First and foremost, I am very grateful to have been selected as a recipient of the 2023 DEIS Graduate Fellowship. This opportunity allowed me to expand my research beyond the primary scope of my PhD and gain valuable insights into current trends in the field of dielectrics and insulation systems.
High-voltage cables rated around 6 kV, insulated with cross-linked polyethylene (XLPE), are widely used to distribute electric power. To prevent power outages caused by insulation failure in these cables, it is crucial to accurately assess the deterioration state due to the growth of water trees. For this purpose, direct-leakage-current testing has been widely applied as a diagnostic method. Although the situation is likely similar in other countries, 6-kV-class distribution cables extend over vast distances throughout Japan, and many companies are involved in their maintenance. This article introduces a current tester that complies with the conditions of Japanese power distribution lines and maintenance and diagnostic standards, and is user-friendly for maintenance companies.
Cross-linked polyethylene (XLPE) is a foundational insultion material for modern high-voltage insulation systems and power equipment because it combines low dielectric loss with robust mechanical integrity [1], [2]. However, long-term service under strong electric fields, elevated temperature, and mechanical stress can trigger progressive damage, such as micro-cracking, corona-induced degradation, and electrical treeing, that may ultimately develop into serious equipment failure and safety hazards [3]. This challenge is further exacerbated by the irreversible curing of XLPE, as damage to the permanent network makes in situ self-healing difficult and restricts end-of-life recycling largely to energy recovery or down-cycling [4].
Almost everyone likes to get positive feedback that work they have done is appreciated. One would think that this recognition would come from management of their company or institution. This is sometimes the case, but sometimes it is not—because the immediate goals of the organization may not be focused on what you have accomplished. In the case of service awards, some companies think that volunteer time spent with professional associations is better spent on one's work.
The article describes how a robust classification system can be set up and evaluated using the example of typical partial discharges in gas-insulated DC systems.
The tensile strength properties of an insulating paper are provided for room (21°C) to elevated temperature (295°C) in laboratory air.
The IEEE Dielectrics and Electrical Insulation Society (DEIS) Young Professionals (YP) and Women in Engineering (WIE) representatives Moein Borghei and Sneha Satish Hegde participated in the 2026 IEEE YP/WIE/SAC/LM Joint Meeting, held from March 6 to 8 at the Royal Sheraton Riverside Hotel in Bangkok, Thailand. The meeting brought together volunteers and leaders from across IEEE Organizational Units (OU), offering a valuable space for learning, collaboration, and exchanging ideas (Figure 1).
This article reviews seven major techniques for measuring charge carrier mobility in solid insulating dielectrics, comparing their operating principles, applicable material systems, practical limitations, and future prospects for reliable charge-transport characterization.
The “triple junction” (TJ) point where a metal electrode, an insulating material, and gas (or vacuum) meet has been one of the most widely known problem for the prevention of discharge. Surface discharge at the TJ point is easily triggered as the electric field distortion and charge accumulation at TJ significantly lower the partial discharge inception voltage (PDIV). These junctions are considered to be the weakest points in gas insulated switchgear (GIS), gas insulated transmission lines (GIL), and other equipment [1]–[2].
Organic polymer insulating materials have been used for electrical insulation for many years. The electrodes of electric power equipment and electronic devices are almost always made of metal. The thermal expansion coefficient of polymers is about one order of magnitude higher than that of metals. This becomes a problem when temperatures change. In addition, the thermal conductivity of polymers is about three orders of magnitude lower than that of metals. This is a problem in preventing temperature increase in the equipment. To address these issues, composite insulation, which contains large amounts of inorganic insulators, called fillers, dispersed in polymers, has long been used.
In our latest profile, Dr. Akiko Kumada discusses her path from an electrical engineering student at the University of Tokyo to president of the IEEE Dielectrics and Electrical Insulation Society (DEIS). She also shares her love of working in a field where the distance between theory and real-world application can be remarkably short, and where collaboration transcends boundaries.
The IEEE Dielectrics and Electrical Insulation Society (DEIS) continues to grow as a global community at the intersection of materials, systems, and emerging electrification technologies. In my role as vice president–administrative, I would like to share how our administrative and operational efforts support this growth and help advance the DEIS mission. In close collaboration with our president, Prof. Akiko Kumada, and the DEIS Executive Committee, we are working to align our administrative efforts with the Society's strategic vision and evolving global priorities, including the ongoing transformation of energy systems and electrification technologies.
This article introduces a methodology for the quantitative determination of partial-discharge-related power losses induced by high-voltage harmonics, with particular emphasis on the role of the phase angle in either amplifying or attenuating these loss components.
The pursuit of enhanced transformer drying and degassing methods, focusing on effectiveness, efficiency, and environmental concerns and circular economy, has spurred the development of innovative procedures. This article provides comprehensive tutorials and critical analyses on these advancements.
The traction power supply system is the critical infrastructure of modern rail transportation and continuously provides electric energy for electric trains through the sliding contact between the pantograph and the catenary, as shown in Figure 1(a). During train operation, stable contact within the pantograph-catenary system (PCS) is crucial for ensuring a secure electrical energy supply. Excessive contact force (CF) intensifies mechanical wear on the pantograph carbon strip and the contact wire. Insufficient CF can lead to PCS offline arcing, which can further threaten the power supply safety. With increasing train speed, operational density, and operational complexity, the contact state of PCS becomes a key subject with more pronounced dynamic coupling of multiple factors. Consequently, the global rail transit industry has proposed higher demands on the stable operation and maintenance of PCS, particularly in terms of online monitoring technologies, precise maintenance capabilities, and active safety assurance, as illustrated in Figure 1(b). Currently, the safety and reliability of traction power supply systems are facing technological demands for continuous enhancement. Relevant research and engineering practices are driving progress from multiple dimensions, working together to address challenges under complex operating conditions and ensure sustained stability and secure power supply.
In Japan, overall electricity demand had remained almost constant, or even dropped slightly, for a long time until 2023, thanks to the progress of energy conservation measures. However, this situation is about to change drastically. This is because the progress in green transformation (GX) and digital transformation (DX) is driving an increase in large-scale electricity demand for data centers (DC), semiconductor factories, and the decarbonization of factories, including conversion to electric furnaces for steel production.
The city of Chengdu, home of giant pandas and spicy Sichuan cuisine, was the host to the electrical insulation community for the 31st International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) from September 21 to 26, 2025. The event, impeccably organized by Sichuan University (chaired by Shenli Jia) and technically sponsored by the IEEE Dielectrics and Electrical Insulation Society (DEIS) along with sponsorship from key industry leaders, brought together 288 researchers, engineers, and students from across Asia, Europe, and the Americas.
Practical experiences with a thermal classification test according to IEC 60034-18-31 and considerations regarding the test voltage level and mechanical stress are discussed in the context of specimen design and total duration of the investigations.
Global research uses nano- and microparticles to produce innovative insulation for winding insulation, electromobility, anticorona paint, transformer insulation, and bushings. Scientific, multifunctional research on materials provided the engineering data required to design manufacturable insulation. This article overviews the holistic approach needed to successfully develop insulation materials by examining specific insulation systems from recent research.
Dielectric materials play an important role not only in power and electrical equipment, but also in electronic and communication equipment. One type of communication equipment, now rarely used at least for long-distance applications but important until recently, is coaxial cable. Foamed and expanded polyethylene was used as the insulating material for this coaxial cable. Because the relative dielectric constant or permittivity of air is approximately 1.0, the lowest of all substances, the dielectric constant can be kept low by foaming the polymeric insulating material. As electromagnetism teaches us, electric energy or information, whether electricity or electromagnetic waves, is transmitted not through a conductor but through the conductor's insulation. The square root of the above relative dielectric constant is the refractive index, or the inverse ratio of the velocity of light or electromagnetic waves in a material to the velocity in a vacuum. Therefore, the application of insulating resins with a low dielectric constant to corresponding equipment is important to increase the speed of information transmission and communication. Toward the realization of a society with high-speed 5G/6G communications, insulating materials used in laminates and other materials are required to have a lower dielectric constant and dissipation factor to reduce transmission loss and increase transmission speed in the high-frequency band. For the these reasons, many resin manufacturers are actively working on developing insulating resins with a low dielectric constant for 5G/6G communications.
