Pub Date : 2019-06-01DOI: 10.1109/EIC43217.2019.9046607
Cong Liu, J. Hao, Runhao Zou, Zhiwei Li
Power transformers are the key equipment of power transmission and distribution system. Therefore, it is necessary to study the influence of different fault types on the temperature distribution of transformer windings. Based on the real converter winding model, a fast solution method is proposed to obtain the temperature and velocity distribution of the winding. And the typical winding faults are analyzed. Oil duct flow velocity in the maximum oil baffle plate, the flow of the oil take away heat, makes the temperature rise between regions is about 6–8 K. Hot spot temperature of the winding is located at 184 the layers (92% of the height) and is 67.3 °C. With the decrease of oil flow velocity, the increase of the overall winding temperature and the overheating of the end area as a whole. Oil change for little effects on the overall temperature of the winding, but the wire under the narrowed oil channel generated local overheating and became a new hot spot. This paper provides a preliminary exploration for the development of transformer thermal faults.
{"title":"Influence of Oil Duct Variation on Thermal Characteristics of Converter Transformer Winding","authors":"Cong Liu, J. Hao, Runhao Zou, Zhiwei Li","doi":"10.1109/EIC43217.2019.9046607","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046607","url":null,"abstract":"Power transformers are the key equipment of power transmission and distribution system. Therefore, it is necessary to study the influence of different fault types on the temperature distribution of transformer windings. Based on the real converter winding model, a fast solution method is proposed to obtain the temperature and velocity distribution of the winding. And the typical winding faults are analyzed. Oil duct flow velocity in the maximum oil baffle plate, the flow of the oil take away heat, makes the temperature rise between regions is about 6–8 K. Hot spot temperature of the winding is located at 184 the layers (92% of the height) and is 67.3 °C. With the decrease of oil flow velocity, the increase of the overall winding temperature and the overheating of the end area as a whole. Oil change for little effects on the overall temperature of the winding, but the wire under the narrowed oil channel generated local overheating and became a new hot spot. This paper provides a preliminary exploration for the development of transformer thermal faults.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126155814","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046587
G. Montanari, R. Hebner, P. Seri, R. Ghosh
Partial discharge (PD) detection is a fundamental test for the design and diagnosis of insulation systems, particularly organic materials which must operate throughout their whole life without PD. The measurement of Partial Discharge Inception Voltage (PDIV) and Repetitive Partial Discharge Inception Voltage (RPDIV), the latter defined for power electronic-type supply, is therefore a key issue for the design and qualification tests of Type I insulation system of rotating machines fed by power converters. While experience and technology for PD inception measurements under sinusoidal voltage supply is well established, the same does not hold under repetitive-pulse voltage waveforms, such as those provided by inverters. In addition, electromagnetic noise generated by electronic switch commutation can overlap with PD pulses signals and this is even more cumbersome when fast rise-time components are employed, such as GaN or SiC semiconductors. Moreover, this is also the condition which is the most stressful for stator wire insulation. This work investigates methods to detect PD pulses on enameled wires, rejecting noise efficiently, under repetitive impulsive voltages with different rise times, from 60 ns to 1000 ns. The proposed techniques can be implemented to achieve un-supervised noise rejection, which would be an important goal for both off-line and on-line PD testing.
{"title":"Noise rejection and partial discharge identification in PDIV tests of insulated wires under repetitive impulse supply voltage","authors":"G. Montanari, R. Hebner, P. Seri, R. Ghosh","doi":"10.1109/EIC43217.2019.9046587","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046587","url":null,"abstract":"Partial discharge (PD) detection is a fundamental test for the design and diagnosis of insulation systems, particularly organic materials which must operate throughout their whole life without PD. The measurement of Partial Discharge Inception Voltage (PDIV) and Repetitive Partial Discharge Inception Voltage (RPDIV), the latter defined for power electronic-type supply, is therefore a key issue for the design and qualification tests of Type I insulation system of rotating machines fed by power converters. While experience and technology for PD inception measurements under sinusoidal voltage supply is well established, the same does not hold under repetitive-pulse voltage waveforms, such as those provided by inverters. In addition, electromagnetic noise generated by electronic switch commutation can overlap with PD pulses signals and this is even more cumbersome when fast rise-time components are employed, such as GaN or SiC semiconductors. Moreover, this is also the condition which is the most stressful for stator wire insulation. This work investigates methods to detect PD pulses on enameled wires, rejecting noise efficiently, under repetitive impulsive voltages with different rise times, from 60 ns to 1000 ns. The proposed techniques can be implemented to achieve un-supervised noise rejection, which would be an important goal for both off-line and on-line PD testing.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125845869","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046626
A. Cimino, F. Jenau, A. Mashkin, D. Behnisch, R. Merte, H. Steins, F. Pohlmann
This paper investigates the influence of electrical, thermal and in particular mechanical stress on the electrical insulation system of generator stator bars. For this purpose, accelerated ageing tests are performed in order to analyze the ageing behavior with experimental results. As the focus is on mechanically dominated ageing, there is a defined variation of the mechanical load. Previously, studies have been performed on alternating stress, which is fully reserved. In this work the unidirectional stress is investigated.
{"title":"Unidirectional Accelerated Lifetime Investigations of Mechanically Dominated Aged Electrical Insulation System used in Generator Winding Bars","authors":"A. Cimino, F. Jenau, A. Mashkin, D. Behnisch, R. Merte, H. Steins, F. Pohlmann","doi":"10.1109/EIC43217.2019.9046626","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046626","url":null,"abstract":"This paper investigates the influence of electrical, thermal and in particular mechanical stress on the electrical insulation system of generator stator bars. For this purpose, accelerated ageing tests are performed in order to analyze the ageing behavior with experimental results. As the focus is on mechanically dominated ageing, there is a defined variation of the mechanical load. Previously, studies have been performed on alternating stress, which is fully reserved. In this work the unidirectional stress is investigated.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128924326","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046551
A. Caprara, G. Ciotti, A. Cavallini, A. Rumi
This paper investigates the behavior of the Repetitive Partial Discharge Inception Voltage (RPDIV), which is defined as the voltage level at which at least one PD occurs in two voltage impulses (or at least five in ten - according to the Standard in use). It has been noted that, increasing by steps the voltage value above the PDIV level, sporadic bursts of PD occur. During the bursts, the conditions for RPDIV are met, but the PD activity is unstable and may well extinguish. Since the definition of RPDIV in the International Standards does not consider PD bursts, the results of RPDIV using different measurement systems might vary depending on how the RPDIV is calculated, affecting the overall comparability of the results. In the test reported here, it came out that conditioning the system above PDIV might be a suitable way to reduce the probability of observing PD bursts. By combining the behavior of PD activity and the impact of conditioning, suggestions to perform more accurate measurements are eventually derived.
{"title":"The RPDIV and the limits of its definition according to IEC 60034-18-41: the effect of voltage conditioning","authors":"A. Caprara, G. Ciotti, A. Cavallini, A. Rumi","doi":"10.1109/EIC43217.2019.9046551","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046551","url":null,"abstract":"This paper investigates the behavior of the Repetitive Partial Discharge Inception Voltage (RPDIV), which is defined as the voltage level at which at least one PD occurs in two voltage impulses (or at least five in ten - according to the Standard in use). It has been noted that, increasing by steps the voltage value above the PDIV level, sporadic bursts of PD occur. During the bursts, the conditions for RPDIV are met, but the PD activity is unstable and may well extinguish. Since the definition of RPDIV in the International Standards does not consider PD bursts, the results of RPDIV using different measurement systems might vary depending on how the RPDIV is calculated, affecting the overall comparability of the results. In the test reported here, it came out that conditioning the system above PDIV might be a suitable way to reduce the probability of observing PD bursts. By combining the behavior of PD activity and the impact of conditioning, suggestions to perform more accurate measurements are eventually derived.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125794758","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046558
P. Collin, D. Malec, Y. Lefèvre
In the literature, the Paschen's criterion is widely used to determine partial discharges (PD) inception in the electrical insulation systems (EIS) of machines. This criterion has been established for 2 metallic plane electrodes facing each other in a uniform electric field. The objective of this communication is to determine whether Paschen's criterion may still be used in a configuration of enameled round wires in non-uniform field. For that purpose, PD risk between 2 parallel enameled round wires at atmospheric pressure has been studied, from both measurements and simulation points of view. Different experiments with different samples geometry, fully measured by a digital microscope, has been compared to simulation using Paschen's criterion. This work aims to bring out a more complete criterion on PD detection, in the case of enameled round wires, in order to use it as a reference in a software under development. This software will help designers to take into account the PD phenomena in the design stage of the EIS of a low voltage rotating machine fed by an inverter.
{"title":"About the relevance of using Paschen's criterion for partial discharges inception voltage (PDIV) estimation when designing the electrical insulation system of inverter fed motors","authors":"P. Collin, D. Malec, Y. Lefèvre","doi":"10.1109/EIC43217.2019.9046558","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046558","url":null,"abstract":"In the literature, the Paschen's criterion is widely used to determine partial discharges (PD) inception in the electrical insulation systems (EIS) of machines. This criterion has been established for 2 metallic plane electrodes facing each other in a uniform electric field. The objective of this communication is to determine whether Paschen's criterion may still be used in a configuration of enameled round wires in non-uniform field. For that purpose, PD risk between 2 parallel enameled round wires at atmospheric pressure has been studied, from both measurements and simulation points of view. Different experiments with different samples geometry, fully measured by a digital microscope, has been compared to simulation using Paschen's criterion. This work aims to bring out a more complete criterion on PD detection, in the case of enameled round wires, in order to use it as a reference in a software under development. This software will help designers to take into account the PD phenomena in the design stage of the EIS of a low voltage rotating machine fed by an inverter.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129902286","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046617
Robert C. Breazeal, A. Sbravati, D. Robalino
Despite the efforts of the utilities to designate properly sized transformers for the distribution network, transformers are routinely subjected to significant overloads during peak hours. This is especially common during hot summer days where the hot spot temperature value may exceed the design limits. With the utilization of natural ester liquid in distribution transformers, the rate of paper degradation is expected to be reduced in comparison to a traditional mineral oil unit at same conditions. The acceptable top oil temperature for natural ester is significantly higher than that for mineral oil. The improvements for both solid and liquid insulation enhance the ability to subject the distribution transformer to overload conditions. An experimental protocol was performed in 2017 to further investigate these properties of natural ester oil. In this document, the research work performed by Southern California Edison (SCE) is summarized and described in detail. For a period of one year, 11 transformers were subjected to thermal overload and thus, to an accelerated aging process. Transformers were loaded for cycles of 4 weeks, up to 145% of nameplate rating. After each loading cycle the transformers were cooled down to ambient temperature and tested using dielectric frequency response to document and trend the changes in the dielectric conditions of the complex insulation system. Challenges, lessons learned and recommendations are discussed herein.
{"title":"Evaluation of Natural Ester Retrofilled Transformers After One Year of Continuous Overload","authors":"Robert C. Breazeal, A. Sbravati, D. Robalino","doi":"10.1109/EIC43217.2019.9046617","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046617","url":null,"abstract":"Despite the efforts of the utilities to designate properly sized transformers for the distribution network, transformers are routinely subjected to significant overloads during peak hours. This is especially common during hot summer days where the hot spot temperature value may exceed the design limits. With the utilization of natural ester liquid in distribution transformers, the rate of paper degradation is expected to be reduced in comparison to a traditional mineral oil unit at same conditions. The acceptable top oil temperature for natural ester is significantly higher than that for mineral oil. The improvements for both solid and liquid insulation enhance the ability to subject the distribution transformer to overload conditions. An experimental protocol was performed in 2017 to further investigate these properties of natural ester oil. In this document, the research work performed by Southern California Edison (SCE) is summarized and described in detail. For a period of one year, 11 transformers were subjected to thermal overload and thus, to an accelerated aging process. Transformers were loaded for cycles of 4 weeks, up to 145% of nameplate rating. After each loading cycle the transformers were cooled down to ambient temperature and tested using dielectric frequency response to document and trend the changes in the dielectric conditions of the complex insulation system. Challenges, lessons learned and recommendations are discussed herein.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133104421","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046517
F. Pereira, H. Tatizawa, M. Zanotti
The present work describes how the detection of surface defects located in the slot portion of high-voltage bars (or coils) can be improved with the use of partial discharge (PD) tests. In spite of all care, surface defects capable of damaging the semiconducting slot coating of bars can eventually be created during their manufacturing process or later on, during their installation at site. Although the most commonly used methods to search for surface defects are based upon visual inspections, this work will explore a possible improvement in such methodologies by using electrical methods, such as the acquisition and discrimination of PD pulses. The results shown here represent a first progress report of a larger ongoing project that aims to develop a test method suitable for the quality control of bars and coils mass production. To address the topic in laboratory scale, a series of artificially created defects were produced and systematically tested with different parameters. A number of test conditions was employed to determine under which circumstances the test can be sensitive enough to permit a clear detection and discrimination of the surface damages. It was found that although the mere recording of PD amplitudes is a simpler and straightforward method of detection, it is the analysis of the complete PD patterns that provides the most useful information to identify the defects.
{"title":"Improvements in the Identification of Defects on the Semiconducting Slot Coating of Stator Bars Using Partial Discharges","authors":"F. Pereira, H. Tatizawa, M. Zanotti","doi":"10.1109/EIC43217.2019.9046517","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046517","url":null,"abstract":"The present work describes how the detection of surface defects located in the slot portion of high-voltage bars (or coils) can be improved with the use of partial discharge (PD) tests. In spite of all care, surface defects capable of damaging the semiconducting slot coating of bars can eventually be created during their manufacturing process or later on, during their installation at site. Although the most commonly used methods to search for surface defects are based upon visual inspections, this work will explore a possible improvement in such methodologies by using electrical methods, such as the acquisition and discrimination of PD pulses. The results shown here represent a first progress report of a larger ongoing project that aims to develop a test method suitable for the quality control of bars and coils mass production. To address the topic in laboratory scale, a series of artificially created defects were produced and systematically tested with different parameters. A number of test conditions was employed to determine under which circumstances the test can be sensitive enough to permit a clear detection and discrimination of the surface damages. It was found that although the mere recording of PD amplitudes is a simpler and straightforward method of detection, it is the analysis of the complete PD patterns that provides the most useful information to identify the defects.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132930123","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046589
Yifan Zhou, Wei Wang, T. Guo, Jiale Qi
The accumulation effect of space charge in high voltage direct current (HVDC) cable may lead to the distortion of internal electric field, accelerate insulation aging and even cause insulation breakdown, which seriously affected the reliability of operation of HVDC cable. With the operation of HVDC cable, the radial distribution of temperature gradient is developed within the insulation material among the temperature presented high on internal layer and low on external layer. However, as the existence of non-linear phase distortion of the measurement system, cylindrical geometric structure for HVDC cable and temperature gradient, the measured waveforms of space charge in HVDC cable based on pulsed electro-acoustic (PEA) method induces distortion. In this paper, the temperature at cable core is set at 30°C, 60°C and 90°C respectively in order to form different temperature gradients, the negative DC electric Field of 10 kV/mm is applied to HVDC cable, space charge distribution characteristics are researched based on the space charge measurement system using PEA method for HVDC cable, the measured waveforms developed by our laboratory can be corrected by modified recovery algorithms. It is concluded that with the increase of temperature at cable core, heterocharges gradually accumulate near the lower temperature side of HVDC cable. The higher temperature at cable core can also promote the injection of homocharges in HVDC cable. The temperature gradient in HVDC cable has importance impact on space charge accumulation, the research on space charge distribution characteristics can provide basis for further study on space charge behavior mechanism under temperature gradient.
{"title":"Measurement of Space Charge Distribution Characteristics in the Actual HVDC Cable","authors":"Yifan Zhou, Wei Wang, T. Guo, Jiale Qi","doi":"10.1109/EIC43217.2019.9046589","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046589","url":null,"abstract":"The accumulation effect of space charge in high voltage direct current (HVDC) cable may lead to the distortion of internal electric field, accelerate insulation aging and even cause insulation breakdown, which seriously affected the reliability of operation of HVDC cable. With the operation of HVDC cable, the radial distribution of temperature gradient is developed within the insulation material among the temperature presented high on internal layer and low on external layer. However, as the existence of non-linear phase distortion of the measurement system, cylindrical geometric structure for HVDC cable and temperature gradient, the measured waveforms of space charge in HVDC cable based on pulsed electro-acoustic (PEA) method induces distortion. In this paper, the temperature at cable core is set at 30°C, 60°C and 90°C respectively in order to form different temperature gradients, the negative DC electric Field of 10 kV/mm is applied to HVDC cable, space charge distribution characteristics are researched based on the space charge measurement system using PEA method for HVDC cable, the measured waveforms developed by our laboratory can be corrected by modified recovery algorithms. It is concluded that with the increase of temperature at cable core, heterocharges gradually accumulate near the lower temperature side of HVDC cable. The higher temperature at cable core can also promote the injection of homocharges in HVDC cable. The temperature gradient in HVDC cable has importance impact on space charge accumulation, the research on space charge distribution characteristics can provide basis for further study on space charge behavior mechanism under temperature gradient.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134025244","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046519
G. Komiya, T. Imai, Y. Miyauchi
Since SF6 gas used as an insulating medium for switchgear is a greenhouse gas, its use needs to be reduced. Toshiba Corporation has developed solid insulated switchgear (SIS) in which the main circuit is molded with an epoxy composite. Since developing the 24 kV class SIS in 2002, a 72/84 kV class SIS has been launched. The high dielectric strength of the epoxy composites enables these solid insulation systems to provide compact equipment. However, it is necessary to consider the problem of heat radiation in SIS, as epoxy composite has low thermal conductivity. Therefore, development of high thermal conductivity epoxy composites has been desired for large current class SIS. In this study, we focus on magnesium oxide (MgO), which has a thermal conductivity having low-cost. The developed epoxy composite was filled with MgO having high thermal conductivity and SiO2 having a low coefficient of thermal expansion. By using the estimation equations of thermal conductivity and coefficient of thermal expansion, we could efficiently determine the formulation of the high thermal conductivity epoxy composite. The thermal conductivity of the developed material was 1.39 W/(m·K), which is equivalent to 2.5 times that of conventional material. In addition, other characteristics also showed excellent values, such as 23×10-6/K of the coefficient of thermal expansion and 2,513 mPa.s of viscosity. These values satisfied the required ones for large current SIS. Thermal analysis revealed that applying the high thermal conductivity epoxy composite to 2500 A SIS can reduce the temperature rise by about 10 K. By applying the high thermal conductivity epoxy composite, we are convinced that a large current of SIS with merits such as low maintenance and compactness will be realized.
由于SF6气体作为开关设备的绝缘介质是一种温室气体，因此需要减少其使用。东芝公司开发了固体绝缘开关设备(SIS)，其中主电路用环氧复合材料成型。自2002年开发24千伏级SIS以来，已经推出了72/84千伏级SIS。环氧复合材料的高介电强度使这些固体绝缘系统能够提供紧凑的设备。但是，由于环氧复合材料导热系数低，在SIS中需要考虑热辐射问题。因此，开发高导热环氧复合材料已成为大电流级SIS的迫切需要。在这项研究中，我们重点研究了氧化镁(MgO)，它具有低成本的导热性。制备的环氧复合材料以导热系数高的MgO和热膨胀系数低的SiO2填充。利用导热系数和热膨胀系数估算方程，可以有效地确定高导热环氧复合材料的配方。该材料的导热系数为1.39 W/(m·K)，相当于传统材料的2.5倍。此外，热膨胀系数23×10-6/K和2513 mPa等其他特性也表现出优异的数值。粘度S。这些值满足大电流SIS的要求。热分析表明，将高导热环氧复合材料应用于2500 A SIS，可使温升降低约10 K。通过应用高导热环氧复合材料，我们相信将实现具有低维护和紧凑等优点的大电流SIS。
{"title":"Development of High Thermal Conductivity Epoxy Composite for Large Current Switchgear","authors":"G. Komiya, T. Imai, Y. Miyauchi","doi":"10.1109/EIC43217.2019.9046519","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046519","url":null,"abstract":"Since SF6 gas used as an insulating medium for switchgear is a greenhouse gas, its use needs to be reduced. Toshiba Corporation has developed solid insulated switchgear (SIS) in which the main circuit is molded with an epoxy composite. Since developing the 24 kV class SIS in 2002, a 72/84 kV class SIS has been launched. The high dielectric strength of the epoxy composites enables these solid insulation systems to provide compact equipment. However, it is necessary to consider the problem of heat radiation in SIS, as epoxy composite has low thermal conductivity. Therefore, development of high thermal conductivity epoxy composites has been desired for large current class SIS. In this study, we focus on magnesium oxide (MgO), which has a thermal conductivity having low-cost. The developed epoxy composite was filled with MgO having high thermal conductivity and SiO2 having a low coefficient of thermal expansion. By using the estimation equations of thermal conductivity and coefficient of thermal expansion, we could efficiently determine the formulation of the high thermal conductivity epoxy composite. The thermal conductivity of the developed material was 1.39 W/(m·K), which is equivalent to 2.5 times that of conventional material. In addition, other characteristics also showed excellent values, such as 23×10-6/K of the coefficient of thermal expansion and 2,513 mPa.s of viscosity. These values satisfied the required ones for large current SIS. Thermal analysis revealed that applying the high thermal conductivity epoxy composite to 2500 A SIS can reduce the temperature rise by about 10 K. By applying the high thermal conductivity epoxy composite, we are convinced that a large current of SIS with merits such as low maintenance and compactness will be realized.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126513860","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 : 2019-06-01DOI: 10.1109/EIC43217.2019.9046557
R. Soltani, Pascalina Gaillardetz, I. Chichkin, Bruce Ledger
Partial discharge (PD) is a well-known indicator of an aging insulation system, so trending the PD activity is suggested as a tool to prevent insulation failures by targeted interventions. This paper presents a case study in which on-line PD measurements showed a significant increase over several years and triggered an investigation and repair plan. Off-line site tests confirmed the concerns and helped in locating and replacing the most vulnerable bars. Laboratory tests on the service-aged bars also provided valuable information about the root cause and insulation condition of the winding.
{"title":"Investigation of Partial Discharge Activity and Insulation Life of a Large Hydro Generator","authors":"R. Soltani, Pascalina Gaillardetz, I. Chichkin, Bruce Ledger","doi":"10.1109/EIC43217.2019.9046557","DOIUrl":"https://doi.org/10.1109/EIC43217.2019.9046557","url":null,"abstract":"Partial discharge (PD) is a well-known indicator of an aging insulation system, so trending the PD activity is suggested as a tool to prevent insulation failures by targeted interventions. This paper presents a case study in which on-line PD measurements showed a significant increase over several years and triggered an investigation and repair plan. Off-line site tests confirmed the concerns and helped in locating and replacing the most vulnerable bars. Laboratory tests on the service-aged bars also provided valuable information about the root cause and insulation condition of the winding.","PeriodicalId":340602,"journal":{"name":"2019 IEEE Electrical Insulation Conference (EIC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130037301","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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