Pub Date : 2019-06-23DOI: 10.1109/ICDL.2019.8796707
Jens-Michael Löwe, V. Hinrichsen
High voltage insulators in electric power transmission and distribution must withstand extreme weather conditions like rain or snow without long-term degradation. An increasing amount of outdoor composite insulators uses silicone rubber due to the various advantages over glass and ceramic. One difficulty is the presence of water droplets residing on the hydrophobic silicone rubber surface of insulators, which locally alter the electric field. Specifically, the electric field is strongly enhanced at the three phase contact line, which can lead to electrical partial discharges and affect the aging of the insulator’s surface. The present contribution investigates the behavior of sessile water droplets exposed to strong electric fields with a high-speed camera. Electrically charged and uncharged droplets are generated under well-defined conditions and placed on a generic insulator model. The oscillation frequency of the droplet in resonance mode is investigated in detail with respect to the amount of charge, droplet volume, frequency of the electric field as well as the electric field strength. Significant changes in drop behavior are observed depending on the charge and the electric field strength. A regime map based on the experimental data as well as a mathematical model is developed to quantity the necessary conditions for the change of behavior. The performed experiments improve the understanding of droplets in electric fields as well as the ageing process of high voltage insulators.
{"title":"Experimental Investigation of the Influence of Electric Charge on the Behavior of Water Droplets in Electric Fields","authors":"Jens-Michael Löwe, V. Hinrichsen","doi":"10.1109/ICDL.2019.8796707","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796707","url":null,"abstract":"High voltage insulators in electric power transmission and distribution must withstand extreme weather conditions like rain or snow without long-term degradation. An increasing amount of outdoor composite insulators uses silicone rubber due to the various advantages over glass and ceramic. One difficulty is the presence of water droplets residing on the hydrophobic silicone rubber surface of insulators, which locally alter the electric field. Specifically, the electric field is strongly enhanced at the three phase contact line, which can lead to electrical partial discharges and affect the aging of the insulator’s surface. The present contribution investigates the behavior of sessile water droplets exposed to strong electric fields with a high-speed camera. Electrically charged and uncharged droplets are generated under well-defined conditions and placed on a generic insulator model. The oscillation frequency of the droplet in resonance mode is investigated in detail with respect to the amount of charge, droplet volume, frequency of the electric field as well as the electric field strength. Significant changes in drop behavior are observed depending on the charge and the electric field strength. A regime map based on the experimental data as well as a mathematical model is developed to quantity the necessary conditions for the change of behavior. The performed experiments improve the understanding of droplets in electric fields as well as the ageing process of high voltage insulators.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123514596","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796652
P. Traoré, C. Louste, U. Seth, P. Vázquez, J. Yagoobi
This study aims to demonstrate the capability of simulating the flow induced by the dissociation of neutral molecules in a weakly conductive liquid in a full 3D channel. We investigate numerically the EHD pumping through pure conduction phenomenon in a 3D rectangular channel. It is important to verify if the assumptions allowing us to consider that the flow remains 2D are always valid and in which circumstances some 3D phenomena may occur? Not very surprisingly it is observed that while increasing the electric Reynolds number in increasing the electric potential difference between the two electrodes makes the flow becoming turbulent. In such situation 2D computations are not anymore valid.
{"title":"Numerical investigation of EHD pumping through conduction phenomenon in a rectangular channel.","authors":"P. Traoré, C. Louste, U. Seth, P. Vázquez, J. Yagoobi","doi":"10.1109/ICDL.2019.8796652","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796652","url":null,"abstract":"This study aims to demonstrate the capability of simulating the flow induced by the dissociation of neutral molecules in a weakly conductive liquid in a full 3D channel. We investigate numerically the EHD pumping through pure conduction phenomenon in a 3D rectangular channel. It is important to verify if the assumptions allowing us to consider that the flow remains 2D are always valid and in which circumstances some 3D phenomena may occur? Not very surprisingly it is observed that while increasing the electric Reynolds number in increasing the electric potential difference between the two electrodes makes the flow becoming turbulent. In such situation 2D computations are not anymore valid.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122920223","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796685
S. Elia, A. Ruvio, Damiano Bracci
The paper focuses on the reliability of an undervoltage electromechanical relay suitable for critical industrial applications. The specific application underlined in this paper is a mutual aid system for gensets: the relay is able to actuate the parallel of the batteries in case of failure of the starting-up of the genset. A particular “Plunger-type” electromechanical device, with redundant contacts, has been proposed in order to maximize the MTBF parameter; electronics devices have been rejected in according with on-filed statistic surveys about the relative failure rates. The relay is equipped with a natural ester oil delaying system (dashpot): physical and dielectric characteristics of natural ester oil can assure better delaying system performances and insulating level. Other advantages obtainable by using insulating ester oil into the relay are also highlighted.
{"title":"A study on a high-reliability electromechanical undervoltage relay immersed in natural ester oil: application in mutual aid system for gensets using","authors":"S. Elia, A. Ruvio, Damiano Bracci","doi":"10.1109/ICDL.2019.8796685","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796685","url":null,"abstract":"The paper focuses on the reliability of an undervoltage electromechanical relay suitable for critical industrial applications. The specific application underlined in this paper is a mutual aid system for gensets: the relay is able to actuate the parallel of the batteries in case of failure of the starting-up of the genset. A particular “Plunger-type” electromechanical device, with redundant contacts, has been proposed in order to maximize the MTBF parameter; electronics devices have been rejected in according with on-filed statistic surveys about the relative failure rates. The relay is equipped with a natural ester oil delaying system (dashpot): physical and dielectric characteristics of natural ester oil can assure better delaying system performances and insulating level. Other advantages obtainable by using insulating ester oil into the relay are also highlighted.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121892225","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796723
S. Fink, V. Zwecker
The dielectric strength of liquid nitrogen is an important design issue for numerous cryogenic high voltage apparatus. In some cases the design must consider gas bubble occurrence caused by resistive heating, e.g. during activation of a resistive superconducting fault current limiter. The objective of the FASTGRID project is to support a liquid nitrogen cooled superconducting fault current limiter solution for DC grids. The high voltage test facility Fatelini 2 allows DC testing of liquid nitrogen up to voltages of 325 kV. A high voltage electrode with the shape similar to a bell and a ground plane electrode were used. A heater was installed within the ground plate in order to allow bubble generation which was verified via video observation. A one hour voltage stress was performed as an initial voltage step without activation of the heater. The test was continued with a duration of 15 min with the same voltage but including five 500 W heating impulses of 10 s duration, each. In case of no breakdown the test was followed by about 10% voltage increases for subsequent steps of 15 min DC operation including 5 heating impulses, each. The maximum examined gap length was 96 mm for negative polarity only. In most cases the breakdown occurred during bubble generation. An outliner with a very low disturbed voltage waveform did also occur. The breakdown voltage values obtained by these tests are lower than for test series which were performed without operation of the heater.
{"title":"15 Min Dc breakdown tests with liquid nitrogen","authors":"S. Fink, V. Zwecker","doi":"10.1109/ICDL.2019.8796723","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796723","url":null,"abstract":"The dielectric strength of liquid nitrogen is an important design issue for numerous cryogenic high voltage apparatus. In some cases the design must consider gas bubble occurrence caused by resistive heating, e.g. during activation of a resistive superconducting fault current limiter. The objective of the FASTGRID project is to support a liquid nitrogen cooled superconducting fault current limiter solution for DC grids. The high voltage test facility Fatelini 2 allows DC testing of liquid nitrogen up to voltages of 325 kV. A high voltage electrode with the shape similar to a bell and a ground plane electrode were used. A heater was installed within the ground plate in order to allow bubble generation which was verified via video observation. A one hour voltage stress was performed as an initial voltage step without activation of the heater. The test was continued with a duration of 15 min with the same voltage but including five 500 W heating impulses of 10 s duration, each. In case of no breakdown the test was followed by about 10% voltage increases for subsequent steps of 15 min DC operation including 5 heating impulses, each. The maximum examined gap length was 96 mm for negative polarity only. In most cases the breakdown occurred during bubble generation. An outliner with a very low disturbed voltage waveform did also occur. The breakdown voltage values obtained by these tests are lower than for test series which were performed without operation of the heater.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132149051","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796544
M. Becerra, M. Aljure, J. Nilsson
The evaluation of the high-field generation and loss of charged carriers is a key step to simulate any prebreakdown process in a dielectric liquid. Currently, the electron generation in mineral oil has been widely described in terms of “electric-field-dependent molecular ionization” and the electron loss is estimated using a fixed attachment time constant. This paper reports our next step towards the quantitative characterization of the production and loss of electrons in mineral oil. In this step, the electrical conduction measurements are performed in mineral oil for a needle-plane configuration (tip radius ~3 μm) and submicrometric gap distances (ranging between 10 to 100 μm). Conduction currents in negative polarity are reported from 10-12 to 10-7A, from the ohmic to the space-charge limited regimes. In order to check the validity of existing simulation models for mineral oil, computer simulation is used to calculate the VI characteristic in the liquid considering electrohydrodynamic (EHD) motion. It is shown that the active zone where electrons are produced in front of the needle is around 10 μm long. Furthermore, it is found that electrons travel a similar distance before they attach into ions. It is also shown that the currents are grossly misestimated when parameters proposed in the literature to model generation and loss of electrons in mineral oil are used.
{"title":"Assessing the Production and Loss of Electrons from Conduction Currents in Mineral Oil","authors":"M. Becerra, M. Aljure, J. Nilsson","doi":"10.1109/ICDL.2019.8796544","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796544","url":null,"abstract":"The evaluation of the high-field generation and loss of charged carriers is a key step to simulate any prebreakdown process in a dielectric liquid. Currently, the electron generation in mineral oil has been widely described in terms of “electric-field-dependent molecular ionization” and the electron loss is estimated using a fixed attachment time constant. This paper reports our next step towards the quantitative characterization of the production and loss of electrons in mineral oil. In this step, the electrical conduction measurements are performed in mineral oil for a needle-plane configuration (tip radius ~3 μm) and submicrometric gap distances (ranging between 10 to 100 μm). Conduction currents in negative polarity are reported from 10-12 to 10-7A, from the ohmic to the space-charge limited regimes. In order to check the validity of existing simulation models for mineral oil, computer simulation is used to calculate the VI characteristic in the liquid considering electrohydrodynamic (EHD) motion. It is shown that the active zone where electrons are produced in front of the needle is around 10 μm long. Furthermore, it is found that electrons travel a similar distance before they attach into ions. It is also shown that the currents are grossly misestimated when parameters proposed in the literature to model generation and loss of electrons in mineral oil are used.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121333642","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796829
A. Beroual
This paper is a synthesis of acquired results by my group on creeping discharges at fluid/solid interfaces during the last two decades. It aims to evidence the analogies between the characteristic parameters of surface discharges propagating on liquid/solid and gas/solid interfaces (namely, shape, stopping length, current/electrical charge, fractal dimension) and the dependency of these characteristics on the same physical parameters. It also evidences the influence of the capacitive effects on these characteristics under different types of voltage waveforms namely AC, DC and lightning impulse voltages.
{"title":"Creeping Discharges at Liquid/solid and Gas/Solid Interfaces: Analogies and Involving Mechanisms","authors":"A. Beroual","doi":"10.1109/ICDL.2019.8796829","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796829","url":null,"abstract":"This paper is a synthesis of acquired results by my group on creeping discharges at fluid/solid interfaces during the last two decades. It aims to evidence the analogies between the characteristic parameters of surface discharges propagating on liquid/solid and gas/solid interfaces (namely, shape, stopping length, current/electrical charge, fractal dimension) and the dependency of these characteristics on the same physical parameters. It also evidences the influence of the capacitive effects on these characteristics under different types of voltage waveforms namely AC, DC and lightning impulse voltages.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126959955","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796759
F. Scatiggio, F. Pepe, Simone Sacco, C. Serafino
Mineral-base oil has been the main insulating liquid for filling power transformers since the 1900’s due to its ready worldwide availability, low cost and good properties. Anyway, in recent times the new desires for a safer non-flammable, an environmental acceptable and a less impacting on sustainable common resources fluid has driven many users in the research and use of alternative fluids to mineral oil. Despite the availability of other fluids, the synthetic and natural (from vegetable seeds) esters (NE) represent the major alternative to mineral insulating oils. Terna as Italian Transmission System Operator (TSO) in according to European Union Directive 2001/42/EC should aim at guaranteeing high levels of environmental protection and safety, so Terna is also aware of its responsibility towards the community and has translated this into a single strategy: to find the right balance between the country’s energy needs, nature conservation and the safeguarding of Italy’s cultural heritage. In addition to the environmental and fire safety benefits, the review of the possible advantages of natural ester-filled transformers allowed identifying alternative design criteria with relevant financial benefits. The TERNA goal was to increase the loading ability of their transformers, mainly by enhancing a much higher limit for overloading in comparison to traditional transformers. For this prototype TERNA selected a 400/135 kV 250 MVA autotransformer, a standard practice for their network. To explore the superior thermal class of the new insulation system, the transformer manufacturer confirmed the possibility of designing this transformer with a “permanent additional capacity”. Five autotransformers with NE are already in service and in its next-2-years strategic plan Terna has planned the installation of more than 20 new power autotransformers filled with natural ester
{"title":"Increased Loadability of Transformers Immersed in Natural Ester","authors":"F. Scatiggio, F. Pepe, Simone Sacco, C. Serafino","doi":"10.1109/ICDL.2019.8796759","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796759","url":null,"abstract":"Mineral-base oil has been the main insulating liquid for filling power transformers since the 1900’s due to its ready worldwide availability, low cost and good properties. Anyway, in recent times the new desires for a safer non-flammable, an environmental acceptable and a less impacting on sustainable common resources fluid has driven many users in the research and use of alternative fluids to mineral oil. Despite the availability of other fluids, the synthetic and natural (from vegetable seeds) esters (NE) represent the major alternative to mineral insulating oils. Terna as Italian Transmission System Operator (TSO) in according to European Union Directive 2001/42/EC should aim at guaranteeing high levels of environmental protection and safety, so Terna is also aware of its responsibility towards the community and has translated this into a single strategy: to find the right balance between the country’s energy needs, nature conservation and the safeguarding of Italy’s cultural heritage. In addition to the environmental and fire safety benefits, the review of the possible advantages of natural ester-filled transformers allowed identifying alternative design criteria with relevant financial benefits. The TERNA goal was to increase the loading ability of their transformers, mainly by enhancing a much higher limit for overloading in comparison to traditional transformers. For this prototype TERNA selected a 400/135 kV 250 MVA autotransformer, a standard practice for their network. To explore the superior thermal class of the new insulation system, the transformer manufacturer confirmed the possibility of designing this transformer with a “permanent additional capacity”. Five autotransformers with NE are already in service and in its next-2-years strategic plan Terna has planned the installation of more than 20 new power autotransformers filled with natural ester","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131534380","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796845
Michelle Nassar, N. Chauris, P. Traoré, J. Yagoobi, Anny Michel, M. Daaboul, C. Louste
Nowadays, heat transfer enhancement devices are becoming very essential in many applications. Most of electronic devices, from the simplest to the most sophisticated, contain processors. Advanced processors require efficient cooling for an optimal performance. Due to the growing interest in faster and lighter devices, researchers always seek to innovate and optimize cooling strategies. In spatial applications, the use of typical cooling systems can cause complications due to the vibrations during takeoff and due to zero gravity effects. Electrohydrodynamic (EHD) pumping, which is based on the interaction of a dielectric liquid with an electric field, could present a solution to all these challenges. EHD pumps were considered a breakthrough in the field of cooling since they demonstrate many advantages over other types of pumps. EHD devices are less power consuming, lighter and cheaper. They don’t have moving parts and they are suitable for microgravity applications. The hydrofluoroethers (HFE) are dielectric liquids that could be ideally utilized in these pumps for many applications. Being dielectric fluids with eco-friendly properties, HFEs could replace CFCs, HFCs, HCFCs, and PFCs. Due to their promising EHD applications, studies must be done to investigate the variation of their dielectric behavior with electric field and with temperature. This work presents an experimental investigation of the dielectric characteristics of HFE-7000 with temperature variations. Understanding this aspect can help enhance and optimize the performance of EHD systems.
{"title":"Study of the Dielectric Behavior of HFE-7000 in function of Electric Field and Temperature Variations","authors":"Michelle Nassar, N. Chauris, P. Traoré, J. Yagoobi, Anny Michel, M. Daaboul, C. Louste","doi":"10.1109/ICDL.2019.8796845","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796845","url":null,"abstract":"Nowadays, heat transfer enhancement devices are becoming very essential in many applications. Most of electronic devices, from the simplest to the most sophisticated, contain processors. Advanced processors require efficient cooling for an optimal performance. Due to the growing interest in faster and lighter devices, researchers always seek to innovate and optimize cooling strategies. In spatial applications, the use of typical cooling systems can cause complications due to the vibrations during takeoff and due to zero gravity effects. Electrohydrodynamic (EHD) pumping, which is based on the interaction of a dielectric liquid with an electric field, could present a solution to all these challenges. EHD pumps were considered a breakthrough in the field of cooling since they demonstrate many advantages over other types of pumps. EHD devices are less power consuming, lighter and cheaper. They don’t have moving parts and they are suitable for microgravity applications. The hydrofluoroethers (HFE) are dielectric liquids that could be ideally utilized in these pumps for many applications. Being dielectric fluids with eco-friendly properties, HFEs could replace CFCs, HFCs, HCFCs, and PFCs. Due to their promising EHD applications, studies must be done to investigate the variation of their dielectric behavior with electric field and with temperature. This work presents an experimental investigation of the dielectric characteristics of HFE-7000 with temperature variations. Understanding this aspect can help enhance and optimize the performance of EHD systems.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126448916","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796833
Mrutyunjay Maharana, Niharika Baruah, S. K. Nayak, N. Sahoo, M. Chakrobarty
Vegetable oil (VO) based liquid dielectric are gradually being implemented to improve the heat transfer in electrical appliances to enhance their life and improve efficiency. The conventional VO based insulating oil is being moderately researched to improve the understanding of the physical mechanisms involved in their enhanced performance compared to the existing mineral oil (MO) based transformer oil (TO). Despite of all the superior thermophysical and electrical performance of the conventional VO reported in few studies in the context of TO, its vast consumption as edible purpose may limit its application as liquid insulation. Therefore, in this study, a non-conventional VO such as pongamia oil methyl ester (POME) is chosen to be a liquid insulation for transformer. In this paper, the investigation is carried out to evaluate the AC breakdown voltage (ACBDV) of the POME and also the dielectric responses of POME at varying frequency is analyzed at transient condition. POME is extracted from the pongamia crude oil by two step transesterification process followed by refined bleached and deodorization. To understand the comparative enhancement in dielectric integrity, ACBDV analysis of MO and POME is carried out at a line frequency of 50 Hz as per ASTM 1816. The dielectric response such as AC resistivity and relative permittivity of the POME is studied from 50 Hz to 10 MHz. It is observed from the study that the mean BDV of the POME is superior than the MO. Moreover, to detect the probability of failure in ACBDV at different percentage such as 5, 10, 50 and 63.2%, Weibull statistical analysis of the ACBDV is carried for POME and MO. With the rise of frequency from 50 Hz to 10 MHz, the AC resistivity is observed to degrade for both the insulating oils. However, at higher frequency, the resistivity of the POME is not significantly altered and hence making the POME stable in dielectric response at higher frequencies. From the above study, the non-conventional VO and its suitable application in transformer as insulating liquid is a possible option for an efficient insulation.
{"title":"Investigation of AC breakdown strength and frequency varied dielectric response of the non-conventional vegetable oil","authors":"Mrutyunjay Maharana, Niharika Baruah, S. K. Nayak, N. Sahoo, M. Chakrobarty","doi":"10.1109/ICDL.2019.8796833","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796833","url":null,"abstract":"Vegetable oil (VO) based liquid dielectric are gradually being implemented to improve the heat transfer in electrical appliances to enhance their life and improve efficiency. The conventional VO based insulating oil is being moderately researched to improve the understanding of the physical mechanisms involved in their enhanced performance compared to the existing mineral oil (MO) based transformer oil (TO). Despite of all the superior thermophysical and electrical performance of the conventional VO reported in few studies in the context of TO, its vast consumption as edible purpose may limit its application as liquid insulation. Therefore, in this study, a non-conventional VO such as pongamia oil methyl ester (POME) is chosen to be a liquid insulation for transformer. In this paper, the investigation is carried out to evaluate the AC breakdown voltage (ACBDV) of the POME and also the dielectric responses of POME at varying frequency is analyzed at transient condition. POME is extracted from the pongamia crude oil by two step transesterification process followed by refined bleached and deodorization. To understand the comparative enhancement in dielectric integrity, ACBDV analysis of MO and POME is carried out at a line frequency of 50 Hz as per ASTM 1816. The dielectric response such as AC resistivity and relative permittivity of the POME is studied from 50 Hz to 10 MHz. It is observed from the study that the mean BDV of the POME is superior than the MO. Moreover, to detect the probability of failure in ACBDV at different percentage such as 5, 10, 50 and 63.2%, Weibull statistical analysis of the ACBDV is carried for POME and MO. With the rise of frequency from 50 Hz to 10 MHz, the AC resistivity is observed to degrade for both the insulating oils. However, at higher frequency, the resistivity of the POME is not significantly altered and hence making the POME stable in dielectric response at higher frequencies. From the above study, the non-conventional VO and its suitable application in transformer as insulating liquid is a possible option for an efficient insulation.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123041506","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/ICDL.2019.8796513
K. Rapp, Revin Wang, A. Sbravati, R. I. da Silva, V. Tumiatti, M. Pompili
This paper will present natural ester transformer operating data with liquid test results from the units since installation. Various facts and experiences from transformers of two Olympic cities will be shared. The results of physical-chemical and electrical testing including dissolved gas analysis will provide the performance history in the field of a group of power transformers of 138 kV design and of unique designed submersible 10 kV distribution units filled with natural ester fluid, some in service for more than 4 years.
{"title":"Natural ester liquid-filled transformers power the Olympic Games","authors":"K. Rapp, Revin Wang, A. Sbravati, R. I. da Silva, V. Tumiatti, M. Pompili","doi":"10.1109/ICDL.2019.8796513","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796513","url":null,"abstract":"This paper will present natural ester transformer operating data with liquid test results from the units since installation. Various facts and experiences from transformers of two Olympic cities will be shared. The results of physical-chemical and electrical testing including dissolved gas analysis will provide the performance history in the field of a group of power transformers of 138 kV design and of unique designed submersible 10 kV distribution units filled with natural ester fluid, some in service for more than 4 years.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"33 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":"127314694","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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