Pub Date : 2025-03-06DOI: 10.1109/TDEI.2025.3548973
Jatoth Varun;Palash Mishra;Addala Dharanish;Ayman El Hag;R. Sarathi;Mithun Mondal
The capability to transform into a flame-retardant ceramic body when encountering high temperatures makes low melting glass (LMG) powder an effective additive for room temperature vulcanized (RTV) silicone rubber composites, which are used as coating materials for outdoor high-voltage insulators operating in harsh environments. In this context, the present study examines the impact of nano LMG powder (LMGP) on the aging characteristics of 5 wt% boron nitride (BN)-doped silicone rubber nanocomposites exposed to a strong electrolytic aqueous ammonium chloride (NH4Cl) solution. LMG nanofiller was added in varying weight percentages of 3 and 7 wt%. Except for the 7 wt% LMG-doped composite, a distinct dip in weight gain, indicating higher degradation and detachment of filler particles, was noted in all the composites during diffusion test. Aging-induced deterioration of surface morphology is well evident in 3-D microscopy, contact angle, and Fourier transform infrared (FTIR) spectroscopic test results, which clearly demonstrate increased surface roughness and scissioning of side chains (Si-CH$_{{3}}text {)}$ and backbone chains (Si-O–Si) in silicone rubber matrix of all the composites postaging. Furthermore, antipollution performance and thermal properties of all the test specimens were evaluated through inclined plane tracking and erosion test, thermogravimetric analysis (TGA), and IR thermography. The test results demonstrated that LMG-doped composites showed better tracking and erosion resistance, higher thermal stability, and lower surface temperature distribution during inclined plane tracking (IPT) compared to the only BN specimen before and after aging. The experimental results revealed that the 7 wt% LMG composite exhibited better resistance to degradation caused by the NH4Cl solution.
{"title":"Aging Characteristics of Ceramifiable Silicone Rubber Nanocomposites Exposed to Electrolytic Solution","authors":"Jatoth Varun;Palash Mishra;Addala Dharanish;Ayman El Hag;R. Sarathi;Mithun Mondal","doi":"10.1109/TDEI.2025.3548973","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3548973","url":null,"abstract":"The capability to transform into a flame-retardant ceramic body when encountering high temperatures makes low melting glass (LMG) powder an effective additive for room temperature vulcanized (RTV) silicone rubber composites, which are used as coating materials for outdoor high-voltage insulators operating in harsh environments. In this context, the present study examines the impact of nano LMG powder (LMGP) on the aging characteristics of 5 wt% boron nitride (BN)-doped silicone rubber nanocomposites exposed to a strong electrolytic aqueous ammonium chloride (NH4Cl) solution. LMG nanofiller was added in varying weight percentages of 3 and 7 wt%. Except for the 7 wt% LMG-doped composite, a distinct dip in weight gain, indicating higher degradation and detachment of filler particles, was noted in all the composites during diffusion test. Aging-induced deterioration of surface morphology is well evident in 3-D microscopy, contact angle, and Fourier transform infrared (FTIR) spectroscopic test results, which clearly demonstrate increased surface roughness and scissioning of side chains (Si-CH<inline-formula> <tex-math>$_{{3}}text {)}$ </tex-math></inline-formula> and backbone chains (Si-O–Si) in silicone rubber matrix of all the composites postaging. Furthermore, antipollution performance and thermal properties of all the test specimens were evaluated through inclined plane tracking and erosion test, thermogravimetric analysis (TGA), and IR thermography. The test results demonstrated that LMG-doped composites showed better tracking and erosion resistance, higher thermal stability, and lower surface temperature distribution during inclined plane tracking (IPT) compared to the only BN specimen before and after aging. The experimental results revealed that the 7 wt% LMG composite exhibited better resistance to degradation caused by the NH4Cl solution.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"1940-1948"},"PeriodicalIF":3.1,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The reliability of high-voltage overhead lines is strongly correlated to the status of outdoor insulators, which is correlated to the condition of high-temperature vulcanized silicone rubber (HTV-SR) used as insulator sheds. Current research pays attention to HTV-SR’s degradation under different environmental stresses (e.g., temperature and corona discharge). However, the lifetime assessment of the aged HTV-SR is unclear, and the effect of temperature cycling is seldom considered. In this study, a remaining useful lifetime (RUL) prediction method for HTV-SR is proposed, which considers both temperature cycling and corona discharge. Accelerated lifetime tests of HTV-SR are conducted, and the key parameters of the model are determined by the experimental data. Thus, a formula for quantitative RUL prediction is put forward, which indicates that when the cyclic temperature is $5.5~^{circ }$ C$sim 21.3~^{circ }$ C and the electric field strength at the sample surface is 4.5 and 6.8 kV/cm, the RUL with 90% reliability is 25.9 and 8.4 years. Furthermore, verification of the prediction model is conducted using the elongation at break of field-aged insulators with different operation times. This study provides a method to estimate the RUL of HTV-SR materials, which can guide the maintenance of outdoor insulators of power transmission lines.
高压架空线路的可靠性与室外绝缘子的状态密切相关，而室外绝缘子的状态又与高温硫化硅橡胶（hhtv - sr）用作绝缘子棚的状况有关。目前的研究重点是HTV-SR在不同环境应力（如温度和电晕放电）下的降解。然而，对HTV-SR的寿命评估尚不明确，且很少考虑温度循环的影响。在本研究中，提出了一种同时考虑温度循环和电晕放电的HTV-SR剩余使用寿命预测方法。对HTV-SR进行了加速寿命试验，并根据试验数据确定了模型的关键参数。由此，提出了RUL定量预测公式，当循环温度为$5.5~^{circ}$ C $ sim为21.3~^{circ}$ C，样品表面电场强度为4.5和6.8 kV/cm时，RUL的可靠性分别为25.9和8.4年。利用不同运行次数的现场老化绝缘子断裂伸长率对预测模型进行了验证。本研究提供了一种估算HTV-SR材料RUL的方法，可以指导输电线路室外绝缘子的维护。
{"title":"Lifespan Evaluation of HTV Silicone Rubber in Outdoor Composite Insulators Considering Temperature Cycling and Corona Discharge","authors":"Shiyin Zeng;Wendong Li;Xin Zhao;Yanan Peng;Yuelin Liu;Xinyi Yan;Guanjun Zhang","doi":"10.1109/TDEI.2025.3567210","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3567210","url":null,"abstract":"The reliability of high-voltage overhead lines is strongly correlated to the status of outdoor insulators, which is correlated to the condition of high-temperature vulcanized silicone rubber (HTV-SR) used as insulator sheds. Current research pays attention to HTV-SR’s degradation under different environmental stresses (e.g., temperature and corona discharge). However, the lifetime assessment of the aged HTV-SR is unclear, and the effect of temperature cycling is seldom considered. In this study, a remaining useful lifetime (RUL) prediction method for HTV-SR is proposed, which considers both temperature cycling and corona discharge. Accelerated lifetime tests of HTV-SR are conducted, and the key parameters of the model are determined by the experimental data. Thus, a formula for quantitative RUL prediction is put forward, which indicates that when the cyclic temperature is <inline-formula> <tex-math>$5.5~^{circ }$ </tex-math></inline-formula>C<inline-formula> <tex-math>$sim 21.3~^{circ }$ </tex-math></inline-formula>C and the electric field strength at the sample surface is 4.5 and 6.8 kV/cm, the RUL with 90% reliability is 25.9 and 8.4 years. Furthermore, verification of the prediction model is conducted using the elongation at break of field-aged insulators with different operation times. This study provides a method to estimate the RUL of HTV-SR materials, which can guide the maintenance of outdoor insulators of power transmission lines.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"2403-2412"},"PeriodicalIF":3.1,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-26DOI: 10.1109/TDEI.2025.3546175
Anna Drzewicz;Michael Wübbenhorst
The miniaturization of devices causes an increase in scientists’ interest in the possibility of creating and characterizing ultrathin layers of liquid crystals. Using organic molecular beam deposition (OMBD), organic thin layers are produced in ultrahigh vacuum by single molecule deposition on a cold substrate. In this article, we verify the possibility of creating thin films of liquid crystal below the glass transition temperature by the OMBD method. We also investigated the effect of various OMBD deposition parameters on the layer thickness and the $alpha $ -relaxation dynamics of the compound under study. Some striking differences in relaxation dynamics related to glass-forming behavior are observed in ultrathin films compared to the bulk. We show that real time, in situ dielectric relaxation spectroscopy can be successfully applied to study the dynamic glass transition in geometric confinement, not only for simple glass-forming liquids but also for glass-forming liquid crystals using OMBD.
{"title":"Ultrathin Films of Liquid Crystal Obtained via Organic Molecular Beam Deposition Method","authors":"Anna Drzewicz;Michael Wübbenhorst","doi":"10.1109/TDEI.2025.3546175","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3546175","url":null,"abstract":"The miniaturization of devices causes an increase in scientists’ interest in the possibility of creating and characterizing ultrathin layers of liquid crystals. Using organic molecular beam deposition (OMBD), organic thin layers are produced in ultrahigh vacuum by single molecule deposition on a cold substrate. In this article, we verify the possibility of creating thin films of liquid crystal below the glass transition temperature by the OMBD method. We also investigated the effect of various OMBD deposition parameters on the layer thickness and the <inline-formula> <tex-math>$alpha $ </tex-math></inline-formula>-relaxation dynamics of the compound under study. Some striking differences in relaxation dynamics related to glass-forming behavior are observed in ultrathin films compared to the bulk. We show that real time, in situ dielectric relaxation spectroscopy can be successfully applied to study the dynamic glass transition in geometric confinement, not only for simple glass-forming liquids but also for glass-forming liquid crystals using OMBD.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 3","pages":"1631-1638"},"PeriodicalIF":2.9,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-24DOI: 10.1109/TDEI.2025.3545010
May Thin Khaing;Koki Watanabe;Tatsuya Sakoda;Toru Takayama;Kazunori Miyazaki
A residual charge method is useful for measuring water tree in 22-kV crosslinked polyethylene (XLPE) cable systems. However, the conventional residual charge method cannot locate a water-tree degraded cable section because the time-resolved signal response from a water-tree degradation section cannot be obtained. In this study, we inject a sine wave pulse with a frequency of 1 MHz into measuring object cables when ac voltage is applied to the cables to release trapped charges due to the water-tree. We examine to locate a water-tree degraded cable section in 22-kV XLPE cable systems, including water-tree degraded cables and a Y-branch cable joint. The time-resolved residual charges induced by the voltage pulse induced by an injection coil (IJ coil) can locate a water-tree degraded cable section.
{"title":"Locating Water-Tree Degraded Cable Section by Measuring Residual Charges Induced by Voltage Pulse Wave","authors":"May Thin Khaing;Koki Watanabe;Tatsuya Sakoda;Toru Takayama;Kazunori Miyazaki","doi":"10.1109/TDEI.2025.3545010","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3545010","url":null,"abstract":"A residual charge method is useful for measuring water tree in 22-kV crosslinked polyethylene (XLPE) cable systems. However, the conventional residual charge method cannot locate a water-tree degraded cable section because the time-resolved signal response from a water-tree degradation section cannot be obtained. In this study, we inject a sine wave pulse with a frequency of 1 MHz into measuring object cables when ac voltage is applied to the cables to release trapped charges due to the water-tree. We examine to locate a water-tree degraded cable section in 22-kV XLPE cable systems, including water-tree degraded cables and a Y-branch cable joint. The time-resolved residual charges induced by the voltage pulse induced by an injection coil (IJ coil) can locate a water-tree degraded cable section.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 5","pages":"2915-2921"},"PeriodicalIF":3.1,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145189982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-24DOI: 10.1109/TDEI.2025.3542349
Asya Viraneva;Maria Marudova;Bissera Pilicheva;Aleksandar Grigorov;Nikolay Zahariev;Sofia Milenkova;Temenuzhka Yovcheva
Polyelectrolyte multilayers (PEMs) films containing benzydamine hydrochloride (Benz)-loaded casein nanoparticles are developed aiming to increase the structure drug loading efficiency and to prolong the drug release. The multilayers are built on biodegradable polyester substrates, which are previously charged in a corona discharge. Medium viscosity sodium alginate (SA) is used as a partner in the multilayer formulation. The SA and the casein nanoparticles are deposited on the substrate using the layer-by-layer (LbL) deposition technique. The drug loading efficiency and the release kinetics in artificial saliva are determined spectrophotometrically.
{"title":"Benzydamine-Loaded Casein Nanospheres Embedded in Polyelectrolyte Multilayers","authors":"Asya Viraneva;Maria Marudova;Bissera Pilicheva;Aleksandar Grigorov;Nikolay Zahariev;Sofia Milenkova;Temenuzhka Yovcheva","doi":"10.1109/TDEI.2025.3542349","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3542349","url":null,"abstract":"Polyelectrolyte multilayers (PEMs) films containing benzydamine hydrochloride (Benz)-loaded casein nanoparticles are developed aiming to increase the structure drug loading efficiency and to prolong the drug release. The multilayers are built on biodegradable polyester substrates, which are previously charged in a corona discharge. Medium viscosity sodium alginate (SA) is used as a partner in the multilayer formulation. The SA and the casein nanoparticles are deposited on the substrate using the layer-by-layer (LbL) deposition technique. The drug loading efficiency and the release kinetics in artificial saliva are determined spectrophotometrically.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 3","pages":"1599-1605"},"PeriodicalIF":2.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-20DOI: 10.1109/TDEI.2025.3543337
Zhou Li;Fanrong Wang
As one of the most important equipment in the power system, it is of great significance to conduct fault diagnosis research on transformers. Aiming at the problem of difficult selection of parameters for support vector machine (SVM) in transformer fault diagnosis, a fault diagnosis model based on the improved pelican optimization algorithm (IPOA) optimized SVM is proposed. First, the standard pelican optimization algorithm (POA) is enhanced by introducing the Tent chaotic mapping, Levy flight strategy, and adaptive weighting strategy, and the superiority of the IPOA algorithm is verified by comparing its performance with other intelligent algorithms across four test functions. Second, feature dimensionality reduction of the data samples is performed using kernel principal component analysis (KPCA), and the IPOA algorithm is used to optimize the SVM parameters and then establish the transformer fault diagnosis model based on IPOA-SVM. Finally, the POA-SVM, northern goshawk optimization (NGO)-SVM, GWO-SVM, whale optimization algorithm (WOA)-SVM, and particle swarm optimization (PSO)-SVM models are used to conduct comparative experiments with the proposed method. The results show that the diagnostic accuracy of the IPOA-SVM model reaches 95%, which is 3.75%, 5.0%, 6.25%, 7.5%, and 8.75% higher than that of the POA-SVM, NGO-SVM, GWO-SVM, WOA-SVM, and PSO-SVM diagnostic models, respectively; and the proposed model exhibits better stability and greater adaptability.
{"title":"A Method of Kernel Principal Component Analysis and Machine Learning Algorithms for Fault Diagnosis of Power Transformers","authors":"Zhou Li;Fanrong Wang","doi":"10.1109/TDEI.2025.3543337","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3543337","url":null,"abstract":"As one of the most important equipment in the power system, it is of great significance to conduct fault diagnosis research on transformers. Aiming at the problem of difficult selection of parameters for support vector machine (SVM) in transformer fault diagnosis, a fault diagnosis model based on the improved pelican optimization algorithm (IPOA) optimized SVM is proposed. First, the standard pelican optimization algorithm (POA) is enhanced by introducing the Tent chaotic mapping, Levy flight strategy, and adaptive weighting strategy, and the superiority of the IPOA algorithm is verified by comparing its performance with other intelligent algorithms across four test functions. Second, feature dimensionality reduction of the data samples is performed using kernel principal component analysis (KPCA), and the IPOA algorithm is used to optimize the SVM parameters and then establish the transformer fault diagnosis model based on IPOA-SVM. Finally, the POA-SVM, northern goshawk optimization (NGO)-SVM, GWO-SVM, whale optimization algorithm (WOA)-SVM, and particle swarm optimization (PSO)-SVM models are used to conduct comparative experiments with the proposed method. The results show that the diagnostic accuracy of the IPOA-SVM model reaches 95%, which is 3.75%, 5.0%, 6.25%, 7.5%, and 8.75% higher than that of the POA-SVM, NGO-SVM, GWO-SVM, WOA-SVM, and PSO-SVM diagnostic models, respectively; and the proposed model exhibits better stability and greater adaptability.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 5","pages":"3068-3077"},"PeriodicalIF":3.1,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-20DOI: 10.1109/TDEI.2025.3544165
Xi Pang;Peng Liu;Pengfei Zhang;Zongliang Xie;Tianlei Xu;Dingxin Wei;Zongren Peng
The long-term synergistic effects of high-voltage direct current (HVDC) and temperature gradients inevitably stimulate charge accumulation in gas-insulated transmission line (GIL) insulators, which significantly increases the risk of insulation failure. Due to the limitations in charge measurement techniques, it is crucial to develop effective methods for accurately simulating and evaluating the dynamic charge behaviors of GIL insulators under complex operating conditions. In this study, we present a 2-D bipolar charge transport and interaction (2-D BCTI) model that accounts for both space charge and surface charge dynamics. Such a model is employed to investigate the charge behaviors of HVDC GIL insulators under varying electric fields, polarization time, and voltage polarities. Our findings indicate that higher voltages and extended polarization time lead to increased charge migration and localized accumulation within the insulator. Further analysis reveals that the surface potential at the high-voltage terminal interface is predominantly influenced by the tangential current (${J}_{text {s}}$ ) along the insulator’s surface and bulky current (${J}_{text {v}}$ ) passing through the insulator. In other regions of the basin insulator, such as the shielding ring and grounding terminal, ${J}_{text {s}}$ is the dominant factor. This study provides valuable theoretical insights into the interaction between surface and space charge, offering a foundation for optimizing the insulation design of HVDC GIL systems.
{"title":"Two-Dimensional Charge Characteristics in HVDC GIL Insulators: A Simulation Study","authors":"Xi Pang;Peng Liu;Pengfei Zhang;Zongliang Xie;Tianlei Xu;Dingxin Wei;Zongren Peng","doi":"10.1109/TDEI.2025.3544165","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3544165","url":null,"abstract":"The long-term synergistic effects of high-voltage direct current (HVDC) and temperature gradients inevitably stimulate charge accumulation in gas-insulated transmission line (GIL) insulators, which significantly increases the risk of insulation failure. Due to the limitations in charge measurement techniques, it is crucial to develop effective methods for accurately simulating and evaluating the dynamic charge behaviors of GIL insulators under complex operating conditions. In this study, we present a 2-D bipolar charge transport and interaction (2-D BCTI) model that accounts for both space charge and surface charge dynamics. Such a model is employed to investigate the charge behaviors of HVDC GIL insulators under varying electric fields, polarization time, and voltage polarities. Our findings indicate that higher voltages and extended polarization time lead to increased charge migration and localized accumulation within the insulator. Further analysis reveals that the surface potential at the high-voltage terminal interface is predominantly influenced by the tangential current (<inline-formula> <tex-math>${J}_{text {s}}$ </tex-math></inline-formula>) along the insulator’s surface and bulky current (<inline-formula> <tex-math>${J}_{text {v}}$ </tex-math></inline-formula>) passing through the insulator. In other regions of the basin insulator, such as the shielding ring and grounding terminal, <inline-formula> <tex-math>${J}_{text {s}}$ </tex-math></inline-formula> is the dominant factor. This study provides valuable theoretical insights into the interaction between surface and space charge, offering a foundation for optimizing the insulation design of HVDC GIL systems.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 5","pages":"3039-3048"},"PeriodicalIF":3.1,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145189969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1109/TDEI.2025.3543806
Juan M. Gonzalez;Leon K. Rodrigues;Filippos Beza-Florentin;Claudiu Butnaru;Mariusz Mikula;Ana Neves;João V. Sarrico
This study presents a comprehensive exploration of the thermal aging of hairpin stators from a newly commissioned assembly line, tailored for automotive applications. The novelties in this article include a methodological approach that preserves material and process representativeness by testing stators directly from production. To increase sample size and stress the turn-to-turn failure mode, the star point connection is removed. Accelerated thermal aging is achieved by selecting the most aggressive set of temperatures, and expediting thermal index (TI) calculations without compromising accuracy. A detailed examination of the control parameters in the diagnostic sub-cycle is undertaken, including visual inspection, withstand voltage, capacitance, and step-by-step (SBS) impulse test with partial discharge inception voltage detection. Winding capacitance emerges as a crucial variable for tracking sample degradation, with its aging trend influenced by the measurement voltage. The introduction of the Physics of Failure (PoF) prompts an investigation into the impregnation resin as a potential factor contributing to the relatively low attained TI. The fault isolation process is generalized in a flowchart applicable to various motor types, extending its utility beyond the automotive domain.
{"title":"A Methodology for Accelerated Thermal Aging of an Automotive Hairpin Stator","authors":"Juan M. Gonzalez;Leon K. Rodrigues;Filippos Beza-Florentin;Claudiu Butnaru;Mariusz Mikula;Ana Neves;João V. Sarrico","doi":"10.1109/TDEI.2025.3543806","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3543806","url":null,"abstract":"This study presents a comprehensive exploration of the thermal aging of hairpin stators from a newly commissioned assembly line, tailored for automotive applications. The novelties in this article include a methodological approach that preserves material and process representativeness by testing stators directly from production. To increase sample size and stress the turn-to-turn failure mode, the star point connection is removed. Accelerated thermal aging is achieved by selecting the most aggressive set of temperatures, and expediting thermal index (TI) calculations without compromising accuracy. A detailed examination of the control parameters in the diagnostic sub-cycle is undertaken, including visual inspection, withstand voltage, capacitance, and step-by-step (SBS) impulse test with partial discharge inception voltage detection. Winding capacitance emerges as a crucial variable for tracking sample degradation, with its aging trend influenced by the measurement voltage. The introduction of the Physics of Failure (PoF) prompts an investigation into the impregnation resin as a potential factor contributing to the relatively low attained TI. The fault isolation process is generalized in a flowchart applicable to various motor types, extending its utility beyond the automotive domain.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 4","pages":"2195-2204"},"PeriodicalIF":3.1,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1109/TDEI.2025.3543792
Xiaobo Meng;Lin Lin;Hao Li;Hongwei Mei;Liming Wang
The external insulation of the equipment in the valve hall of ultra high voltage (UHV) dc converter station must be able to withstand ac-dc combined voltage influences. Investigating the surface discharge characteristics of external insulation under ac-dc combined voltage is currently a significant research topic. The investigation into the surface streamer characteristics under ac-dc combined voltage is instrumental in elucidating the mechanism of surface flashover. The streamer characteristics of different phases in a single cycle under ac-dc combined voltage were determined by conducting surface streamer discharge tests. The relationship between surface streamer characteristics and different phases under ac-dc combined voltage was summarized. By comparing the test results of surface streamer discharge under dc voltage, this study analyzed the effect mechanism of ac-dc combined voltage on surface streamer characteristics. The directional motion of space charge under ac-dc combined voltage was identified as the primary determinant of surface streamer characteristics.
{"title":"Characteristic of Surface Streamer Discharge Under the AC–DC Composite Voltage","authors":"Xiaobo Meng;Lin Lin;Hao Li;Hongwei Mei;Liming Wang","doi":"10.1109/TDEI.2025.3543792","DOIUrl":"https://doi.org/10.1109/TDEI.2025.3543792","url":null,"abstract":"The external insulation of the equipment in the valve hall of ultra high voltage (UHV) dc converter station must be able to withstand ac-dc combined voltage influences. Investigating the surface discharge characteristics of external insulation under ac-dc combined voltage is currently a significant research topic. The investigation into the surface streamer characteristics under ac-dc combined voltage is instrumental in elucidating the mechanism of surface flashover. The streamer characteristics of different phases in a single cycle under ac-dc combined voltage were determined by conducting surface streamer discharge tests. The relationship between surface streamer characteristics and different phases under ac-dc combined voltage was summarized. By comparing the test results of surface streamer discharge under dc voltage, this study analyzed the effect mechanism of ac-dc combined voltage on surface streamer characteristics. The directional motion of space charge under ac-dc combined voltage was identified as the primary determinant of surface streamer characteristics.","PeriodicalId":13247,"journal":{"name":"IEEE Transactions on Dielectrics and Electrical Insulation","volume":"32 3","pages":"1373-1379"},"PeriodicalIF":2.9,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1109/TDEI.2025.3543794
Ji Liu;Pengfei Wang;Chao Zhang;Zuning Huang;Longfei Zhang;Zhen Li
In modern power systems, the proportion of epoxy/glass fiber (EP/GF) composites that served as the primary insulation composites in electrical equipment is steadily increasing. These devices suffer long-term electrical, thermal, and vibrational stresses during operation, leading to degradation and finally insulation failures. However, the underlying electrical-thermal–vibrational aging mechanisms of the dc breakdown performance of EP/GF composites remain unclear. In this work, combined electrical-thermal–vibrational aging experiments (1080 h) were performed on the prepared EP/GF composites. Infrared spectrum, dielectric spectrum, surface potential decay (SPD), and breakdown tests were used to characterize the functional groups, side-chain dynamics, trap levels, and dc breakdown strength of aged EP/GF composites. The research indicates that after long-term aging, the dc breakdown strength of EP/GF composites first increases by 5.8% at 72 h and then decreases by 20.6% at 1080 h. The aging of EP/GF composites is divided into recrosslinking and degradation stages. The recrosslinking stage enhances the dc breakdown strength of the EP/GF composites by reducing free volume before 72 h. While in the degradation stage, chain breaking and oxidation of epoxy chains steadily occur, introducing abundant short chains and polar groups (carbonyl and ester groups), improving free volume fraction, and accelerating chains’ dynamic. The improved free volume fraction accelerates electron avalanche in the electric field, stimulating charges to escape from traps and causing dc breakdown strength to considerably decrease during 72–1080 h.
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