The Experts below are selected from a list of 564 Experts worldwide ranked by ideXlab platform
Gérard Touchard - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic Hazard in High-Power Transformers: Results of Ten Years of Experience With ${P}^{\prime}$ Capacitive Sensor
IEEE Transactions on Industry Applications, 2013Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain TanguyAbstract:In a high-power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta, dissolved gas measurement, etc. At P' Institute of Poitiers, an original sensor was developed and used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for ten years, this bench has been used to study over a hundred couples of oil/pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards, etc. This paper presents a comparative analysis of these ten years of experience. This analysis provides, among other results, a critical Electrostatic Hazard assessment in transformers and an attempt of discrimination tentative of a suspected transformer.
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Electrostatic Hazard in High Power Transformers: Analyze of Ten Years of the Capacitive Sensor
2012Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain Tanguy, Clamart Cedex FranceAbstract:Abstract-- In high power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta and dissolved gases measurement... At P ' institute of Poitiers an original sensor was developed used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for 10 years, this bench has been used to study over a hundred couples of oil / pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards…. The paper presents a comparative analysis of these 10 years of experience. This analysis provides, among other results, a critical Electrostatic Hazards assessment in transformers and an attempt of discrimination tentative of a suspected transformer Index Terms—Flow electrification, Hazard, power transformer. I
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High Power Transformers Failures due to Flow Electrification: Tools for Understanding the Electrostatic Hazard
2009Co-Authors: Thierry Paillat, J.m. Cabaleiro, M. El-adawy, O. Moreau, Gérard TouchardAbstract:Flow electrification phenomenon is suspected to be responsible for some failures in high power transformers. Acoustic sensor surveys from suspected transformers and visual observations in damaged transformers revealed some evidences of electrical discharges (electric "tree" paths, "worm holes", presence of carbon ...) on inner pressboards. Nevertheless the scenario, which lays the Electrostatic activity and consequently transformer failure, is still not well understood. The goal of this work is to propose some elements for understanding Electrostatic Hazards in high power transformers. Experimental set up has been developed in our laboratory to study flow electrification of oil at a pressboard rectangular duct. As in power transformers, the oil/pressboard couple is insulated from the ground by an oil volume. Pressboard potential, accumulated charges on pressboard surface are recorded and correlated to charge leakage.
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Analysis of flow electrification parameters of power transformer oils
2008 IEEE International Conference on Dielectric Liquids, 2008Co-Authors: R. Vaucelle, Thierry Paillat, J.m. Cabaleiro, O. Moreau, Y. Bertrand, Gérard TouchardAbstract:As a part of a research program at EDF, University of Poitiers has developed a prototype of a sensor dedicated to the monitoring of oil flow electrification through transformer pressboard-made channels. This phenomenon can be responsible for destructive breakdowns when the resulting charge accumulation leads to high electrical fields. In order to identify transformers running Electrostatic Hazards, an experimental setup been has developed to measure the generation and the accumulation on pressboard surface of electric charges with regard to different oil flow conditions (velocity, temperature). Various oils have been characterized with the same reference pressboard: new oils and oils coming from operating transformers (healthy or suspected to develop the phenomenon). The analysis of the measured parameters makes it possible to derive some criteria with regard to the Electrostatic Hazard probability in transformers.
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Flow electrification in power transformers: salt-type additive as a potential remedy?
Journal of Electrostatics, 2005Co-Authors: Audrey Bourgeois, Thierry Paillat, Olivier Moreau, Gérard Mortha, Gérard TouchardAbstract:Flow electrification in power transformers has been studied for the last 30 years, since the charge generation phenomenon was suspected to be responsible for power transformer failures. An experimental set-up has been built at the University of Poitiers in partnership with EDF (French utility) to simulate the oil path along the pressboard between transformer windings. The accumulated charge in a pressboard duct can then be estimated by the integration of the measured capacitive current up to infinite time. Among the investigations to reduce the Electrostatic Hazard, a chemical salt has been injected into new and aged oil at different concentrations. It was found that the accumulated charge was drastically reduced at different salt concentrations for both oils whatever the temperature and the flow rate applied.
Thierry Paillat - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic Hazard in High-Power Transformers: Results of Ten Years of Experience With ${P}^{\prime}$ Capacitive Sensor
IEEE Transactions on Industry Applications, 2013Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain TanguyAbstract:In a high-power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta, dissolved gas measurement, etc. At P' Institute of Poitiers, an original sensor was developed and used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for ten years, this bench has been used to study over a hundred couples of oil/pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards, etc. This paper presents a comparative analysis of these ten years of experience. This analysis provides, among other results, a critical Electrostatic Hazard assessment in transformers and an attempt of discrimination tentative of a suspected transformer.
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Electrostatic Hazard in High Power Transformers: Analyze of Ten Years of the Capacitive Sensor
2012Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain Tanguy, Clamart Cedex FranceAbstract:Abstract-- In high power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta and dissolved gases measurement... At P ' institute of Poitiers an original sensor was developed used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for 10 years, this bench has been used to study over a hundred couples of oil / pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards…. The paper presents a comparative analysis of these 10 years of experience. This analysis provides, among other results, a critical Electrostatic Hazards assessment in transformers and an attempt of discrimination tentative of a suspected transformer Index Terms—Flow electrification, Hazard, power transformer. I
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High Power Transformers Failures due to Flow Electrification: Tools for Understanding the Electrostatic Hazard
2009Co-Authors: Thierry Paillat, J.m. Cabaleiro, M. El-adawy, O. Moreau, Gérard TouchardAbstract:Flow electrification phenomenon is suspected to be responsible for some failures in high power transformers. Acoustic sensor surveys from suspected transformers and visual observations in damaged transformers revealed some evidences of electrical discharges (electric "tree" paths, "worm holes", presence of carbon ...) on inner pressboards. Nevertheless the scenario, which lays the Electrostatic activity and consequently transformer failure, is still not well understood. The goal of this work is to propose some elements for understanding Electrostatic Hazards in high power transformers. Experimental set up has been developed in our laboratory to study flow electrification of oil at a pressboard rectangular duct. As in power transformers, the oil/pressboard couple is insulated from the ground by an oil volume. Pressboard potential, accumulated charges on pressboard surface are recorded and correlated to charge leakage.
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Analysis of flow electrification parameters of power transformer oils
2008 IEEE International Conference on Dielectric Liquids, 2008Co-Authors: R. Vaucelle, Thierry Paillat, J.m. Cabaleiro, O. Moreau, Y. Bertrand, Gérard TouchardAbstract:As a part of a research program at EDF, University of Poitiers has developed a prototype of a sensor dedicated to the monitoring of oil flow electrification through transformer pressboard-made channels. This phenomenon can be responsible for destructive breakdowns when the resulting charge accumulation leads to high electrical fields. In order to identify transformers running Electrostatic Hazards, an experimental setup been has developed to measure the generation and the accumulation on pressboard surface of electric charges with regard to different oil flow conditions (velocity, temperature). Various oils have been characterized with the same reference pressboard: new oils and oils coming from operating transformers (healthy or suspected to develop the phenomenon). The analysis of the measured parameters makes it possible to derive some criteria with regard to the Electrostatic Hazard probability in transformers.
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Flow electrification in power transformers: salt-type additive as a potential remedy?
Journal of Electrostatics, 2005Co-Authors: Audrey Bourgeois, Thierry Paillat, Olivier Moreau, Gérard Mortha, Gérard TouchardAbstract:Flow electrification in power transformers has been studied for the last 30 years, since the charge generation phenomenon was suspected to be responsible for power transformer failures. An experimental set-up has been built at the University of Poitiers in partnership with EDF (French utility) to simulate the oil path along the pressboard between transformer windings. The accumulated charge in a pressboard duct can then be estimated by the integration of the measured capacitive current up to infinite time. Among the investigations to reduce the Electrostatic Hazard, a chemical salt has been injected into new and aged oil at different concentrations. It was found that the accumulated charge was drastically reduced at different salt concentrations for both oils whatever the temperature and the flow rate applied.
Ciampi Simone - One of the best experts on this subject based on the ideXlab platform.
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Static Electrification of Plastics under Friction: The Position of Engineering-Grade Polyethylene Terephthalate in the Triboelectric Series
'Wiley', 2020Co-Authors: Zhang Jinyang, Darwish Nadim, Coote Michelle, Ciampi SimoneAbstract:There is an emerging trend to replace moving metallic parts, such as bearings or bushes, with plastic components. The Electrostatic Hazard associated with plastic components subject to mechanical friction is well documented, but the magnitude as well as physical–chemical origin of this phenomenon remains debated. Using atomic force microscopy and Faraday pail measurements, the triboelectrification of Ertalyte®, a commonly used bearing-grade formulation of polyethylene terephthalate, when rubbed against other polymers and metals, is studied. The sign and magnitude of the net charge that Ertalyte® gains in relation to the chemical nature—electron affinity and ionization energy—of the contacting material are analyzed, concluding that this material should be located toward the negative end of the triboelectric series. It is also shown that large charge densities and fast charge decays result from contact of Ertalyte® with polymers of a small Derjaguin–Muller–Toporov (DMT) modulus and unstable ions, suggesting that ion transfer leads to the electrification of a dynamic insulator/insulator contact. These findings have immediate implications in the choice of the material used to manufacture plastic parts subject to friction and wear and to help address ongoing fundamental questions over the nature of the charge carriers that leads to static electricityThis work was financially supported by the Australian Research Council (DE160100732 (S.C.), DE160101101 (N.D.), DP190100735 (S.C and N.D.), and FL170100041 (M.L.C))
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Static Electrification of Plastics under Friction: The Position of Engineering-Grade Polyethylene Terephthalate in the Triboelectric Series
'Wiley', 2020Co-Authors: Zhang Jinyang, Darwish Nadim, Coote M.l., Ciampi SimoneAbstract:© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim There is an emerging trend to replace moving metallic parts, such as bearings or bushes, with plastic components. The Electrostatic Hazard associated with plastic components subject to mechanical friction is well documented, but the magnitude as well as physical–chemical origin of this phenomenon remains debated. Using atomic force microscopy and Faraday pail measurements, the triboelectrification of Ertalyte®, a commonly used bearing-grade formulation of polyethylene terephthalate, when rubbed against other polymers and metals, is studied. The sign and magnitude of the net charge that Ertalyte® gains in relation to the chemical nature—electron affinity and ionization energy—of the contacting material are analyzed, concluding that this material should be located toward the negative end of the triboelectric series. It is also shown that large charge densities and fast charge decays result from contact of Ertalyte® with polymers of a small Derjaguin–Muller–Toporov (DMT) modulus and unstable ions, suggesting that ion transfer leads to the electrification of a dynamic insulator/insulator contact. These findings have immediate implications in the choice of the material used to manufacture plastic parts subject to friction and wear and to help address ongoing fundamental questions over the nature of the charge carriers that leads to static electricity
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The position of solid carbon dioxide in the triboelectric series
'CSIRO Publishing', 2019Co-Authors: Zhang Jinyang, Ciampi SimoneAbstract:© 2019 CSIRO. The process of releasing liquid carbon dioxide from a fire extinguisher is accompanied by a strong static charging of the plastic material making up the extinguisher discharge horn. Firefighters often report an electric shock when operating CO2 extinguishers, but the origin of this Electrostatic Hazard is largely unknown. Here, we begin to investigate this phenomenon, and test the hypothesis of plastic samples being tribocharged on contact with rapidly flowing solid CO2. Using Faraday pail measurements, we show that non-conductive polymers gain a net static charge when brought in and out of contact with dry ice (solid CO2). These measurements of charge sign and magnitude give indirect evidence helping to place solid CO2 for the first time on the triboelectric series. Polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC) samples acquire a negative charge when rubbed against dry ice, whereas poly(methyl methacrylate) (PMMA), glass, and nylon surfaces become positively charged. Therefore, we suggest the position of dry ice in the triboelectric series to be close to that of materials with stable cations and unstable anions, possibly locating it between PMMA and PVC
L Dascalescu - One of the best experts on this subject based on the ideXlab platform.
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sinusoidal and triangular high voltage neutralizers for accelerated discharge of nonwoven fibrous dielectrics
IEEE Transactions on Industry Applications, 2012Co-Authors: Angela Antoniu, Atallah Smaili, I Vacar, Mariuscristian Plopeanu, L DascalescuAbstract:Electric charge accumulation on fibrous dielectric media during manufacturing processes can easily attain high levels of Electrostatic Hazard. In a previous paper, the authors addressed the problem of the accelerated discharge of such materials using a commercial ion generator. The aim of this paper is to evaluate the various factors that influence the efficiency of charge neutralization performed using a wire-type corona electrode energized from either a sinusoidal or a triangular ac high-voltage supply. The experiments were performed on 400-μm-thick nonwoven sheets of polypropylene and polyester, in ambient air. The samples were charged for 10 s using a triode-type corona electrode system of negative polarity. The surface potential on the charged medium, which was in contact with the grounded electrode, was then measured with an Electrostatic voltmeter. After 10 min, the medium was moved beneath a neutralizing electrode, connected to a high-voltage amplifier. The efficiency of the neutralization was quantified by the ratio between the surface potential after and prior to the charged sample exposure to ac corona discharge. The experimental design methodology was employed for evaluating the effects of two factors, namely, amplitude (range: 16-24 kV) and frequency (range: 20-400 Hz), of the neutralizing voltage. The potential at the surface of the nonwoven fabrics after neutralization was found to vary insignificantly with thermal conditioning and signal waveform but was significantly lower for higher frequencies and amplitudes.
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sinusoidal and triangular high voltage neutralizers for accelerated discharge of non woven fibrous dielectrics
IEEE Industry Applications Society Annual Meeting, 2011Co-Authors: Angela Antoniu, Atallah Smaili, I Vacar, Mariuscristian Plopeanu, L DascalescuAbstract:Electric charge accumulation on fibrous dielectric media during manufacturing processes can easily attain high levels of Electrostatic Hazard. In a previous paper, the authors addressed the problem of the accelerated discharge of such materials using a commercial ion generator. The aim of the present work is to evaluate the various factors that influence the efficiency of charge neutralization performed using a wire-type corona electrode energized from either a sinusoidal or a triangular AC high-voltage supply. The experiments were performed on 400 µm-thick non-weaved sheets of polypropylene and polyester, in ambient air. The samples were charged for 10 seconds using a triode - type corona electrode system of negative polarity. The surface potential on the charged media, which was in contact with the grounded electrode, was then measured with an Electrostatic voltmeter. After 10 minutes, the media was moved beneath a neutralizing electrode, connected to a high-voltage amplifier. The efficiency of the neutralization was quantified by the ratio between the surface potential after and prior the charged sample exposure to AC corona discharge. The experimental design methodology was employed for evaluating the effects of two factors: amplitude (range: 16 to 24 kV) and frequency (range: 20 to 400 Hz) of the neutralizing voltage. The potential at the surface of the non-woven fabrics after neutralization was found to vary insignificantly with thermal conditioning and signal waveform, but was significantly lower for higher frequencies and amplitudes.
Olivier Moreau - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic Hazard in High-Power Transformers: Results of Ten Years of Experience With ${P}^{\prime}$ Capacitive Sensor
IEEE Transactions on Industry Applications, 2013Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain TanguyAbstract:In a high-power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta, dissolved gas measurement, etc. At P' Institute of Poitiers, an original sensor was developed and used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for ten years, this bench has been used to study over a hundred couples of oil/pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards, etc. This paper presents a comparative analysis of these ten years of experience. This analysis provides, among other results, a critical Electrostatic Hazard assessment in transformers and an attempt of discrimination tentative of a suspected transformer.
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Electrostatic Hazard in High Power Transformers: Analyze of Ten Years of the Capacitive Sensor
2012Co-Authors: Thierry Paillat, Olivier Moreau, Gérard Touchard, Gerard Morin, Yves Bertrand, Alain Tanguy, Clamart Cedex FranceAbstract:Abstract-- In high power transformer, oil flowing on pressboard surface is suspected to be responsible of Electrostatic Hazards and failures. Different methods of risk assessment have been proposed to understand and prevent it: ministatic tester in the Westinghouse protocol, ministatic tester in the spinning disk measurement, monitoring of tangent delta and dissolved gases measurement... At P ' institute of Poitiers an original sensor was developed used for quantification of the electric charge generated and of accumulated charge for an oil flow onto the surface of a transformer pressboard insulated from ground. Operational for 10 years, this bench has been used to study over a hundred couples of oil / pressboard, pairs of new oil and pressboard, pairs of aged oil and pressboard, pairs of suspicious oil and pressboards…. The paper presents a comparative analysis of these 10 years of experience. This analysis provides, among other results, a critical Electrostatic Hazards assessment in transformers and an attempt of discrimination tentative of a suspected transformer Index Terms—Flow electrification, Hazard, power transformer. I
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Flow electrification in power transformers: salt-type additive as a potential remedy?
Journal of Electrostatics, 2005Co-Authors: Audrey Bourgeois, Thierry Paillat, Olivier Moreau, Gérard Mortha, Gérard TouchardAbstract:Flow electrification in power transformers has been studied for the last 30 years, since the charge generation phenomenon was suspected to be responsible for power transformer failures. An experimental set-up has been built at the University of Poitiers in partnership with EDF (French utility) to simulate the oil path along the pressboard between transformer windings. The accumulated charge in a pressboard duct can then be estimated by the integration of the measured capacitive current up to infinite time. Among the investigations to reduce the Electrostatic Hazard, a chemical salt has been injected into new and aged oil at different concentrations. It was found that the accumulated charge was drastically reduced at different salt concentrations for both oils whatever the temperature and the flow rate applied.
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Flow Electrification in Transformers: Sensor Prototype for Electrostatic Hazard
2004Co-Authors: Olivier Moreau, Thierry Paillat, Gérard TouchardAbstract:As far as Static Electrification diagnosis in transformers is concerned, previous works have shown that the commonly applied measurements (leakage currents, Electrostatic Charging Tendency or ageing test for tan˜) were not completely reliable. As part of the research program of Electricite de France, a prototype of a new sensor dedicated to characterization of the phenomenon, when pressboard-oil insulation is present, has been developed with the University of Poitiers. To simulate the pressboard-made channels inside transformer, this device consists in a small pressboard with facilities for measuring reliable parameters related to the generation (accumulated charge) and leakage (leakage current) phases of the phenomenon. As it was likely to be installed on a real transformer, the sensor has been inserted, for its development, in a loop representing at a small- scale the oil path in a transformer with "on line" conductivity and moisture content monitoring. This complete setup has made it possible to investigate the parameters behaviour with regard to oil temperature and velocity during transient and steady states with and without flow. A first electrical model for the electro-kinetics of the sensor has been deduced from the analysis of the results. This device seems a promising tool to predict Electrostatic Hazards and to derive criteria for Static Electrification diagnosis in transformers.