The October/November Issue of the Electrical Insulation Magazine has been released. Use the accordion headings below to explore this issue’s content, and visit the IEEE Xplore for full magazine access.
Assessment of In-Service Transformers Filled with Synthetic Ester at 33 kV and Below
Muhammad Daghrah; Oguz Onay
Conductivity and Dielectric Dissipation Factor (tan δ) Measurements of Insulating Oils of New and Aged Power Transformers—Comparison of Results Between Portable Square Wave and Conventional Bridge Methods
Welson Bassi; Hédio Tatizawa
Thermal Ratings of Electrical Insulation Materials—How Are They Determined and Used?
Edward Van Vooren
I picked up my first copy of IEEE Electrical Insulation Magazine around 25 years ago, and it was like finding the picture for the jigsaw puzzle I was putting together. More than that, I saw there was a role for me in oil research that I could spend many years working on. At the time I was a new chemistry post-graduate starting work in the electricity supply industry and struggling with a project on transformer oil. I had been attracted to the project because I had worked in the field of oil research previously, having spent time formulating new engine oil products using, among other things, synthetic base oils and esters. However, I quickly found that the electricity supply industry was quite different from working in lubricants and that when it comes to oil, things change more slowly. I found it difficult to understand why synthetics were not already being embraced when they offered advantages over mineral oils.
One day in the university library, I came across a copy of IEEE Electrical Insulation Magazine from early in 1995. A paper in there did not really help me to understand why synthetic oils were not very popular, but it definitely helped me to understand a lot more about the industry I had just joined—about how long things tended to stay generally the same and how little was actually understood about the chemistry of insulating oils. “Electrical Insulating Oils Part I: Characterization and Pre-treatment of New Transformer Oils”  could have been written for me; it gave me historical context and an understanding of the market and explained that while we can estimate how many molecules might be present in the oil, most of them are unidentified because it made no economic sense to identify them all. It also gave me the second paragraph of my thesis, its first citation, and so many useful references. Looking back at the article now, I find it amazing that so many names that meant nothing to me then are people I have met and have had the pleasure of working with.
I quickly learned that the working environments for lubricants and insulating oils are very different and that moving to something unknown should only be done with caution and much study. Many of the topics that have been investigated on both synthetic and natural esters were not previously understood or were overlooked about mineral oil and much has been published on all three fluid types in the intervening years. Particularly important has been the work undertaken by research groups investigating dielectric strength in non-uniform electric fields and impulse strength over larger gap distances; here we see differences in the fluids that must be taken account of in designing transformers. It hardly seems fair to suppliers of more recently developed fluids, I hesitate to say “new” for products that have been around almost as long as I have, that such rigour has to be applied when wanting to switch from mineral oil to an ester, but we have less tolerance for failures now, there is greater dependency on reliable electricity, and changing a material when we do not know everything about it can seem risky.
Nevertheless, we can see esters starting to come into use in transformers at transmission voltages now. TransnetBW was first to energise natural-ester filled transformers at 420 kV using a soy based natural ester. The November/ December 2020 edition of this Magazine featured a National Grid transformer in the test bay at Siemens—it was the first 400-kV synthetic-ester filled transformer in the world and is one of three now in service in North London. In the week as I write, I have seen a video online of another ester-filled transformer being transported through Northumbria to another National Grid site. Taking the step to transmission voltages was based on research efforts from around the world and gaining the confidence that a transformer design could be made at that voltage to work with esters. National Grid contributed to this global research effort, largely through the research group at University of Manchester, but they also worked with GE at Stafford.
Buying an ester-filled transformer is only one part of the story. It then has to be incorporated into a network’s fleet of transformers. We need to understand how to manage it through its whole lifecycle. Researchers have looked at ester performance in small laboratory samples for many years, trying to reflect the conditions in a transmission transformer containing many orders of magnitude more oil. These studies aim to support asset managers in understanding how to manage the fluid over time, but given the importance of oil testing in assessing transformer condition, the more important aspect of this work is to ensure that we retain our diagnostic capabilities. With time and experience these laboratory studies will be supported and validated by in-service experience.
The contribution in this issue from Daghrah and Onay looks to do exactly that by examining in-service ester-filled units to understand more about the performance of the fluid based on findings over the last 20 years. This is a welcome contribution, but engineers and chemists working together in CIGRE, IEC, and IEEE are going to need more data, from more transformers and from more utilities, to improve the tools that asset managers rely on—maintenance and diagnostic guides built on operational information.
With transformers filled with esters in a fleet, there are other practical challenges to be dealt with by an asset manager. Where the K-Class property of fluids is an important characteristic that may have driven the choice of ester, it needs to be maintained. Research suggests that as they age normally, esters will retain their high fire point. But, it is incumbent upon the asset owner to ensure that this is not compromised by contamination with mineral oils. Procedures need to be in place to ensure that mineral oils and esters do not mix. The Siemens unit referred to earlier was painted blue to make a clear statement that it is different from other transformers to any observer, but the absence of mineral oil from the site will also prevent top-up accidents. Where both mineral oil–filled and ester-filled transformers are found on the same site, there are clear markings. But having both on one site also leads to another challenge—oil–water separators designed for mineral oil may not separate esters as easily. Users are already looking into the requirements for ensuring prevention of pollution from both fluids at the same time.
This Magazine, among other publications, has included papers ,  suggesting we can perhaps expect longer lives for the active parts of transformers containing esters. However, ester-filled transformers will, like all assets, age, and there will be a need to understand more about end of life. Are there options for life extension? Will there be special considerations for disposal? Can we re-use the fluids for other assets?
With transformer lives running into decades, the opportunity for new fluids to have an impact may be small. But who knows where the next challenge or opportunity may come from? By the time today’s transformers are reaching the end of their lives at the end of the century, do we imagine that we will still be relying on mineral oil for new assets? It seems more likely that we will have to move to a more sustainable alternative—utilities and manufacturers alike should be looking for innovations that could disrupt the way we currently do things. It seems likely that natural esters in particular will play a big part in that, but other bio-based fluids are already starting to appear. We may have to learn more quickly than we have in the past how to accommodate new fluids into our networks.
The younger version of me may have been frustrated in my naïveté at the slow pace of change in the movement away from mineral oils toward synthetic fluids. But, there are definitely exciting times ahead as we move to more sustainable and environmentally sound solutions in future.
I am still waiting on Electrical Insulating Oils Part II.
 A. Sierota and J. Rungis, “Electrical insulating oils. I. Characterization and pre-treatment of new transformer oils,” IEEE Electr. Insul. Mag., vol. 11, no. 1, pp. 8–20, Jan.-Feb. 1995.
 M. A. G. Martins, “Vegetable oils, an alternative to mineral oil for power transformers—Experimental study of paper aging in vegetable oil versus mineral oil,” in IEEE Electr. Insul. Mag., vol. 26, no. 6, pp. 7–13, Nov.-Dec. 2010.
 G. K. Frimpong, T. V. Oommen, and R. Asano, “A survey of aging characteristics of cellulose insulation in natural ester and mineral oil,” in IEEE Electr. Insul. Mag., vol. 27, no. 5, pp. 36–48, Sep.-Oct. 2011.
From The Editor
It is at least as important to think about where we should go as describing where we are now. The world is faced with numerous challenges, some of which were put on hold while we were (are) dealing with COVID-19. A number of these challenges involve us, working in the field of electrical insulation. Think about the accelerated developments in electrical transport, “green” energy, HVDC, and such. The IEEE Electrical Insulation Magazine wants to be a platform for ideas and roadmaps that provide ways to tackle these challenges. So, we welcome articles that present such ideas and roadmaps.
This issue of the Magazine starts with two articles on quality assessment of oils and esters used in transformers, key components of the grid. The third article is about how to determine and use the thermal ratings assigned to electrical insulating materials.
The first article in this issue, “Assessment of in-service transformers filled with synthetic ester at 33 kV and below,” is authored by Muhammad Daghrah and Oguz Onay, of M&I Materials Ltd., United Kingdom. The authors provide an introduction in terms of key benefits and in-service practices for condition assessment of transformers filled with synthetic esters in contrast with mineral oil. The results of a survey of 12 transformers filled with synthetic ester (11 kV/415 V and 33 kV/11 kV) are presented and discussed, including liquid quality and dissolved gas analysis (DGA) measurements. The transformers were chosen among the most loaded units from the transformer fleet, with an average loading from 0.5 to 0.8 p.u. All assessed transformers did not undergo any oil reconditioning or reclamation processes. Ester samples were characterized based on chemical parameters (color, neutralization value, and water content), electrical parameters (breakdown voltage, DC resistivity, and dielectric dissipation factor), fire point, and DGA tests. The authors conclude that end users can follow the same maintenance protocols with synthetic esters as they do with mineral oils, given that they use the relevant standards and in-service limits for synthetic esters such as the IEC 61203 and IEEE C57.155. DGA evaluation methods and key gases used to identify faults in mineral oil–filled transformers can also be applied for synthetic ester–filled transformers.
The second article, authored by Welson Bassi and Hédio Tatizawa, Institute of Energy and Environment of the University of São Paolo, Brazil, is titled “Conductivity and dielectric dissipation factor (tan δ) measurements of insulating oils of new and aged power transformers—Comparison of results between portable square wave and conventional bridge methods.” In this article, the authors compare values of tan delta calculated using conductivity measurements and tan delta bridge measurements. First, they make a direct comparison between the two methods for temperatures ranging from 25 to 100°C by using a simple expression relating the conductivity and tan delta. In a next step, they estimate the conductivity and tan delta at higher temperatures based on the value at ambient temperature (25°C) by assuming a certain activation energy for the conduction process. The authors show that the square wave method consistently provides tan delta values lower than those obtained by the bridge method, especially at lower temperatures. The authors argue that especially the values at 90 and 100°C are of importance, and in this temperature range the square wave method used on oil of poor condition provides tan delta values up to 25% lower than the bridge method. The authors claim that the main advantages of using the square wave method are lower costs, portability, and mobility, enabling field measurement immediately after oil sampling and preservation of the sample without risk of loss of properties or contamination.
The third article is titled “Thermal ratings of electrical insulation materials— How are they determined and used?” authored by Edward Van Vooren of ELTEK International Laboratories, USA. The focus of this article is on thermal ratings assigned to electrical insulating materials (EIM) and is intended to link with an article by Paul Gaberson on thermal rating for insulating systems, published in the May/June issue of the Magazine. After revisiting the different stress factors any electrical insulation system (EIS) can expect during operation, and how testing stages with the different stress factors should be arranged, the author focuses on EIM thermal rating. Thermal index ratings and relative thermal index ratings are discussed and compared. Then, the discussion moves to how to determine the thermal rating. Evaluations based on “end of test” and “end of performance” are discussed and examples are given for a range of insulating materials. The article ends with a discussion on how to make best use of the concept of EIM thermal rating in the design of electrical insulation equipment.
News from Japan
John J. Shea
Condition Monitoring with Vibration Signals
H. Ahmed and A.K. Nandi
John Wiley & Sons Ltd.
111 River Street
Hoboken, NJ 07030 http://www.wiley.com
433 pp., $135 (Hardcover), 2020
Condition monitoring of rotating machines using vibration analysis has become a key technique for predicting failures in rotating machines. Machine condition monitoring is the process of monitoring rotating machine health and is especially useful for sensitive and critical applications where there could be a high cost for unplanned downtime (e.g., wind turbines, oil and gas, aerospace, military, marine, and automotive). This book provides the most up-to-date information on vibration monitoring techniques for rotating machinery.
The majority of the book covers techniques for detecting and classifying faults in rotating machines, including feature-extraction, feature-selection, and feature-classification methods; machine learning; and data compression sampling. Many examples and case studies of vibration data are given to show the application of the methods described.
For those new to this technology, this book provides a good way to quickly learn about vibration monitoring in rotating machines. The book begins by introducing the basic principles of rotating machine vibration and acquisition methods along with the various types of vibration signals that can be encountered and the most current data acquisition techniques used to acquire vibration data. This background provides the reader with a good introduction and the necessary fundamentals to appreciate the book. The remainder of the book delves into the details of vibration monitoring. Some of the major topics cover several signal processing techniques in both time and frequency domains, machine learning algorithms, fault detection, data compression methods to reduce data with minimal information loss, and neural network methods to classify and identify fault precursors.
With an emphasis on signal processing methods and mathematics behind each of the techniques presented and less of an emphasis on the practical implementation of attaching vibration sensors to machines and the associated systems necessary to power and communicate with these sensors, engineers and data scientists looking to learn about various vibration monitoring techniques on rotating machines would benefit from this book. It contains the most current vibration monitoring methods along with links for publicly accessible software for many of the techniques described and links to publicly available vibration data sets that can be used for testing new algorithms and neural networks.
Ferroelectric Materials for Energy Harvesting and Storage
D. Maurya, A. Pramanick, and D. Viehland, Editors
50 Hampshire Street, 5th Floor Cambridge, MA 02139 http://www.elsevier.com/books-and-
372 pp., $235 (Softcover), 2021
The internet of things (IoT) has challenged engineers to design sensors, suitable in size, cost, and performance, to monitor just about anything that a person may be interested in knowing about a particular status or health of an item, or want data for such as the strain on a bridge or the temperature of a power conductor. Although there is a huge variety of sensors with excellent performance that are small and have a low cost in many cases, these sensors and associated electronics still need to be powered. While many newly developed sensors and supporting electronics can currently operate at extremely low power requirements, as compared to legacy sensors and electronics, there is still a need for some type of power source. And although oftentimes the power levels of these new sensors may be in the milli to micro watt range, there is still that need to have a power source. This is where energy harvesting and energy storage technology could come into play. Energy harvesting uses special materials and geometries to scavenge energy for the local environment, oftentimes from sunlight, wind, temperature differences, motion, magnetic fields, electric fields, or vibration.Energy harvesting captures energy that would generally otherwise go unused. Usually relatively small amounts of energy are parasitically harvested by taking advantage of either inherent motion, magnetic fields, convective flows, wind, solar, or thermal gradients as examples. For example, a ferromagnetic core near or around a current-carrying conductor can capture energy from the magnetic field created by the flowing current and power a wireless sensor that transmits data about the current.
This book describes materials and devices used for energy harvesting that are obtained from various types of energy sources. These energy sources discussed in this book cover solar, thermal, vibration, wind, biomechanical, and stray magnetic fields. Either ferromagnetic or piezoelectric materials are used to capture the stray energy associated with each of these energy sources. For instance, examples of a biomechanical energy harvester consist of a piezoelectric material imbedded in a shoe so that when someone walks, the flexion of the shoe bends the piezoelectric materials creating a high voltage pulse to charge a capacitor. The stored energy is then used to power sensors worn by an individual. Another mechanical example described uses a MEMS cantilever beam, implanted in a human body. The sensors in the body are powered by the excited MEMS cantilever geometry by ultrasound, powering up the electronics and sending diagnostic information to a receiver located near the patient.
Mechanical motion along transmission lines galloping is another example of a power source where piezoelectric materials can be used to harvest energy from the motion and power wireless sensors, or vibration in motors. There are many examples presented that show how energy can be harvested from various applications.
Details on the various devices are covered including theory and the design equations needed to calculate the energy harvested under various conditions.
There is also a chapter on ferroelectric ceramic capacitors for electrical energy storage. Ferroelectric materials, used as dielectric, are intended to increase the energy storage properties as compared with electrochemical capacitors with the intention of achieving high-energy density and storage efficiency with good fatigue endurance and thermal stability.
This book would be of interest to electrical engineers, physicists, chemists, or material scientists working in the areas of energy harvesting or energy storage. Its wide variety of intriguing topics can get your imagination going when reading about the many interesting designs and applications that have been developed by researchers and vividly presented in this book. Readers will not only understand the fundamentals of many different types of energy harvesting possibilities but may discover the next new energy harvesting geometry or material after reading this book.
Arc Flash Hazard—Analysis and Mitigation, 2nd Edition
J. C. Das
John Wiley & Sons Ltd.
111 River Street
Hoboken, NJ 07030 http://www.wiley.com
626 pp., $145 (Hardcover), 2021
Arc flash is a hazardous condition that can occur in power distribution equipment when an unintended arc is ignited inside the switchgear. Depending on the conditions, this arc can cause devastating equipment damage and human injury including burns, puncture wounds, shock wave pressure, and electrocution. Arc flash hazards are especially dangerous when working on live equipment with protective doors opened, leaving the work exposed to the incident energy of the arc. This is why many companies will refuse to perform work on live energized equipment.
This book provides a comprehensive review of the most recent developments in the products used to detect and mitigate these hazards as well as information on the most recent arc flash standard, the IEEE 1587-2018 edition, which is used to perform arc flash hazard calculations. This most recent edition addressed concerns with the previous edition released in 2002 and provides all new equations for calculating incident energy and arc flash boundary limits.
Background in arc flash is provided including a basic description of an electrical arc, the effects of arc blasts including fire and shock hazards, personal protective equipment (PPE), and reasons for internal arcing. There are discussions on safety and prevention through improved design of switchgear, maintenance practices, and risk reduction practices. The latest IEEE 1584-2018 edition of the arc flash standard is described in detail including all the equations and the various geometries that affect the incident energy by concentrating and directing the arc blast. Step-by-step procedures are presented to show the reader how to calculate incident energy and arc flash boundaries that are used in an arc flash analysis. These calculations used bolted fault currents, which are determined from an analysis of the power circuit. This book also shows how to obtain these bolted fault values from one-line power systems schematics. There is also information showing how system grounding can affect arc flash results and calculations to show how to account for decaying short circuit values from synchronous machines (motors or generators).
A number of methods used to mitigate arc flash are also described. These cover the more traditional (passive) methods and the more recent (active) protection methods. The traditional methods cover protective relaying, breaker and fuse selection, overcurrent coordination, differential bus schemes, and zone selective interlocking (ZSI). These more “traditional” methods are used to help reduce let-through and arcing time to reduce incident energy. Another passive method, arc resistant switchgear, is described including test criteria and type classifications but without any critical details in the mechanical design used to contain the arc blast. There is, however, mention of venting and plenum design and the effects of cable connections.
The active methods cover optical arc flash sensors (but no details on the optical relays themselves and how they behave in the system). The shunting switches and a new soft-quenching device were not mentioned. Many of the methods listed in the “Recent Trends and Innovations” section cover older methods such as ZSI, maintenance mode switch, IR windows and sight glasses, and partial discharge measurements. A section on DC arc flash provides some guidelines for calculating arc flash hazards for DC systems. These rely on IEC standards because DC is not covered in the IEEE 1584 standard.
Power engineers, facility maintenance engineers, plant managers, or anyone needing to understand and use the latest information on arc flash hazards will find this book to be a very valuable resource. It is loaded with all the essentials one needs to perform an arc flash hazard analysis. It will also provide the reader with a deep appreciation of arc flash hazards.
Metal Oxide Powder Technologies— Fundamentals, Processing Methods and Applications
Y. Al-Douri, Editor
50 Hampshire Street, 5th Floor Cambridge, MA 02139 http://www.elsevier.com/books-and-
451 pp., $225 (Softcover), 2020
There are a growing number of applications for metal oxides in microelectronics, optoelectronics, biomedical, and energy technology areas. The production of metal-oxides continues to improve along with many new uses for metal oxides. This book provides the reader with the fundamental background of the theory and experiment for various metal oxides.
The book begins by reviewing the latest fundamentals of metal oxide powders including the physical and chemical characteristics. The synthesis and preparation of metal oxide powders using chemical, physical, and biological methods are introduced. Processing methods further discuss sintering behaviors of Fe3O4 and CaO powders and also include phase diagrams. Methods for modifying the surface of the oxide particles, including polymerization, nanocoating, and microencapsulation, are reviewed. Composites of metal oxides with ceramics and polymers are also discussed.
Much of the book details using metal oxides for bioimaging and antibacterial coatings and the use of nanoparticles for biomedical applications. Other applications cover energy technologies including fuel cells, capturing industrial waste gas emissions, and supercapacitors. The use of metal oxide in electronics in transistors, diodes, and photodetectors is also reviewed. Heavy metal detection and removal is another application area explored.
Solution combustion and 3D printing of ceramic powder are two other methods listed, with the last topic covering the use of metal oxides in dielectric materials. The properties and behavior of oxide mixtures with dielectrics is described for ZnO, TiO2, and other metal oxides, although there are no details on electrical applications of metal oxides in dielectrics.
This book would be of interest to researchers working with powder metal oxide technologies with a focus mainly in the areas of biomedical, ceramic matrix composites, fuel cells, and supercapacitor technology. It would also benefit those who want to learn about the latest metal oxide processing methods. There are loads of graphical and tabular data along with many micrographs used to illustrate powder size and morphology, critical factors that need to be controlled for obtaining desired properties. It is well worth the effort to obtain a copy to learn about the various processing methods.
Thermodynamics— Principles and Applications, 2nd Edition
World Scientific Publishing Co.
5 Toh Tuck Link
27 Warren Street, Suite 401-402 Hackensack, NJ 07601 http://www.worldscientificpress.com ISBN 978-981-121-706-7
533 pp., $128 (Hardcover), 2020
Thermodynamics requires the understanding of several abstract quantities, which makes thermodynamics rather difficult to understand. This book is intended to provide the fundamentals of thermodynamics to allow readers to solve practical problems pertaining to thermodynamics.
The book begins by introducing commonly used terms in thermodynamics and introduces the concepts of heat, temperature, and “state/path function”—key concepts in thermodynamics. Calculations of reversible and irreversible processes are clearly explained along with pressure-volume-temperature behavior of pure substances. The majority of the book covers, in detail, the first and second laws of thermodynamics. There is also discussion on energy conversion.
What is nice about this book is that it clearly explains theory through clear and concise writing and by providing many illustrations to help the reader understand the concepts being presented, and the examples given provide the answers to the “what if” questions. For example, if the steam temperature is increased in a boiler system, what effect does this have on the equations, and what practical implications might this have for the given application? Or, what is the effect of increasing boiler pressure on the system and the practical considerations? This method of teaching really helps the reader to understand these sometimes-difficult concepts of thermodynamics, especially with concepts such as Gibbs free energy, enthalpy, and entropy.
While not all our readers may be that interested in thermodynamics, anyone who wants to either learn about thermodynamics or get a very good refresher will find this book to be one of the best at explaining these abstract concepts.
Compendium on Electromagnetic Analysis— From Electrostatics to Photonics: Fundamentals and Applications for Physicists and Engineers, 5 Vol. Set
M. Donahue, Y. Sozer, T. Bauernfeind, and V. A. Markel, Editors
World Scientific Publishing Co. 5 Toh Tuck Link
27 Warren Street, Suite 401-402 Hackensack, NJ 07601 http://www.worldscientificpress.com ISBN 978-981-3270-16-9
$1,680 (Hardcover), 2020
The electromagnetic spectrum spans from electrostatics (DC) into the optical range and beyond. This five-volume compendium covers various aspects of electromagnetics from electrostatics to optical frequencies. It provides the theoretical background for electrostatic, magnetic, optic, and photonic behavior and provides many applications for new electric machines, antennas, and microwave devices.
Volume 1 covers Electrostatic and Magnetic Phenomena. Some topics include probing materials with electromagnetic waves, electromagnetic waves in canted magnets, modeling of nanostructured magnetic field sensors, and hard magnets. This volume is very physics oriented with new topic areas as well as background in some traditional areas.
Volume 2 covers The New Generation of Electric Machines. This volume reviews electric machine fundamentals and then delves into more recent topics, some of which include optimization of electric motors, core losses in motors, automotive electric motors, and magnetic gears and magnetically geared machines for compact and reliable high-torque, low-speed systems.
Volume 3 covers Antennas, Antenna Arrays and Microwave Devices. Some of the areas covered include solutions for Maxwell’s equations from DC to microwave frequencies, metamaterials and applications, radiative wireless energy transfer, backscatter RFID systems, and topology optimization of antennas.
Volume 4 covers Optics and Photonic I. More theory on Maxwell’s equations is provided with a focus on the optical spectrum. And for those who want more theory, Green’s functions and radiation in classical electromagnetics and electromagnetic waves in photonic crystals are reviewed. The interaction of light with gain media and radiative transport in random media are also explored.
Volume 5, Optics and Photonics II, delves into more specific applications of the theory by discussing Raman scattering, fiber lasers, a plasmon nano-laser, and various aspects of spectroscopy and optical beam applications.
This set is for graduate students in physics and engineering or photonics who want to learn about some of the latest topics in electromagnetics. If one or more of the topics in this set covers your area of interest, then this set would be worth reading. Although much of the material is very theoretical, it is written in a very accessible manner that clearly explains very in-depth technical details that may not be easily understood in a typical classroom book on electromagnetics. Being a set of five volumes would make it more suitable as a university or business library addition.
Principles of Dielectric Logging Theory
A. Kaufman and J. Donadille Elsevier
50 Hampshire Street, 5th Floor Cambridge, MA 02139 http://www.elsevier.com/books-and-journals
352 pp., $150 (Softcover), 2021
Dielectric logging is a method used in the oil and gas industry to primarily determine the water content in a borehole. The impedance and dielectric permittivity are measured using high frequency probes in boreholes to ascertain certain properties about the conditions of the materials in the well.
This book reviews the fundamental theory of dielectric permittivity as it applies to the systems and methods used for dielectric logging. Although it is applied to dielectric logging, the majority of this book focuses on general dielectric theory. This theory covers both static and time-varying electric fields, specifically for spherical and elliptical electrodes, used in dielectric logging. The theory of determining an effective permittivity as a function of time over a range of frequencies in the GHz range for polar and nonpolar materials (i.e., water + oil) is discussed. Expressions for the complex dielectric permittivity are given and used to show how they are applied to dielectric logging methods.
This background theory is used to show how to determine an effective permittivity when the dielectric consists of two layers, such as the case in the oil borehole application. Displacement currents, the distribution of volume and surface charges, and the field caused by the interface charges are all taken into account and then applied to the conditions used in borehole equipment.
The majority of this book is on dielectric theory and Maxwell’s equations used in dielectric permittivity theory, so it can be used by anyone interested in dielectric theory and permittivity in general. It also illustrates how to apply this theory under the conditions found in an oil and gas borehole.