Electrical Insulation of Conformally Coated Printed Circuit Boards: An Overview and a Study of the Influence of Pollution
Ehsan Zeynali; Ryan Bridges; Behzad Kordi — Xplore Link
A New Approach to Partial Discharge Detection Under DC Voltage: Application to Different Materials
Pietro Romano; Antonino Imburgia; Giuseppe Rizzo; Guido Ala; Roberto Candela — Xplore Link
Investigation of High-Frequency Oscillation Discrepancies Presented by Distribution Transformers During Lightning-Impulse Voltage Tests
M. P. Pereira; G. H. Faria; J. P. Villibor; G. P. Lopes; E. T. W. Neto — Xplore Link
John Fothergill, Alun Vaughan, Peter Morshuis, and Thomas Andritsch
DEIS Summer School organizers
The DEIS Summer School: How It All Started
In a 2014 daydream, a very simple idea came to us: suppose we bring together a group of bright young people and involve them in a three-day brainstorm on a topic they can relate to—what are the chances of coming out with no results? It is a rhetorical question indeed, or so one would think.
In our proposal to the DEIS AdCom, one of the arguments used to invite DEIS to sponsor the event was: “To promote scientific debate and the exchange of ideas in the field of electrical insulation and dielectrics, the IEEE DEIS organizes a summer school in June 2015. The main purpose is to encourage a discussion between a group of junior researchers and PhD students on three related hot topics in dielectrics research.” Simple enough…
So, on the 19th of June 2015, three of us set out for Bologna, a beautiful city with one of the oldest universities in Europe. While we were thinking about how to shape the meeting, students and early career researchers from all over the world arrived. On the 21st we drove by coach to the castle on top of the hill in the medieval village of Bertinoro. This would be our home for the next three days, as it once was for Frederick Barbarossa, holy Roman emperor from 1155 to 1190.
One may wonder why we took the trouble of organizing the meeting in such a relatively remote location. Well, the main reason was that we wanted to meet in a quiet place, a place of contemplation with no distractions from the outside world … and where there was no way to “escape.” What better place than a medieval castle? This would remain an important condition for the summer schools in the following years.
Paying homage to the concept of the “Autrans” workshops in France, started by Steve Rowe and John Fothergill in 2005, the summer school was organized in a novel way. The three-day program consisted of interactive brainstorm sessions with a limited number of introductory lectures given by the organizers. This interactive approach was chosen to place the students at the center of the event so that they would develop novel ideas to achieve a breakthrough in the field of dielectric interfacial phenomena. Moreover, the exchange of ideas among students of different backgrounds was thought to be an added value in the brainstorms.
After a few plenary introductions, the students were divided into three groups, each group led by one of the three musketeers (as the students later started calling us). In a quite natural and organic manner, we decided to act more as observers and interfere with the brainstorms as little as possible.
On the first day, each group raised important issues and uncertainties in the field of nanodielectrics. Plenary discussions were initiated by providing the students with a list of relevant questions related to the nature of nanometric fillers and their interaction with the host polymeric matrix. Moreover, more general topics, such as the existence of interfaces and interphases around nanoparticles, were discussed as well. Finally, some provocative contradictions and paradoxes about dielectric behavior at the nanoscale were suggested. Thus, the students gradually got to know each other better and became more familiar with the topics, which were relatively novel for some of them. At the end of the day, during a plenary session, the groups presented the results of their brainstorms, and plans of action for the next day were made.
On day two, the groups were challenged to define a proposition about the behavior of interfaces at the nanoscale. Following this, possible experiments were defined with the aim of confirming or rejecting the hypothesis made in the proposition.
Finally, on the last day, the groups were challenged to prepare a research program that would allow them to further explore their ideas, even after the end of the summer school.
From day one, the idea was to plant the seed for “something” during the summer school, something that would further develop after the meeting in Bertinoro had finished. The immersion of the students in a scientific brainstorm was just one element. It was also envisaged that the students would build a network among themselves and aim for some future collaborations. They were also offered the opportunity to organize a special session at one of the DEIS international conferences and, in 2016, they duly presented an evening session at the IEEE International Conference on Dielectrics in Montpellier, France.
When we evaluated this first summer school, we came to the following conclusions:
1. Within one day, any barriers between moderators and students had disappeared;
2. The brainstorm process was positively affected by the moderators staying in the background;
3. The students benefited from an introduction on how to define a research project, starting with the definition of a proper research question; and
4. Within the short period of just three days, groups of early stage researchers that had never met before were interacting openly and were able to define joint research programs.
With this first summer school, we had thrown ourselves into the proverbial deep end. Apart from general aims and the introductory lectures, there had been no detailed preparation of the event—we strongly believed that we needed to focus on the needs of the students, which would only become apparent as the event progressed. What we did was improvise, keeping in mind that stimulating an open discussion was most important. The challenge was not to interfere too much and only push and shove a little bit if absolutely needed. It was a risk, but there was never a doubt that we would be successful in some way.
The Next Five Years
The first summer school was a success, from the perspective of the organizers and the students. So, we looked at each other and said: “let’s do it again!” In 2016 Xi’an Jiaotong University in China co-hosted the event in a small cultural heritage village in Fufeng, not far from the Famen Temple, one of the largest Buddhist temples in China. This time there were four of us, the four musketeers. All the students were Chinese, and halfway through the first day we had become quite desperate. How do we break down cultural and social barriers and have the students engage in the discussion? With a few tricks, we were able to change the situation within one hour. We still don’t know exactly what happened, but the situation changed. This strengthened our feeling that our flexible, responsive summer school concept would probably work for all cultures. As was the case in Bertinoro, by the end of the summer school, networks had been formed and many new friends had been made.
In the following years, we went to Japan (2017) and back again to Bertinoro (2018). By 2019 we decided to change the main topic of the summer school to “extra-high-voltage DC: challenges for science and technology.” But, equally important, we extended the summer school by two days during which a selection of international experts was invited to discuss these challenges with the students. It was really refreshing to see the interaction between the two groups.
We had decided to continue the summer school with the topic of HVDC in 2020, but we were stopped in our tracks by the pandemic.
In total, 144 students from 18 different countries have participated in the five summer schools held thus far. The concept we devised in 2015 proved to be successful and worthy of repeating in the following years, each time, further refining and fine tuning the way we interact with the participants. We learned that even in the short period of three days, networks can be built and progress can be made in engaging early stage researchers in scientific brainstorms that actually lead to something. Since 2015 the summer school participants have organized several sessions at international conferences and many of them still work together in some way or another.
In August 2021, hoping that world-wide vaccination will make travel possible again, we plan to host the DEIS summer school in Monmouth, Wales, where our venue will be Monmouth School, which was founded in 1614. So, it’s not quite a medieval castle, but a historic and beautiful location nonetheless, situated in one of the UK’s designated areas of outstanding natural beauty and with links to such diverse characters as the mythical King Arthur; the very real Charles Rolls, of Rolls Royce fame; and Freddie Mercury. In January more information will be made available about the event.
Although the way we, the four musketeers, operate is to a large extent determined by our personalities, our summer school concept should not be linked to us only. Indeed, for its long-term success it must not be linked to us only. There is a lot of space for other summer schools in different places in the world. We are convinced that many more early stage researchers can be reached. And, obviously, there are many different topics that can be considered for a brainstorm, although in our case, the mechanism and dynamics of the summer school process are at least as important as the topic.
If, and only if, a situation can be created in which there are no barriers between the students and the teachers/moderators, we believe our summer school concept will work. We are gladly prepared to share our experiences and assist any other DEIS musketeers in the world who would like to organize a summer school.
One for all and all for one!
Peter Morshuis, Alun Vaughan, John Fothergill, and Thomas Andritsch
The four musketeers
From The Editor
While I am writing this, on the 3rd of January in the new year, I cannot help but think about the people from our community whom we lost in 2020, be it due to COVID-19 or other causes. Let us hope that 2021 will be better, for all of us, and that gradually we will be able to meet with each other again in person. I really miss the talks during our conferences’ coffee breaks, moments that I’m sure many of you cherish as well.
This issue of the Magazine was produced over Christmas, and I thank the editorial board for their continued support, even during a time they would have rather spent with their family and friends. The featured articles cover a broad range of topics and are focused on the effects of pollution on the integrity of insulating materials used for printed circuit boards, an alternative method of DC partial discharge testing, and the origin of high frequency oscillations in distribution transformers.
The first article is titled “Electrical Insulation of Conformally Coated Printed Circuit Boards: An Overview and a Study of the Influence of Pollution.” It is written by Ehsan Zeynali and Behzad Kordi from the University of Manitoba, Canada, and Ryan Bridges from Manitoba Hydro, Canada.
It provides an overview of the insulation coating of printed circuit boards (PCB) and discusses the various types of conformal coating materials and their method of application. The standard test methods used to evaluate the performance of coated PCBs are described in some detail. To determine the effects of pollution on the integrity of the PCB coating, experiments were performed on silicone-coated specimens for which the partial discharge behavior and breakdown characteristics were determined. Experiments confirmed that the location of the pollution plays an important role in the partial discharge activity and the occurrence of momentary discharges on a coated PCB. Breakdown voltage tests under different test conditions confirmed enhanced insulation properties for coated samples even at low air pressure.
The second article in this issue presents the results of a new method for measuring partial discharge in DC equipment using a waveform that is partly sinusoidal and partly DC. It is titled “A New Approach to Partial Discharge Detection Under DC Voltage: Application to Different Materials.” It is authored by a team from the high voltage laboratory of Palermo University, Italy, consisting of Pietro Romano, Antonino Imburgia, Giuseppe Rizzo, and Guido Ala, and Roberto Candela from Prysmian Electronics, Palermo, Italy. In the article the authors further elaborate on a technique they recently introduced to facilitate the measurement of partial discharge activity in DC equipment. By applying a waveform that is part AC and part DC, they propose a method (DCP) that results in an electric field distribution in the specimen under test similar to a DC voltage with the added advantage that the AC part of the waveform triggers more easily partial discharge activity. The DCP method was used on specimens using different types of insulation with an artificially introduced cavity. The expected electric field distributions were simulated numerically, and it was shown that similar internal surface charge densities were to be expected for DCP and for a pure DC voltage. Phase-resolved partial discharge measurements were used to study partial discharge inception voltage and phase patterns. The DCP method was shown to detect the presence of partial discharge activity at relatively low test voltages, far below DC partial discharge inception.
The third article is titled “Investigation of High-Frequency Oscillation Discrepancies Presented by Distribution Transformers During Lightning-Impulse Voltage Tests,” written by M. P. Pereira, G. H. Faria, J. P. Villibor, G. P. Lopes, and E. T. W. Neto from the high voltage laboratory of the Federal University of Itajubá, Brazil. The authors made a comprehensive study on high frequency oscillations obtained during impulse voltage testing of distribution transformers. The main objective was to identify the cause of the high-frequency oscillation discrepancies registered in the impulse oscillograms. It is verified that these discrepancies are associated with the presence of partial discharges measured before the lightning-impulse test. The authors show that the minor discrepancies only in small high-frequency oscillations were caused by partial discharge, due to internal imperfections of the transformer. It was found that these discrepancies caused by internal imperfections did not generate changes in the results of the follow-up tests. It is stipulated that such imperfections can however evolve in the field and cause damage to the insulation of the transformer. The paper recommends manufacturers and purchasers of distribution transformers to make more use of partial discharge tests to identify these imperfections and improve the insulation quality of distribution transformers.
News from Japan
John J. Shea
Wireless Connectivity: An Intuitive and Fundamental Guide
John Wiley & Sons Inc.
111 River Street
Hoboken, NJ 07030
407 pp., €79.10 (Hardcover), 2020
Wireless communication has become a way of life today. Many people use cell phones to communicate either via talk or text. The mobile cell phone has developed into an indispensable communication medium and information system with many far-reaching applications. Furthermore, the development of wire- less technology continues to expand in possibilities with the introduction of 5G communications, expanded Wi-Fi, and the internet of things connectivity.
This book provides a look into explaining some of the most important ideas and concepts used in wireless connectivity and explains how these devices are interconnected.
The book jumps right into shared wireless systems and the issues and challenges with various protocols. The author focuses mainly on cellular technologies and short message systems (SMS) without describing one particular company or specific devices but rather conveys the concept and keeps the descriptions generic. He also keeps mathematics to a minimum, which is especially nice for those who want to have an accessible, fast-reading book with the concepts rather than a highly technical design handbook, although some communication theory is presented.
Some of the topics described cover various aspects of modern communication methods explained in a simple straight-forward manner. The main areas cover how communication space is shared among many devices, network communication protocols, packet communication, how to overcome noise and lost data for reliable communications, channel capacity time and frequency constraints, antenna requirements, and the various types of connections and networks.
With the ubiquity of wireless communications and the ever-expanding rate of proliferation of this technology, anyone looking to understand how wireless communications work will find this book to be a great start for understanding the most current methods used in today’s wireless technologies because it does not delve into excruciating technical equations but rather provides great insight into the concepts and methods. More specifically, electrical communication engineering students, practicing wireless engineers who want a broader understanding of their field, computer scientists, and even engineers working in unrelated areas but who may use wireless devices in their designs will find this book an excellent resource for advancing their knowledge of current new technology.
Analysis of Grounding and Bonding Systems
Taylor & Francis Group
6000 Broken Sound Parkway–NW, Suite 300
Boca Raton, FL 33487-2742
168 pp., $175 (Hardcover), 2020
Proper grounding is essential for electrical safety in power distribution networks. The National Electrical Code (NEC) in the United States as well as other national standards in other countries are used to provide uniform safety standards for electrical power distribution systems. Standard methods are mandated but not often explained as to why a certain method is used. This book can add to your understanding of the physics behind grounding and bonding of electrical systems, which can help to explain the methods and reasons behind national standards.
This book provides the theory behind grounding and bonding systems. It covers the basics of grounding electrodes (rods, sphere, and grounding grids), uniform and non-uniform soil resistivity for fault protection, and electrical shock safety through proper bonding of electrical equipment. The reader will learn about the technical details of ground impedance and the various types of grounding systems and ground electrode layout and design and methods used to connect to existing building infrastructure (pipes, beams, etc.), touch voltages, and touch currents for human body safety in different types of grounding systems (TT, TN, IT).
In addition to these fundamental topics, there are two additional focus areas discussed—heat networks and electric vehicles (EVs). The heat network topic describes methods used to properly connect grounding from one, centrally located heat-generating building to separate buildings using the water pipes as grounding connections.
The EV section describes grounding and protection methods used for electric shock and fault protection while charging an EV and fault protection while driving. Also described are class II chargers and extra-low-voltage chargers.
Engineers, especially power engineers who design power distribution systems, will find this book to be especially useful for helping to understand the reasons behind the choices made in the national electrical standards. It provides outstanding technical detail that clearly illustrates the physics and operation of grounding and bonding systems in general, and the reader can apply their new knowledge to better understand the standards. While the author does not reference specific electrical codes, he does refer to reasons why certain things are done the way they are in the code to help the reader better understand the standards.
The Fundamentals and Applications of Light Emitting Diodes—The Revolution in the Lighting Industry
G. B. Nair and S. J. Dhoble
50 Hampshire Street, 5th Floor Cambridge, MA 02139
284 pp., $215 (Softcover), 2020
Light emitting diode (LED) lamps are quickly replacing conventional lighting and are also enabling many new applications such as vertical indoor agriculture, medical uses for skin therapy, display technologies, digital communication, and entertainment. This book examines many new lighting applications enabled by LED technology along with details on LED fabrication, LED design and construction, spectral properties, and an introduction to luminance and color rendering.
While the technical details on materials and how LEDs are manufactured to produce different wavelengths is worth reading about, the most interesting area covers the many new applications enabled by LED lighting. Besides the many general lighting applications discussed and the challenges that LEDs had to overcome to displace traditional light sources, there are a number of other application areas also described. Some of these include using specific wavelength LEDs to correct skin disorders including scars, wrinkles, skin coloring, and acne treatments. Other applications discuss indoor vertical agriculture and the use of LEDs to better replicate the sun as compared to high intensity discharge (HID) lamps, which produced a great amount of heat as well as have other issues. Other application areas describe digital communications and display devices.
Current trends and innovations in structure and design of LEDs are also briefly described as are new emerging applications. Other alternative LED materials (advanced variants) are also described including micro-LEDs, organic and quantum dot LEDs, perovskite and bio-LEDs.
While mainly intended for engineers and those with a technical background, anyone wanting to learn more about the applications of LEDs in the lighting industry and the limitations for LEDs would find this book very interesting. There are also an extensive number of references in each chapter for more in-depth study.
Optical Properties of Materials and Their Applications, 2nd Edition
J. Singh, Editor
John Wiley & Sons Inc.
111 River Street
Hoboken, NJ 07030 http://www.wiley.com
667 pp., $265 (Hardcover), 2020
The development and advancement of electro-optic materials has led to many new applications such as LED lighting, organic LED displays, renewable energy technologies, quantum dots, radiation detectors, and many others. This book is a compilation of work, in the optical and electro-optical fields, written by many contributing experts in their respective specialties. The book is intended for the study of optical properties of materials with a focus on electro-optical materials or materials used in electro-optical applications. It is written for academia as well industrial researchers developing opto-electronic materials and photonics.
The first half of the book describes many fundamental processes associated with electro-optics and, as such, can be used for those needing to learn fundamentals. Although basic information such as refractive index is explained, many more in-depth applications and more narrow applications that are useful currently are also presented such as transmittance of thin film with nonuniform thickness. Some of the other topics, for example, cover refractive index, reflectance of thin films with nonuniform thickness, lattice absorption, band-to-band absorption, optical properties of glasses, the concept of excitons, and photo-luminescence. Material behavior is described in general as well as for specific materials using fundamental theoretical descriptions with some experimentally measured material properties.
The second half of this book mainly details various applications of electro-optic materials. Some examples include applications of quantum dots, perovskites in photovoltaic and LEDs, and magnetic semiconductor nanostructures.
This theoretical review of optical properties and material behavior characterization of electro-optical and photonic materials would appeal to material scientists, chemists, and researcher developing new electro-optical materials. They can learn about some of the most recent developments in electro-optics. Students who want to learn more about this field could also benefit from this book because there is a large percentage of the book devoted to fundamentals.
Wireless Internet of Things: Principles and Practice
World Scientific Publishing Co.
5 Toh Tuck Link
27 Warren Street
Hackensack, NJ 07601 http://www.worldscientificpress.com
715 pp., $88 (Softcover), 2020
The internet of things (IoT) can be defined as a system of interrelated, internet-connected objects that are able to collect and transfer data over a wireless network without human intervention. This book focuses on the principles and technologies implemented in the physical infrastructure that enables the IoT. It consists of the authors notes, developed over the last 12 years of teaching wireless communication courses at universities in Australia and New Zealand. This textbook is clearly a valuable resource for engineering students or anyone who wants to learn about wireless communication since it provides the technical fundamentals of the key theories and methods used for IoT communication.
Some of these key topics covered are modulation methods, radio wave propagation, antennas, multiplexing, design of mobile wireless networks, microwave systems, radar and satellite communication, and wireless positioning technology. Each chapter is clearly written, with mathematics kept to a minimum, and when used, thoroughly explained. There is at least one worked-out example in each chapter and numerous review questions to check and reinforce knowledge. There is also a very handy website available that contains any updated errata, PowerPoint slides of each chapter, PDF files of all figures and tables in the book, and an online forum that you can join.
If you interested in learning about the technical details of IoT and wireless communication, then this very well-written book, loaded with the fundamentals for understanding this rapidly growing system of the future, is well-worth reading.
Crystal Growth for Beginners—Fundamentals of Nucleation, Crystal Growth, and Epitaxy,
World Scientific Publishing Co. 5 Toh Tuck Link
27 Warren Street
Hackensack, NJ 07601 http://www.worldscientificpress.com
630 pp., $148 (Hardcover), 2017
This is a book for those who want to learn about the theoretical aspects of crystal growth. Crystal growth is used in applications for creating micro-electronics, opto-electronics, and material science for example. The book covers the fundamentals of crystal nucleation, growth, and epitaxy.
It is divided into four sections—equilibrium, nucleation, crystal growth, and epitaxial growth. The first section on equilibrium sets the stage for the remaining sections because this section provides the background on which all the other sections are based. It defines basic equilibrium theory necessary to understand crystal nucleation, growth, and epitaxy.
Section two on nucleation, presents the thermodynamic reaction equations and rate equations to initiate nucleation. The formation of a new phase requires the appearance of small clusters of building blocks (atoms or molecules) on the substrate surface. Using equilibrium equations, the author shows various examples of nucleation under many different conditions.
Section three, crystal growth, describes conditions necessary for desired crystal growth including layers growth of flat faces, vapor phase growth, liquid phase growth, and nucleation growth.
Section four, epitaxy, or the growth of one type of crystal on the surface of a material different from the crystal, describes basic concepts and definition of epitaxy along with mechanisms for the growth of epitaxial films and the thermodynamics of epitaxy.
Although fairly theoretical but still accessible to those with basic mathematics and chemistry background, this book offers the reader who wants to learn about the fundamentals of crystal growth a good way to get introduced to this important area of research that supports the latest developments in electronics and materials technologies.
Organometallic Luminescence—A Case Study on AlQ3, an OLED Reference Material
50 Hampshire Street, 5th Floor Cambridge, MA 02139
351 pp., $200 (Softcover), 2021
Alq3, (Tris(8-hydroxyquinoline) aluminum (III)) or C27H18AlN3O3, is an or- ganic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes (OLEDs) and a host for fluorescent and phosphorescent dyes. Organic optoelectronic materials continue to be studied by many research groups, one of which is Alq3 material. This book presents the author’s research, based on many years of experimentation, with Alq3 materials for luminescence applications. It describes a method, based on photoluminescence, to visualize the optical proper- ties of Alq3 including its absorption and long decay times from both a theoretical and experimental approach.
The book starts with the physical and chemical properties of Alq3 and descriptions of sample preparation, characterization, and storage. The majority of the book then describes the many experimental results the author obtained for the absorption and emission characteristic of Alq3 thin-film materials. There are also discussions summarizing the results and the potential for Alq3 materials for use as an OLED.
This book is a unique reference book on Alq3 materials. It includes lists of references for further study and loads of graphical data showing the properties obtained for Alq3 under various conditions. Those readers interested in OLED materials, specifically Alq3 OLED materials, would enjoy this book.