breaking (interrupting) an electrical circuit between separable contacts under both load and fault conditions.

Chapter 3 - Circuit Breaker Diagnostic testing

Mon, 01 Jan 0001 00:00:00 +0000

Introduction

This draft chapter describes and explains a series of diagnostic tests for circuit breakers. Diagnostic testing was selected as the first chapter to be written on the basis of input from EPRI members who identified a pressing need for better information and guidance on the efficacy of different diagnostic tests.

Tests Inlcuded

To develop the foundation for this chapter, in 2014 descriptions of six established diagnostic tests were adapted from Effectiveness Assessment of Circuit Breaker Diagnostics: Characterization of Established Diagnostic Tests and Simulator Development. EPRI, Palo Alto, CA: 2014. 3002004007.

Chapter 3 - Circuit Breaker Diagnostic testing

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Introduction

Tests Inlcuded

Chapter 4 - Investigating and Understanding Circuit Breaker Problems and Failures

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Introduction and Overview

This chapter is directed to utility engineering staff involved in maintenance of high voltage circuit breakers. The objective is to provide information and guidance to support effective practices that maintain service reliability and extend breaker life. The work complements other EPRI efforts associated with circuit breaker knowledge capture, training, field guide development, and maintenance.

One important aspect of an effective circuit breaker maintenance program is the identification of failures and problems that can occur during a circuit breaker’s lifetime. These failures and problems vary for each circuit breaker depending on such factors as type of interrupting medium (oil, vacuum or SF₆ gas), type of operating mechanism (pneumatic, hydraulic or spring), type of bushings (oil-filled capacitor, SF₆ gas filled or solid), differences in manufacturer’s designs, operating and environmental conditions as well as the circuit breaker’s maintenance program. Improvements in the effectiveness of the circuit breaker’s maintenance program can be made by identifying failures and problems that can occur to that circuit breaker and to develop a maintenance program that will detect and prevent or minimize damage from these events occurring.

Chapter 4 - Investigating and Understanding Circuit Breaker Problems and Failures

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Introduction and Overview

Chapter 5 - Circuit Breaker Lubrication

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Introduction

This chapter is directed to utility engineering staff involved in maintenance of high voltage circuit breakers. The objective is to provide information and guidance to support effective lubrication practices that maintain service reliability and extend breaker life. The work complements other EPRI efforts associated with circuit breaker knowledge capture, training, field guide development, and maintenance.

High voltage circuit breakers require very fast operation of complex mechanical assemblies for successful operation. Consequently, various critical components of these mechanisms, such as bearings, must be properly lubricated to assure correct motion. Aged or improperly specified or applied greases can slow mechanism operation beyond acceptable limits. Therefore, the choice of lubricants can affect the reliable operation of a breaker. However, lubricant formulations have improved in the last decade and many of the greases originally specified by breaker manufacturers may no longer be the best choice, may have been reformulated or may not be available. There is little guidance for utilities to help understand the issues involved in selecting the proper lubricant for maintaining breakers for specific applications.

Chapter 5 - Circuit Breaker Lubrication

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Introduction

This chapter is directed to utility engineering staff involved in maintenance of high voltage circuit breakers. The objective is to provide information and guidance to support effective lubrication practices that maintain service reliability and extend breaker life. The work complements other EPRI efforts associated with circuit breaker knowledge capture, training, field guide development, and maintenance.

Chapter 6 - Pump and Compressor Maintenance

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Introduction

This chapter presents interim results of work conducted as part of EPRI’s high voltage circuit breaker life management program and documents the initial results of investigations of issues concerning transmission class circuit breaker pump and compressor maintenance and possible improvements in materials and practices that could improve maintenance effectiveness.

Historically, high voltage circuit breaker maintenance has been based on service time and, to a lesser extent, operations count. Such an approach has served the industry well but recent concerns, such as aging infrastructure, limited maintenance resources, and increased demand for service reliability, have prompted maintenance and asset managers to investigate possible maintenance improvements. Understanding the aging of high voltage circuit breaker subsystems and components is a necessary step in fashioning better maintenance programs.

Chapter 6 - Pump and Compressor Maintenance

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Introduction

Chapter 7 - Evaluation of Cleaners for SF6 Circuit Breaker Interrupters

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Introduction

Overview

The main function of a power circuit breaker is to interrupt current upon receiving a signal to open and to connect current carrying equipment together when commanded to close. High voltage circuit breakers perform a critical role in the operation of the electric power delivery system. Not only are they integral for the protection of other system components under fault conditions but their reliable switching operations also are necessary for maintaining optimum system conditions and power transfers during normal operating and maintenance situations. A breaker’s failure to operate as required may result in equipment damage, increased system disturbance, increased energy costs and/or loss of load.

Chapter 7 - Evaluation of Cleaners for SF6 Circuit Breaker Interrupters

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Introduction

Overview

Chapter 8 - Transmission Circuit Breaker Specifications and Procurement

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Introduction

This chapter discusses specifications and procurement of high voltage power circuit breakers rated 72.5kV and above and is directed at currently available breakers. Some content may not apply to older breakers.

When requesting circuit breakers for lower voltages, such as 23, 34.5 & 46kV, the 72.5kV model is typically offered with some possible modifications for the reduced clearances. For example, bushings rated for the lower system voltage.

At present, the vast majority of high voltage circuit breakers available in this voltage range utilize Sulfur Hexafluoride (SF₆) gas in a single pressure system for current interruption and dielectric insulation. Alternatives include vacuum interrupting and utilizing dry air for interruption and/or insulation.

Chapter 8 - Transmission Circuit Breaker Specifications and Procurement

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Introduction

Chapter 9 - Installation

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Introduction

As a continuation of the material in Chapter 8, Specifications and Procurement, this chapter will also be limited to single pressure SF₆ transmission circuit breakers rated 72.5kV and above. The circuit breaker installation is assumed to be in an outdoor substation. Circuit breakers installed in indoor substations require methods, practices and procedures outside the scope of this discussion.

Because of the wide variation of type and models provided by the manufactures, this chapter is not meant to provide comprehensive or detailed instructions. Instead, consider this an overview providing guidance from delivery to placing a circuit breaker into service. As always, manufacturers’ guidance and applicable standards should be followed. Best safety, operation and construction practices must be followed throughout the installation, test and commissioning of the circuit breaker.

Chapter 9 - Installation

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Introduction

Chapter 10 - Continuing Development

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EPRI’s Circuit Breaker Guidebook is being developed to capture the knowledge of leading breaker experts to provide a comprehensive reference on breaker procurement, operation, maintenance, and life-cycle management.

Development of the Guidebook is an ongoing multiyear effort. Diagnostic testing was selected as the first chapter to be written on the basis of input from EPRI members who identified a pressing need for better information and guidance on the efficacy of different diagnostic tests. Investigating and understanding problems and failures was selected as the second chapter based upon input from EPRI members who expressed a high level of interest in learning more about how and why circuit breakers fail and how to perform a root cause analysis of the failure. Additional chapters are being added based on utility guidance.

Chapter 10 - Continuing Development

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