Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341874
T. Aakre, E. Ildstad
Condition assessment of generators is today performed at various voltage frequencies and test temperatures. The main purpose of this paper is to compare measured PD results from sections of generator bars with that of similar tests performed on laboratory made test objects with void enclosures of known geometry. The test objects were subjected to ac voltage in the frequency range from 0.1 to 300 Hz, increasing in steps up to a maximum of 10 kV. The measured values of partial discharge inception voltages (PDIV), apparent charge magnitude and number of PDs were compared to estimated values in the temperature range of 20° to $155^{circ}mathrm{C}$ using an impedance abcmodel, including both conduction and dielectric response. It was found that the capacitive abc-model sufficiently accurately describes the observed PDIV values at temperatures below $100^{circ}mathrm{C}$ and test frequencies below 50 Hz. At temperatures higher temperatures the measured PDIV values were found to decrease with increasing temperature, particularly so at the lowest test frequencies. This is in agreement with the assumption of increased conductivity and higher rate of polarization at increased temperatures. The high number of low magnitude PDs, strongly indicating that several discharges are needed for a complete discharge of a void surface.
{"title":"PD-Activity in Generator Stator Bar insulation versus Voltage Frequency and Temperature","authors":"T. Aakre, E. Ildstad","doi":"10.1109/ICD46958.2020.9341874","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341874","url":null,"abstract":"Condition assessment of generators is today performed at various voltage frequencies and test temperatures. The main purpose of this paper is to compare measured PD results from sections of generator bars with that of similar tests performed on laboratory made test objects with void enclosures of known geometry. The test objects were subjected to ac voltage in the frequency range from 0.1 to 300 Hz, increasing in steps up to a maximum of 10 kV. The measured values of partial discharge inception voltages (PDIV), apparent charge magnitude and number of PDs were compared to estimated values in the temperature range of 20° to $155^{circ}mathrm{C}$ using an impedance abcmodel, including both conduction and dielectric response. It was found that the capacitive abc-model sufficiently accurately describes the observed PDIV values at temperatures below $100^{circ}mathrm{C}$ and test frequencies below 50 Hz. At temperatures higher temperatures the measured PDIV values were found to decrease with increasing temperature, particularly so at the lowest test frequencies. This is in agreement with the assumption of increased conductivity and higher rate of polarization at increased temperatures. The high number of low magnitude PDs, strongly indicating that several discharges are needed for a complete discharge of a void surface.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"1 1","pages":"870-873"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83561522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341930
M. Ferraris, T. J. Murray, M. Viola
European regulation changes have pushed electric machine manufacturers to request new materials suitable for impregnation of High Voltage motors and generators that are also compliant with European health restrictions. Until now, the most widely used materials for coils insulation are a blend of epoxy resin and anhydride that impregnates mica tapes, containing an epoxy binder with a Zinc naphthenate catalyst, which has the advantage of stability in storage tanks and good thermal and electrical properties. The development of a new impregnating resin, made with a hybrid epoxy-polyester chemistry, highlighted the need to find a way to improve compatibility with mica tapes. This new resin / tape combination has been visually evaluated, as first step, and then tested on bars, observing how dissipation factor versus voltage change after thermal ageing at high temperatures. Test bars made with new resin/tape combination withstood thermal ageing for a longer time than reference materials, confirming that compatibility between impregnating resin and mica tapes is a crucial factor influencing thermal resistance of a coil main wall insulation system.
{"title":"New chemistry for impregnation of HV machines: influence of compatibility between resin and mica tapes","authors":"M. Ferraris, T. J. Murray, M. Viola","doi":"10.1109/ICD46958.2020.9341930","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341930","url":null,"abstract":"European regulation changes have pushed electric machine manufacturers to request new materials suitable for impregnation of High Voltage motors and generators that are also compliant with European health restrictions. Until now, the most widely used materials for coils insulation are a blend of epoxy resin and anhydride that impregnates mica tapes, containing an epoxy binder with a Zinc naphthenate catalyst, which has the advantage of stability in storage tanks and good thermal and electrical properties. The development of a new impregnating resin, made with a hybrid epoxy-polyester chemistry, highlighted the need to find a way to improve compatibility with mica tapes. This new resin / tape combination has been visually evaluated, as first step, and then tested on bars, observing how dissipation factor versus voltage change after thermal ageing at high temperatures. Test bars made with new resin/tape combination withstood thermal ageing for a longer time than reference materials, confirming that compatibility between impregnating resin and mica tapes is a crucial factor influencing thermal resistance of a coil main wall insulation system.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"35 1","pages":"685-688"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86438373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341809
Chengxing Lian, Xu Zhang, C. Emersic, I. Cotton
The accretion of ice and pollution can lead to serious damage and failure of overhead line systems during icing events. CIGRE TB361 has detailed a family of advanced coatings which claim to be superhydrophobic or ice repellent and which can be deployed on power system equipment to reduce ice accumulation. This paper examines the performance of a commercial superhydrophobic coating NeverWet on aluminium alloy substrates. This coating achieved an average contact angle of 169.5° and the lowest sliding angle of 1.5°. A series of ageing tests were designed and conducted, including thermal ageing/cycling, corona exposure, ultraviolet exposure, and ambient outdoor exposure. The superhydrophobicity of samples was retained after all ageing tests with the exception of corona exposure.
{"title":"Ageing Behaviours of Superhydrophobic and Icephobic Coatings on Overhead Line Systems","authors":"Chengxing Lian, Xu Zhang, C. Emersic, I. Cotton","doi":"10.1109/ICD46958.2020.9341809","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341809","url":null,"abstract":"The accretion of ice and pollution can lead to serious damage and failure of overhead line systems during icing events. CIGRE TB361 has detailed a family of advanced coatings which claim to be superhydrophobic or ice repellent and which can be deployed on power system equipment to reduce ice accumulation. This paper examines the performance of a commercial superhydrophobic coating NeverWet on aluminium alloy substrates. This coating achieved an average contact angle of 169.5° and the lowest sliding angle of 1.5°. A series of ageing tests were designed and conducted, including thermal ageing/cycling, corona exposure, ultraviolet exposure, and ambient outdoor exposure. The superhydrophobicity of samples was retained after all ageing tests with the exception of corona exposure.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"02 1","pages":"138-141"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91265890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341831
Y. Wang, Ang Li, J. Li, W. Zhang, Q. Du, M. M. Zhang, Z. H. Wang, H. C. Liang, B. Du
With the increase of transmission voltage and capacity, epoxy resin for high-voltage electrical equipment was facing great challenges, and the modification of resin materials has become an important topic in current research. This paper summarized the modification methods of epoxy resin for high-voltage electrical apparatus in recent years and introduced the progress of epoxy resin in toughening modification, high heat resistance, high thermal conductivity, and electrical property regulation, and respectively discussed the modification methods of epoxy resin. The modification methods of epoxy resin were studied, which provide a certain reference for developing the epoxy resin with excellent performance.
{"title":"Research Progress on Modification of Epoxy Resin Materials for High-Voltage Electrical Equipment","authors":"Y. Wang, Ang Li, J. Li, W. Zhang, Q. Du, M. M. Zhang, Z. H. Wang, H. C. Liang, B. Du","doi":"10.1109/ICD46958.2020.9341831","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341831","url":null,"abstract":"With the increase of transmission voltage and capacity, epoxy resin for high-voltage electrical equipment was facing great challenges, and the modification of resin materials has become an important topic in current research. This paper summarized the modification methods of epoxy resin for high-voltage electrical apparatus in recent years and introduced the progress of epoxy resin in toughening modification, high heat resistance, high thermal conductivity, and electrical property regulation, and respectively discussed the modification methods of epoxy resin. The modification methods of epoxy resin were studied, which provide a certain reference for developing the epoxy resin with excellent performance.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"8 6","pages":"637-640"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91407240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341949
S. Haller, Damien Bachellerie, S. Pruvost, Loriane Desmars, S. Iglesias, J. Galy, G. Robert, Christian Lao, A. Girodet, M. Henriksen
Hexagonal Boron Nitride (hBN) has been used as secondary filler in an epoxy formulation in gas insulated substation (GIS) demonstrating higher electrical performance under HVAC stress, while being compatible with industrial process and constraints. A synergetic effect between hBN and alumina has been observed regarding thermal and electrical properties. A 500% increase in the thermal conductivity could be achieved with a limited impact on viscosity increase. Breakdown strength has been measured in flat sheets in oil and with embedded electrodes under divergent field simulating a defect. The breakdown strengths resulting from these different experimental setups show an interesting barrier effect from hBN even at low ratio in the formulation. Both results can be correlated with increased lifetime under thermoelectrical stress.
{"title":"Epoxy composite with hBN fillers compatible with industrial application in electrical equipment","authors":"S. Haller, Damien Bachellerie, S. Pruvost, Loriane Desmars, S. Iglesias, J. Galy, G. Robert, Christian Lao, A. Girodet, M. Henriksen","doi":"10.1109/ICD46958.2020.9341949","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341949","url":null,"abstract":"Hexagonal Boron Nitride (hBN) has been used as secondary filler in an epoxy formulation in gas insulated substation (GIS) demonstrating higher electrical performance under HVAC stress, while being compatible with industrial process and constraints. A synergetic effect between hBN and alumina has been observed regarding thermal and electrical properties. A 500% increase in the thermal conductivity could be achieved with a limited impact on viscosity increase. Breakdown strength has been measured in flat sheets in oil and with embedded electrodes under divergent field simulating a defect. The breakdown strengths resulting from these different experimental setups show an interesting barrier effect from hBN even at low ratio in the formulation. Both results can be correlated with increased lifetime under thermoelectrical stress.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"34 1","pages":"590-593"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90721214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341966
Hucheng Liang, B. Du, Jin Li, R. Zhao, Zehua Wang, Miaomiao Zhang, Ang Li, Q. Du
To reduce the electric field (E-field) distortion in a gassolid insulating system, a centrifugation technique is proposed to fabricate the interfacial E-field regulating (IER) insulator. During the curing process of the liquid epoxy/SiC mixture in the mold, a centrifugal force was used to force the SiC particles to the insulator surface, forming a uniform thin surface layer of nonlinear conductivity. After fabrication, electrical evaluations, including numerical simulations and flashover tests, were conducted to verify the E-field regulating effect of the novel insulator. As the thickness of the nonlinear-conductivity layer increases, the maximum E-field in the flashover region of the novel insulator declines and converges to a stable value, but the surface conduction loss continues growing. The flashover voltages of the novel insulator are improved by ~13% and ~21% under positive and negative voltages, respectively. By applying such novel insulators, a higher reliability and compacter structure can be realized for the DC-GIL.
{"title":"Interfacial E-field Regulating Insulator for DC Gas-solid Insulating System","authors":"Hucheng Liang, B. Du, Jin Li, R. Zhao, Zehua Wang, Miaomiao Zhang, Ang Li, Q. Du","doi":"10.1109/ICD46958.2020.9341966","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341966","url":null,"abstract":"To reduce the electric field (E-field) distortion in a gassolid insulating system, a centrifugation technique is proposed to fabricate the interfacial E-field regulating (IER) insulator. During the curing process of the liquid epoxy/SiC mixture in the mold, a centrifugal force was used to force the SiC particles to the insulator surface, forming a uniform thin surface layer of nonlinear conductivity. After fabrication, electrical evaluations, including numerical simulations and flashover tests, were conducted to verify the E-field regulating effect of the novel insulator. As the thickness of the nonlinear-conductivity layer increases, the maximum E-field in the flashover region of the novel insulator declines and converges to a stable value, but the surface conduction loss continues growing. The flashover voltages of the novel insulator are improved by ~13% and ~21% under positive and negative voltages, respectively. By applying such novel insulators, a higher reliability and compacter structure can be realized for the DC-GIL.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"268 1","pages":"297-300"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77970907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341977
Xin Zhao, Siyi Zhang, Cheng-lu Lin, Zhi Yang, Zhonglei Li, T. Han
Cross-linked polyethylene (XLPE) plays a significant role in AC power cables. In the cables, the difference in temperatures of conductor and surrounding environment produces a temperature gradient in XLPE, and the electrical and thermal aging accelerate the degradation. When defects exist in the dielectric, an electrical tree may be initiated. Hence, it is necessary to research the electrical tree in XLPE under the temperature gradient. In this paper, XLPE samples were tested under 50 Hz AC voltage with multiple temperature gradients, and the electrical tree was recorded by a digital microscope. To simulate an electrical stress concentration, a pair of needle-plate electrodes was utilized in this experiment. There are two types of temperature gradients in this experiment, one is to set the needle electrode temperature to 100 °C and increase the ground electrode temperature from 30 to 70 °C, and the other is the opposite. The tree structure, growth process, fractal dimension, accumulated damage and tree length were recorded and analyzed. The experiment results indicate that the temperature gradient affects the growth rate and the structure of trees. When the ground electrode temperature is higher than the needle tip, the tree grows faster. The fractal dimension and the accumulated damage increase as the temperature gradient increases.
{"title":"Characterization of Electrical Treeing in XLPE versus Temperature Gradients","authors":"Xin Zhao, Siyi Zhang, Cheng-lu Lin, Zhi Yang, Zhonglei Li, T. Han","doi":"10.1109/ICD46958.2020.9341977","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341977","url":null,"abstract":"Cross-linked polyethylene (XLPE) plays a significant role in AC power cables. In the cables, the difference in temperatures of conductor and surrounding environment produces a temperature gradient in XLPE, and the electrical and thermal aging accelerate the degradation. When defects exist in the dielectric, an electrical tree may be initiated. Hence, it is necessary to research the electrical tree in XLPE under the temperature gradient. In this paper, XLPE samples were tested under 50 Hz AC voltage with multiple temperature gradients, and the electrical tree was recorded by a digital microscope. To simulate an electrical stress concentration, a pair of needle-plate electrodes was utilized in this experiment. There are two types of temperature gradients in this experiment, one is to set the needle electrode temperature to 100 °C and increase the ground electrode temperature from 30 to 70 °C, and the other is the opposite. The tree structure, growth process, fractal dimension, accumulated damage and tree length were recorded and analyzed. The experiment results indicate that the temperature gradient affects the growth rate and the structure of trees. When the ground electrode temperature is higher than the needle tip, the tree grows faster. The fractal dimension and the accumulated damage increase as the temperature gradient increases.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"23 1","pages":"25-28"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78032953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341807
Jinjing Peng, Yu Gao, Jing Li, Xuri Xu, Zheng Song, B. Du
Polypropylene (PP) has been considered as a promising insulation material for power cable in both AC and DC systems because of its excellent insulation performance and recyclability. The exposure to partial discharge gives rise to the deterioration of the material that threatens the safe operation of cable. Therefore, it is of great significance to understand the mechanism of partial discharge of PP and its blends subjected to AC voltage. In this work, PP/elastomer blends with thickness of $150 mu mathrm{m}$ were prepared as samples. A needle-plane electrode system was employed to introduce partial discharge by applying an AC voltage with 5 kVrms for 2 hours. The erosion behavior was characterized through multi-sensors system, including high frequency current transformer (HFCT), optical recorder and gas sensor. To better understand the erosion mechanism, isothermal surface potential decay (ISPD) method was used to analyze trap characteristics. The results showed that the trap center became shallower with the increase of elastomer content for both ethylene-octene copolymer elastomer (EOC) and polypropylene based elastomer (PBE). Compared with pure PP, the addition of elastomer improved the resistance of partial discharge and PP with 20 wt% loading percent of EOC presented better resistance to partial discharge compared with PP with 20 wt% loading percent of PBE.
聚丙烯(PP)由于其优良的绝缘性能和可回收性，被认为是一种很有前途的交、直流电力电缆绝缘材料。暴露在局部放电环境下会导致材料劣化，威胁电缆的安全运行。因此，了解PP及其共混物在交流电压作用下局部放电的机理具有重要意义。本研究制备了厚度为$150 mu mathm {m}$的PP/弹性体共混物作为样品。采用针平面电极系统，施加5 kVrms交流电压2小时，引起局部放电。利用高频电流互感器(HFCT)、光学记录仪和气体传感器等多传感器系统对腐蚀行为进行了表征。为了更好地了解侵蚀机理，采用等温表面电位衰减(ISPD)方法分析了陷阱特征。结果表明，随着弹性体含量的增加，乙烯-辛烯共聚物弹性体(EOC)和聚丙烯基弹性体(PBE)的陷阱中心变浅;与纯PP相比，弹性体的加入提高了PP的局部放电性能，而含20%重量% EOC的PP比含20%重量% PBE的PP具有更好的局部放电性能。
{"title":"Partial Discharge Erosion of Polypropylene/Elastomer Blends Characterized with Multi-Sensors under AC Voltage","authors":"Jinjing Peng, Yu Gao, Jing Li, Xuri Xu, Zheng Song, B. Du","doi":"10.1109/ICD46958.2020.9341807","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341807","url":null,"abstract":"Polypropylene (PP) has been considered as a promising insulation material for power cable in both AC and DC systems because of its excellent insulation performance and recyclability. The exposure to partial discharge gives rise to the deterioration of the material that threatens the safe operation of cable. Therefore, it is of great significance to understand the mechanism of partial discharge of PP and its blends subjected to AC voltage. In this work, PP/elastomer blends with thickness of $150 mu mathrm{m}$ were prepared as samples. A needle-plane electrode system was employed to introduce partial discharge by applying an AC voltage with 5 kVrms for 2 hours. The erosion behavior was characterized through multi-sensors system, including high frequency current transformer (HFCT), optical recorder and gas sensor. To better understand the erosion mechanism, isothermal surface potential decay (ISPD) method was used to analyze trap characteristics. The results showed that the trap center became shallower with the increase of elastomer content for both ethylene-octene copolymer elastomer (EOC) and polypropylene based elastomer (PBE). Compared with pure PP, the addition of elastomer improved the resistance of partial discharge and PP with 20 wt% loading percent of EOC presented better resistance to partial discharge compared with PP with 20 wt% loading percent of PBE.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"95 1","pages":"890-893"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85723348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9342021
E. Matić, M. Meissner, S. Schober, M. Mittelbach
Insulation liquids perform a vital role in protecting power equipment, such as transformers, from thermal, electrical and environmental stress. Considering the poor fire-safety properties and low biodegradability of mineral oil as the leading kind of insulation liquid, alternative insulation liquids are of high interest for their implementation in power equipment. In this experiment we aimed to simulate the processes occurring in faulty power equipment by ageing four different kinds of insulation liquids (mineral oil, GTL-insulation liquid, synthetic ester and natural ester) under laboratory conditions. The use of optimized analytical routine methods has allowed us to monitor as well as quantify volatile acid and polymer formations upon ageing of insulation liquids. The ageing process under aerated conditions has led to the formation of formic, acetic and propionic acid, especially in natural ester, alongside notable polymerization effects. All other types of insulation liquids showed significantly lower amounts of volatile acids. Per contra, the experiments conducted under oxygen-free conditions resulted in minimal volatile acid and polymer build-ups in all four insulation liquids.
{"title":"Volatile Acid and Polymer Formation in Various Insulation Liquids Upon Accelerated Thermal Ageing","authors":"E. Matić, M. Meissner, S. Schober, M. Mittelbach","doi":"10.1109/ICD46958.2020.9342021","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9342021","url":null,"abstract":"Insulation liquids perform a vital role in protecting power equipment, such as transformers, from thermal, electrical and environmental stress. Considering the poor fire-safety properties and low biodegradability of mineral oil as the leading kind of insulation liquid, alternative insulation liquids are of high interest for their implementation in power equipment. In this experiment we aimed to simulate the processes occurring in faulty power equipment by ageing four different kinds of insulation liquids (mineral oil, GTL-insulation liquid, synthetic ester and natural ester) under laboratory conditions. The use of optimized analytical routine methods has allowed us to monitor as well as quantify volatile acid and polymer formations upon ageing of insulation liquids. The ageing process under aerated conditions has led to the formation of formic, acetic and propionic acid, especially in natural ester, alongside notable polymerization effects. All other types of insulation liquids showed significantly lower amounts of volatile acids. Per contra, the experiments conducted under oxygen-free conditions resulted in minimal volatile acid and polymer build-ups in all four insulation liquids.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"49 1","pages":"317-320"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80719830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-05DOI: 10.1109/ICD46958.2020.9341925
M. Fan, Zhonglei Li, B. Du, S. Zhou
Polypropylene (PP) is regarded as a recyclable alternative to XLPE for cable insulation on account of its higher heat resistance and higher electrical resistivity. The dielectric relaxation and trap level characteristics of isotactic PP (iPP), syndiotactic PP (sPP) as well as atactic PP (aPP) blends are investigated. The associations between polymer polarization response and traps level characteristics of PP blends are discussed. Frequency-domain dielectric spectroscopy (FDS) methods are used to analyze the polarization response of five PP blends at 50, 70 and 90 0C. Isothermal surface potential decay (ISPD) tests are performed to acquire the traps level distribution and the influences of traps level characteristics on the dielectric response are discussed. The polymer polarization behaviours a and $delta$ of five samples is closely related to segmental movements and carriers hopping behaviours, separately. The intensity of a relaxation strength ($Deltavarepsilon_{a}$) declines with the increase of sPP content, because the related coefficient (g) between PP molecular chains is reduced. The calculated energy $E_{tau}$ for $delta$ process is in proportion to the shallow traps level, because the shallow traps with a higher level increase the potential barriers of carriers hopping behaviors. The increase in temperature causes the dipole to undergo intense Brownian motion in the electric field, resulting in a decrease in $Deltavarepsilon_{a}$ with increasing temperature. The thermal motion of the charge increases the mobility of carriers in the PP and causes $Deltavarepsilon_{delta}$ to increasewith increasingtemperature.
{"title":"Effect of sPP Content on Dielectric Relaxation and Trap Level Characteristics of PP blend insulation","authors":"M. Fan, Zhonglei Li, B. Du, S. Zhou","doi":"10.1109/ICD46958.2020.9341925","DOIUrl":"https://doi.org/10.1109/ICD46958.2020.9341925","url":null,"abstract":"Polypropylene (PP) is regarded as a recyclable alternative to XLPE for cable insulation on account of its higher heat resistance and higher electrical resistivity. The dielectric relaxation and trap level characteristics of isotactic PP (iPP), syndiotactic PP (sPP) as well as atactic PP (aPP) blends are investigated. The associations between polymer polarization response and traps level characteristics of PP blends are discussed. Frequency-domain dielectric spectroscopy (FDS) methods are used to analyze the polarization response of five PP blends at 50, 70 and 90 0C. Isothermal surface potential decay (ISPD) tests are performed to acquire the traps level distribution and the influences of traps level characteristics on the dielectric response are discussed. The polymer polarization behaviours a and $delta$ of five samples is closely related to segmental movements and carriers hopping behaviours, separately. The intensity of a relaxation strength ($Deltavarepsilon_{a}$) declines with the increase of sPP content, because the related coefficient (g) between PP molecular chains is reduced. The calculated energy $E_{tau}$ for $delta$ process is in proportion to the shallow traps level, because the shallow traps with a higher level increase the potential barriers of carriers hopping behaviors. The increase in temperature causes the dipole to undergo intense Brownian motion in the electric field, resulting in a decrease in $Deltavarepsilon_{a}$ with increasing temperature. The thermal motion of the charge increases the mobility of carriers in the PP and causes $Deltavarepsilon_{delta}$ to increasewith increasingtemperature.","PeriodicalId":6795,"journal":{"name":"2020 IEEE 3rd International Conference on Dielectrics (ICD)","volume":"43 1","pages":"431-434"},"PeriodicalIF":0.0,"publicationDate":"2020-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86911218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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