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Special Issue "Dielectric and Electrical Insulation Measurements"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A: Electrical Engineering".

Deadline for manuscript submissions: closed (20 March 2022) | Viewed by 2921

Special Issue Editors

Dr. Refat Atef Ghunem
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Guest Editor
NRC Metrology Research Center, National Research Council Canada, Ottawa, ON, Canada‎
Special Issues, Collections and Topics in MDPI journals
Dr. Yazid Hadjadj
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Guest Editor
NRC Metrology Research Center, National Research Council, Ottawa, ON K1A 0R6, Canada
Interests: filled polymers; differential thermal analysis; erosion; silicone rubber; transformer oil; ageing; alumina; arcs (electric); combustion; electric breakdown; electric current measurement; frequency measurement; impregnated insulation; insulator testing; leakage currents; magnesium compounds; moisture measurement; nanocomposites; partial discharges; particle size; permittivity; polymer insulators; power cable insulation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Rapid technological advances over the past few decades have stimulated progress in various measurement solutions for the development and application of dielectrics and electrical insulation. In particular, different types of electrical, thermal, chemical, and spectroscopic measurements have been introduced to improve several aspects of fabrication, processing, diagnostics, reliability, aging assessment, lifetime estimation, material characterization and optimization of dielectrics and electrical insulation. These measurement advances have benefited a wide spectrum of related applications at various scales, from microencapsulation to high voltage insulation installed for bulk power delivery in the electricity grid, and potential progress in many other applications is yet to be explored. Therefore, this Special Issue focuses on shedding the light on recent measurement advances in the development, application, and lifecycle management of dielectrics and electrical insulation.

Dr. Refat Atef Ghunem
Dr. Yazid Hadjadj
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Dielectric measurements
  • Dielectric spectroscopy
  • Characterization of nanodielectrics
  • Characterization of electrical insulation
  • Insulation monitoring
  • Insulation diagnostics
  • Insulation condition assessment
  • Insulation aging analysis
  • Insulation material screening and evaluation
  • Electrical insulation testing

Published Papers (5 papers)

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Research

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Article
Improved Image Analysis Method to Evaluate Tracking Property under Successive Flashover Based on Fractal Theory
Energies 2021, 14(24), 8253; https://doi.org/10.3390/en14248253 - 08 Dec 2021
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Abstract
Successive flashover would result in carbonized tracking on insulator surface and cause deterioration to the insulation. Thus, investigation of the tracking can be beneficial in understanding flashover characteristics during long-term operation. In this paper, DC flashover was operated on the insulator, and the [...] Read more.
Successive flashover would result in carbonized tracking on insulator surface and cause deterioration to the insulation. Thus, investigation of the tracking can be beneficial in understanding flashover characteristics during long-term operation. In this paper, DC flashover was operated on the insulator, and the image of tracking after successive discharge were captured. Improved differential box-counting method (IDBM) was applied to analyze these images based on fractal theory. Weighted item was suggested during the counting procedure for rectangle image with margin covered by cut-size box. Fractal dimension of the tracking was calculated according to the suggested method. It is claimed that the suggested method could estimate the discharge propagation property and deterioration characteristics on the insulator surface. Moreover, IDBM showed advantages in image pre-processing and deterioration property revealed compared to traditional box-counting method attributing to the consideration of color depth. This image analysis method shows universality in dealing with tracking image and could provide additional information to flashover voltage. This paper suggested a potential approach for the investigation of discharge mechanism and corresponding deterioration in future research. Full article
(This article belongs to the Special Issue Dielectric and Electrical Insulation Measurements)
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Article
Evaluation of Erosion Discharge Characteristics in Inclined Plane Tracking and Erosion Tests on Silicone Rubber under AC and DC Voltages
Energies 2021, 14(19), 6051; https://doi.org/10.3390/en14196051 - 23 Sep 2021
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Abstract
This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, [...] Read more.
This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps. Full article
(This article belongs to the Special Issue Dielectric and Electrical Insulation Measurements)
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Article
A Machine-Learning Approach to Identify the Influence of Temperature on FRA Measurements
Energies 2021, 14(18), 5718; https://doi.org/10.3390/en14185718 - 10 Sep 2021
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Abstract
Frequency response analysis (FRA) is a powerful and widely used tool for condition assessment in power transformers. However, interpretation schemes are still challenging. Studies show that FRA data can be influenced by parameters other than winding deformation, including temperature. In this study, a [...] Read more.
Frequency response analysis (FRA) is a powerful and widely used tool for condition assessment in power transformers. However, interpretation schemes are still challenging. Studies show that FRA data can be influenced by parameters other than winding deformation, including temperature. In this study, a machine-learning approach with temperature as an input attribute was used to objectively identify faults in FRA traces. To the best knowledge of the authors, this has not been reported in the literature. A single-phase transformer model was specifically designed and fabricated for use as a test object for the study. The model is unique in that it allows the non-destructive interchange of healthy and distorted winding sections and, hence, reproducible and repeatable FRA measurements. FRA measurements taken at temperatures ranging from −40 °C to 40 °C were used first to describe the impact of temperature on FRA traces and then to test the ability of the machine learning algorithms to discriminate between fault conditions and temperature variation. The results show that when temperature is not considered in the training dataset, the algorithm may misclassify healthy measurements, taken at different temperatures, as mechanical or electrical faults. However, once the influence of temperature was considered in the training set, the performance of the classifier as studied was restored. The results indicate the feasibility of using the proposed approach to prevent misclassification based on temperature changes. Full article
(This article belongs to the Special Issue Dielectric and Electrical Insulation Measurements)
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Article
Characterization of Partial Discharge Activities in WBG Power Converters under Low-Pressure Condition
Energies 2021, 14(17), 5394; https://doi.org/10.3390/en14175394 - 30 Aug 2021
Cited by 2 | Viewed by 546
Abstract
Many sectors, such as transportation systems, are undergoing rapid electrification due to the need for the mitigation of CO2 emissions. To ensure safe and reliable operation, the electrical equipment must be able to work under various environmental conditions. At high altitudes, the low [...] Read more.
Many sectors, such as transportation systems, are undergoing rapid electrification due to the need for the mitigation of CO2 emissions. To ensure safe and reliable operation, the electrical equipment must be able to work under various environmental conditions. At high altitudes, the low pressure can adversely affect the health of insulating materials of electrical systems in electric aircraft. A well-known, primary aging mechanism in dielectrics is partial discharge (PD). This study targets internal PD evaluation in an insulated-gate bipolar transistor (IGBT) module under low-pressure conditions. The estimation of electric field distribution is conducted through 3D finite element analysis (FEA) using COMSOL Multiphysics®. The procedure of PD detection and transient modeling is performed in MATLAB for two pressure levels (atmospheric and half-atmospheric). The case study is the IGBT module with a void or two voids in the proximity of triple joints. The single-void case demonstrates that at half-atmospheric pressure, the intensity of discharges per voltage cycle increases by more than 40% compared to atmospheric pressure. The double-void case further shows that a void that is harmless at sea level can turn into an additional source of aging and couple with the other voids to escalate PD intensity by a factor of two or more. Full article
(This article belongs to the Special Issue Dielectric and Electrical Insulation Measurements)
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Review

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Review
Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements
Energies 2022, 15(5), 1677; https://doi.org/10.3390/en15051677 - 24 Feb 2022
Cited by 1 | Viewed by 450
Abstract
This paper discusses the state of the art in the application of self-healing silicone-based materials for outdoor high-voltage insulation. Both the dynamic behavior of the dimethyl side groups of silicone rubber and the diffusion of a bulk siloxane to maintain low surface energy [...] Read more.
This paper discusses the state of the art in the application of self-healing silicone-based materials for outdoor high-voltage insulation. Both the dynamic behavior of the dimethyl side groups of silicone rubber and the diffusion of a bulk siloxane to maintain low surface energy are respectively reported as intrinsic mechanisms responsible for the self-healing of silicone rubber. Localization, temporality, mobility, and the type of synthesis are the aspects defining the efficiency of the self-healing ability of silicone rubber. In addition, the deterioration of the self-healing ability with filler loaded into silicone rubber insulation housing composites is discussed. Taking the self-healing property into consideration among the other properties of silicone rubber insulators, such as tracking and erosion resistance, can be a useful design practice at the material development stage. Hydrophobicity retention, recovery, and transfer measurements are discussed as useful indicators of the self-healing ability of silicone rubber. Nevertheless, there remains a need to standardize them as design tests at the material development stage. The paper is intended to shed the light on the hydrophobicity recovery, a key material design parameter in the development of silicone rubber outdoor insulating composites, similar to the tracking and erosion resistance. Full article
(This article belongs to the Special Issue Dielectric and Electrical Insulation Measurements)
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