The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Ruijin Liao - One of the best experts on this subject based on the ideXlab platform.

  • improvement of the space charge suppression and hydrophobicity property of Cellulose Insulation pressboard by surface sputtering a zno ptfe functional film
    Polymers, 2019
    Co-Authors: Yanqing Li, Jinfeng Zhang, Ruijin Liao
    Abstract:

    Oil-impregnated Cellulose Insulation polymer (oil-paper/pressboard Insulation) has been widely used in power transformers. Establishing effective ways of improving the physical and chemical properties of the Cellulose Insulation polymer is currently a popular research topic. In order to improve the charge injection inhibition and hydrophobic properties of the Cellulose Insulation polymer used in power transformers, nano-structure zinc oxide (ZnO) and polytetrafluoroethylene (PTFE) films were fabricated on a Cellulose Insulation pressboard surface via reactive radio frequency (RF) magnetron sputtering. Before the fabrication of their composite film, Accelrys Materials Studio (MS) software was applied to simulate the interaction between the nanoparticles and Cellulose molecules to determine the depositing sequence. Simulation results show that the ZnO nanoparticle has a better adhesion strength with Cellulose molecules than the PTFE nanoparticle, so ZnO film should be sputtered at first to fabricate the ZnO/PTFE composite film for better film quality. The sputtered, thin films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The space charge injection behavior and the hydrophobicity performance of the untreated pressboard; and the Cellulose Insulation pressboard with sputtered nano-structure ZnO, PTFE, and the ZnO/PTFE functional films were compared with each other. X-ray photoelectron spectroscopy results showed that ZnO, PTFE, and ZnO/PTFE functional films were all successfully fabricated on the Cellulose Insulation pressboard surface. Scanning electron microscopy and XRD results present the nano-structure of the sputtered ZnO, PTFE, and ZnO/PTFE functional films and their amorphous states, respectively. The ZnO/PTFE composite functional film shows an apparent space charge suppression effect and hydrophobicity. The amount of the accumulated space charge in the pressboard sputtered ZnO/PTFE composite functional film decreased by about 40% compared with that in untreated Cellulose Insulation pressboard, and the water contact angle (WCA) increased from 0° to 116°.

  • Improvement of the Space Charge Suppression and Hydrophobicity Property of Cellulose Insulation Pressboard by Surface Sputtering a ZnO/PTFE Functional Film.
    Polymers, 2019
    Co-Authors: Yanqing Li, Jinfeng Zhang, Ruijin Liao
    Abstract:

    Oil-impregnated Cellulose Insulation polymer (oil-paper/pressboard Insulation) has been widely used in power transformers. Establishing effective ways of improving the physical and chemical properties of the Cellulose Insulation polymer is currently a popular research topic. In order to improve the charge injection inhibition and hydrophobic properties of the Cellulose Insulation polymer used in power transformers, nano-structure zinc oxide (ZnO) and polytetrafluoroethylene (PTFE) films were fabricated on a Cellulose Insulation pressboard surface via reactive radio frequency (RF) magnetron sputtering. Before the fabrication of their composite film, Accelrys Materials Studio (MS) software was applied to simulate the interaction between the nanoparticles and Cellulose molecules to determine the depositing sequence. Simulation results show that the ZnO nanoparticle has a better adhesion strength with Cellulose molecules than the PTFE nanoparticle, so ZnO film should be sputtered at first to fabricate the ZnO/PTFE composite film for better film quality. The sputtered, thin films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The space charge injection behavior and the hydrophobicity performance of the untreated pressboard; and the Cellulose Insulation pressboard with sputtered nano-structure ZnO, PTFE, and the ZnO/PTFE functional films were compared with each other. X-ray photoelectron spectroscopy results showed that ZnO, PTFE, and ZnO/PTFE functional films were all successfully fabricated on the Cellulose Insulation pressboard surface. Scanning electron microscopy and XRD results present the nano-structure of the sputtered ZnO, PTFE, and ZnO/PTFE functional films and their amorphous states, respectively. The ZnO/PTFE composite functional film shows an apparent space charge suppression effect and hydrophobicity. The amount of the accumulated space charge in the pressboard sputtered ZnO/PTFE composite functional film decreased by about 40% compared with that in untreated Cellulose Insulation pressboard, and the water contact angle (WCA) increased from 0° to 116°.

  • fabrication of zno al2o3 ptfe multilayer nano structured functional film on Cellulose Insulation polymer surface and its effect on moisture inhibition and dielectric properties
    Polymers, 2019
    Co-Authors: Yanqing Li, Ruijin Liao
    Abstract:

    After a century of practice, Cellulose insulating polymer (insulating paper/pressboard) has been shown to be one of the best and most widely used insulating materials in power transformers. However, with the increased voltage level of the transformer, research has focused on improving the Insulation performance of the transformer’s Cellulose Insulation polymer. Considering the complex environment of the transformer, it is not enough to improve the single performance of the insulating polymer. In this study, a nano-structured ZnO-Al2O3-PTFE (polytetrafluoroethylene) multifunctional film was deposited on the surface of insulating pressboard by radio frequency (RF) magnetron sputtering. The effect of the multilayered ZnO-Al2O3-PTFE functional film on the dielectric and water contact angle of the Cellulose insulating polymer was investigated. The scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) showed that the nano-structured ZnO-Al2O3-PTFE functional film was successfully deposited on the Cellulose Insulation pressboard surface. The functional film presented an obvious stratification phenomenon. By analyzing the result of the contact angle, it was found that the functional film shields the hydroxyl group of the inner Cellulose and improves hydrophobicity. The AC breakdown field strength of the treated samples was obviously increased (by 12 to ~17%), which means that the modified samples had a better dielectric Insulation performance. This study provides a surface modification method to comprehensively improve electrical properties and the ability to inhibit the moisture of the Cellulose insulating polymer, used in a power transformer.

  • comparative study on the thermal aging characteristics of Cellulose Insulation polymer immersed in new three element mixed oil and mineral oil
    Polymers, 2019
    Co-Authors: Dawei Feng, Ruijin Liao, Xin Chen, Lin Cheng
    Abstract:

    Cellulose paper, whose main component is Cellulose polymer, has been widely used in oil-immersed power transformer that gradually deteriorates during transformer operation. Thermal aging is the main degradation form for Cellulose paper immersed in Insulation oil (oil–paper Insulation) in a transformer. One of the most challenging issues in oil–paper Insulation is inhibiting the aging of Cellulose paper and extending its life. In this work, a comparative study was conducted on the thermal-aging characteristics of Cellulose paper immersed in a novel three-element mixed Insulation oil and mineral oil at 130 °C for 150 days. The key parameters of Cellulose paper were analysed, including the degree of polymerization (DP), thermal-aging rate, surface colour, and AC breakdown voltage. The furfural content and acidity of the oil, as well as the AC breakdown voltage of the Insulation oil were also analysed. The results show that the Cellulose paper immersed in novel three-element mixed Insulation oil had much higher DP values than that immersed in mineral oil after the same thermal-aging time. The mixed Insulation oil could significantly inhibit the thermal aging of Cellulose paper and prolong its life. The thermal-aging rate of the Cellulose Insulation polymer immersed in mixed Insulation oil is significantly lower than that immersed in mineral oil, whether in the process of oil–paper Insulation continuous aging or in the process of aging after oil replacement with unused Insulation oil. The furfural generated by Cellulose degradation in the novel three-element mixed Insulation oil was also less than that in the mineral oil. The mixed Insulation oil had a higher acidity value during the thermal-aging process, which was mainly due to the natural esters in the components of the mixed Insulation oil. However, the AC breakdown voltage of the mixed Insulation oil was always higher than that of the mineral oil. This study offers a new perspective in inhibiting the thermal aging of Cellulose polymer in Insulation oil.

  • AC Surface Flashover and Gas Generation Difference of the Cellulose Insulation Pressboard Immersed in Novel 3-Element Mixed Oil and Mineral Oil
    IEEE Access, 2019
    Co-Authors: Xin Chen, Ruijin Liao, Jian Li, Lijun Yang, Dawei Feng
    Abstract:

    Surface flashover fault is one of the most challenge issues in oil-Cellulose Insulation pressboard system used in power transformer. In this study, a comparative study of the AC surface flashover properties of the novel 3-element mixed oil-Cellulose Insulation pressboard (3EMO-IP) and mineral oil-Cellulose Insulation pressboard (MO-IP) was performed under needle-plate and finger-finger electrode, respectively, measurement including dielectric property, surface flashover voltage, damage of Cellulose pressboard surface and the gas generation behaviors after multiple surface flashover. Results show that the Cellulose Insulation pressboard immersed in the novel 3-element mixed Insulation oil (3EMO) has higher relative permittivity and dielectric loss factor at 50 Hz, and also has slightly lower surface resistivity. The AC surface flashover voltage of the 3EMO-IP is higher than that of MO-IP under needle-plate and finger-finger electrode (electrode distance 5 mm, 10 mm, 15 mm and 20 mm). Compared to MO-IP, the lower electric field intensity at the oil-pressboard interface, as well as more difficult for surface charge accumulation of 3EMO-IP and the higher breakdown voltage of 3EMO lead to the higher AC surface flashover voltage of 3EMO-IP. Moreover, the carbonization of fibers in 3EMO-IP is slightly less. After multiple surface flashover, C2H2 and total hydrocarbon gases are the main differences between 3EMO-IP and MO-IP, which is more marked with the increase of flashover times. This study offers a reference for improving the surface flashover property of oil-pressboard Insulation system by using 3EMO.

Yanqing Li - One of the best experts on this subject based on the ideXlab platform.

  • improvement of the space charge suppression and hydrophobicity property of Cellulose Insulation pressboard by surface sputtering a zno ptfe functional film
    Polymers, 2019
    Co-Authors: Yanqing Li, Jinfeng Zhang, Ruijin Liao
    Abstract:

    Oil-impregnated Cellulose Insulation polymer (oil-paper/pressboard Insulation) has been widely used in power transformers. Establishing effective ways of improving the physical and chemical properties of the Cellulose Insulation polymer is currently a popular research topic. In order to improve the charge injection inhibition and hydrophobic properties of the Cellulose Insulation polymer used in power transformers, nano-structure zinc oxide (ZnO) and polytetrafluoroethylene (PTFE) films were fabricated on a Cellulose Insulation pressboard surface via reactive radio frequency (RF) magnetron sputtering. Before the fabrication of their composite film, Accelrys Materials Studio (MS) software was applied to simulate the interaction between the nanoparticles and Cellulose molecules to determine the depositing sequence. Simulation results show that the ZnO nanoparticle has a better adhesion strength with Cellulose molecules than the PTFE nanoparticle, so ZnO film should be sputtered at first to fabricate the ZnO/PTFE composite film for better film quality. The sputtered, thin films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The space charge injection behavior and the hydrophobicity performance of the untreated pressboard; and the Cellulose Insulation pressboard with sputtered nano-structure ZnO, PTFE, and the ZnO/PTFE functional films were compared with each other. X-ray photoelectron spectroscopy results showed that ZnO, PTFE, and ZnO/PTFE functional films were all successfully fabricated on the Cellulose Insulation pressboard surface. Scanning electron microscopy and XRD results present the nano-structure of the sputtered ZnO, PTFE, and ZnO/PTFE functional films and their amorphous states, respectively. The ZnO/PTFE composite functional film shows an apparent space charge suppression effect and hydrophobicity. The amount of the accumulated space charge in the pressboard sputtered ZnO/PTFE composite functional film decreased by about 40% compared with that in untreated Cellulose Insulation pressboard, and the water contact angle (WCA) increased from 0° to 116°.

  • Improvement of the Space Charge Suppression and Hydrophobicity Property of Cellulose Insulation Pressboard by Surface Sputtering a ZnO/PTFE Functional Film.
    Polymers, 2019
    Co-Authors: Yanqing Li, Jinfeng Zhang, Ruijin Liao
    Abstract:

    Oil-impregnated Cellulose Insulation polymer (oil-paper/pressboard Insulation) has been widely used in power transformers. Establishing effective ways of improving the physical and chemical properties of the Cellulose Insulation polymer is currently a popular research topic. In order to improve the charge injection inhibition and hydrophobic properties of the Cellulose Insulation polymer used in power transformers, nano-structure zinc oxide (ZnO) and polytetrafluoroethylene (PTFE) films were fabricated on a Cellulose Insulation pressboard surface via reactive radio frequency (RF) magnetron sputtering. Before the fabrication of their composite film, Accelrys Materials Studio (MS) software was applied to simulate the interaction between the nanoparticles and Cellulose molecules to determine the depositing sequence. Simulation results show that the ZnO nanoparticle has a better adhesion strength with Cellulose molecules than the PTFE nanoparticle, so ZnO film should be sputtered at first to fabricate the ZnO/PTFE composite film for better film quality. The sputtered, thin films were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The space charge injection behavior and the hydrophobicity performance of the untreated pressboard; and the Cellulose Insulation pressboard with sputtered nano-structure ZnO, PTFE, and the ZnO/PTFE functional films were compared with each other. X-ray photoelectron spectroscopy results showed that ZnO, PTFE, and ZnO/PTFE functional films were all successfully fabricated on the Cellulose Insulation pressboard surface. Scanning electron microscopy and XRD results present the nano-structure of the sputtered ZnO, PTFE, and ZnO/PTFE functional films and their amorphous states, respectively. The ZnO/PTFE composite functional film shows an apparent space charge suppression effect and hydrophobicity. The amount of the accumulated space charge in the pressboard sputtered ZnO/PTFE composite functional film decreased by about 40% compared with that in untreated Cellulose Insulation pressboard, and the water contact angle (WCA) increased from 0° to 116°.

  • fabrication of zno al2o3 ptfe multilayer nano structured functional film on Cellulose Insulation polymer surface and its effect on moisture inhibition and dielectric properties
    Polymers, 2019
    Co-Authors: Yanqing Li, Ruijin Liao
    Abstract:

    After a century of practice, Cellulose insulating polymer (insulating paper/pressboard) has been shown to be one of the best and most widely used insulating materials in power transformers. However, with the increased voltage level of the transformer, research has focused on improving the Insulation performance of the transformer’s Cellulose Insulation polymer. Considering the complex environment of the transformer, it is not enough to improve the single performance of the insulating polymer. In this study, a nano-structured ZnO-Al2O3-PTFE (polytetrafluoroethylene) multifunctional film was deposited on the surface of insulating pressboard by radio frequency (RF) magnetron sputtering. The effect of the multilayered ZnO-Al2O3-PTFE functional film on the dielectric and water contact angle of the Cellulose insulating polymer was investigated. The scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) showed that the nano-structured ZnO-Al2O3-PTFE functional film was successfully deposited on the Cellulose Insulation pressboard surface. The functional film presented an obvious stratification phenomenon. By analyzing the result of the contact angle, it was found that the functional film shields the hydroxyl group of the inner Cellulose and improves hydrophobicity. The AC breakdown field strength of the treated samples was obviously increased (by 12 to ~17%), which means that the modified samples had a better dielectric Insulation performance. This study provides a surface modification method to comprehensively improve electrical properties and the ability to inhibit the moisture of the Cellulose insulating polymer, used in a power transformer.

  • preparation nano structure polytetrafluoroethylene ptfe functional film on the Cellulose Insulation polymer and its effect on the breakdown voltage and hydrophobicity properties
    Materials, 2018
    Co-Authors: Yanqing Li, Ruijin Liao, Qiang Liao, Chao Tang
    Abstract:

    Cellulose Insulation polymer is an important component of oil-paper Insulation, which is widely used in power transformer. The weight of the Cellulose Insulation polymer materials is as high as tens of tons in the larger converter transformer. Excellent performance of oil-paper Insulation is very important for ensuring the safe operation of larger converter transformer. An effective way to improve the Insulation and the physicochemical property of the oil impregnated Insulation pressboard/paper is currently a popular research topic. In this paper, the polytetrafluoroethylene (PTFE) functional film was coated on the Cellulose Insulation pressboard by radio frequency (RF) magnetron sputtering to improve its breakdown voltage and the hydrophobicity properties. X-ray photoelectron spectroscopy (XPS) results show that the nano-structure PTFE functional film was successfully fabricated on the Cellulose Insulation pressboard surface. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) present that the nanoscale size PTFE particles were attached to the pressboard surface and it exists in the amorphous form. Atomic force microscopy (AFM) shows that the sputtered pressboard surface is still rough. The rough PTFE functional film and the reduction of the hydrophilic hydroxyl of the surface due to the shielding effect of PTFE improve the breakdown and the hydrophobicity properties of the Cellulose Insulation pressboard obviously. This paper provides an innovative way to improve the performance of the Cellulose Insulation polymer.

  • Fabrication of Al2O3 Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect
    Polymers, 2017
    Co-Authors: Yanqing Li, Ruijin Liao, Qiang Liao, Chao Tang
    Abstract:

    Cellulose Insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the Insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in Insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a Cellulose Insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al2O3 film with amorphous phase was successfully fabricated onto the fibre surface. The Cellulose Insulation pressboard surface sputtered by Al2O3 film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (

Chao Tang - One of the best experts on this subject based on the ideXlab platform.

  • preparation nano structure polytetrafluoroethylene ptfe functional film on the Cellulose Insulation polymer and its effect on the breakdown voltage and hydrophobicity properties
    Materials, 2018
    Co-Authors: Yanqing Li, Ruijin Liao, Qiang Liao, Chao Tang
    Abstract:

    Cellulose Insulation polymer is an important component of oil-paper Insulation, which is widely used in power transformer. The weight of the Cellulose Insulation polymer materials is as high as tens of tons in the larger converter transformer. Excellent performance of oil-paper Insulation is very important for ensuring the safe operation of larger converter transformer. An effective way to improve the Insulation and the physicochemical property of the oil impregnated Insulation pressboard/paper is currently a popular research topic. In this paper, the polytetrafluoroethylene (PTFE) functional film was coated on the Cellulose Insulation pressboard by radio frequency (RF) magnetron sputtering to improve its breakdown voltage and the hydrophobicity properties. X-ray photoelectron spectroscopy (XPS) results show that the nano-structure PTFE functional film was successfully fabricated on the Cellulose Insulation pressboard surface. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) present that the nanoscale size PTFE particles were attached to the pressboard surface and it exists in the amorphous form. Atomic force microscopy (AFM) shows that the sputtered pressboard surface is still rough. The rough PTFE functional film and the reduction of the hydrophilic hydroxyl of the surface due to the shielding effect of PTFE improve the breakdown and the hydrophobicity properties of the Cellulose Insulation pressboard obviously. This paper provides an innovative way to improve the performance of the Cellulose Insulation polymer.

  • enhanced mechanical properties and thermal stability of Cellulose Insulation paper achieved by doping with melamine grafted nano sio2
    Cellulose, 2018
    Co-Authors: Chao Tang, Song Zhang, Xiaobo Wang
    Abstract:

    In the long-term operation of power transformer, the traditional Cellulose Insulation paper undergoes aging phenomena, making it difficult for this type of paper to meet severe Insulation requirements. In this study, Cellulose is modified by doping with melamine-grafted nano-SiO2, and Cellulose/water (C–H2O), nano-SiO2-modified Cellulose/water (CN–H2O) and melamine-grafted nano-SiO2-modified Cellulose/water (CAN–H2O) models are developed. The results show that the mechanical properties of CN–H2O and CAN–H2O are improved relative to those of C–H2O and that CAN–H2O exhibits the best mechanical properties. Furthermore, the glass transition temperatures of CN–H2O and CAN–H2O are, respectively, 39 and 69 K, higher than that of C–H2O. Near the glass transition temperature, the mean square displacement of the water molecules changes considerably. Therefore, increasing the glass transition temperature and thus the thermal stability of Cellulose can be achieved by modifying Cellulose with melamine-grafted SiO2 nanoparticles. Experimental studies show that with an increase in the aging time, the moisture content in the modified Insulation paper will be less than that in the unmodified Insulation paper, while the tensile strength, degree of polymerization (DP) and breakdown strength were greater than that in the unmodified Insulation paper. In particular, the melamine-grafted nano-SiO2-modified Insulation paper has the lowest moisture content and highest tensile strength DP and breakdown strength during the entire aging time. Thus, this study shows that the thermal stability and electrical characteristics of the melamine-grafted nano-SiO2-modified Insulation paper is the highest at both the microscopic and macroscopic levels, indicating that this Insulation paper could meet the Insulation performance requirements of large transformers under high-temperature and high-pressure conditions.

  • Fabrication of Al2O3 Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect
    Polymers, 2017
    Co-Authors: Yanqing Li, Ruijin Liao, Qiang Liao, Chao Tang
    Abstract:

    Cellulose Insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the Insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in Insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a Cellulose Insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al2O3 film with amorphous phase was successfully fabricated onto the fibre surface. The Cellulose Insulation pressboard surface sputtered by Al2O3 film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (

  • fabrication of al2o3 nano structure functional film on a Cellulose Insulation polymer surface and its space charge suppression effect
    Polymers, 2017
    Co-Authors: Yanqing Li, Ruijin Liao, Qiang Liao, Chao Tang
    Abstract:

    Cellulose Insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the Insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in Insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a Cellulose Insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al2O3 film with amorphous phase was successfully fabricated onto the fibre surface. The Cellulose Insulation pressboard surface sputtered by Al2O3 film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (<103 Hz) region. The oil-impregnated sputtered pressboard presents an apparent space-charge suppression effect. Compared with the pressboard sputtered with Al2O3 film for 90 min, the pressboard sputtered with Al2O3 film for 60 min had a better space charge suppression effect. Ultra-small Al2O3 particles (<10 nm) grew on the surface of the larger nanoparticles. The nano-structured Al2O3 film sputtered on the fibre surface could act as a functional barrier layer for suppression of the charge injection and accumulation. This study offers a new perspective in favour of the application of Insulation pressboard with a nano-structured function surface against space charge injection/accumulation in HVDC equipment.

  • Molecular simulation and experimental analysis of Al2O3-nanoparticle-modified Insulation paper Cellulose
    IEEE Transactions on Dielectrics and Electrical Insulation, 2017
    Co-Authors: Chao Tang, Song Zhang, Cheng Lv
    Abstract:

    To improve the thermal stability of the Cellulose Insulation paper used in power transformers, Al2O3 nanoparticles were used to modify traditional Cellulose Insulation paper. Molecular simulations and experimental methods were used to analyze the enhancement and the microscopic mechanism of Al2O3 nanoparticles in the thermal aging process of Insulation paper. Molecular simulations were performed for an unmodified and a Al2O3 nanoparticle-modified Cellulose model to explore the changes in mechanical properties, cohesive energy densities and the glass transition temperatures of the two models in a temperature range of 70-150 °C. The results of these simulations showed that the elastic modulus of the Cellulose model modified with Al2O3 nanoparticles was larger than that of the unmodified model. Further, the addition of Al2O3 nanoparticles increased the glass transition temperature, signifying that the number of hydrogen bond connections was increased and the thermal stability of the modified model was improved. In addition, physical samples of modified Insulation papers mixed with Al2O3 nanoparticles were made, and accelerated thermal aging experiments on these samples showed that the decrease in the degree of polymerization for the modified Insulation paper was slower than that of the unmodified Insulation paper. Further, breakdown tests suggested that the addition of Al2O3 nanoparticles has a certain positive effect on the AC breakdown voltage. Both the simulated and experimental results indicate that the addition of Al2O3 nanoparticles improves the thermal aging performance of Cellulose Insulation paper.

T K Saha - One of the best experts on this subject based on the ideXlab platform.

  • a study of the degradation of cellulosic Insulation materials in a power transformer part iii degradation products of Cellulose Insulation paper
    Polymer Degradation and Stability, 1996
    Co-Authors: David J Hill, T T Le, M Darveniza, T K Saha
    Abstract:

    The cellulosic Insulation materials in operational transformers undergo a slow thermal degradation during the life-time of the transformer to form furans which dissolve in the Insulation oil of the transformer. There are six furans formed in significant quantity in an operational transformer. They are 2-furfuraldehyde, 5-hydroxymethyl-2-furfuraldehyde, 2-methyl-furfuraldehyde, 2-acetyl furan, 2-furoic acid and furfuryl alcohol. The concentrations of these furans can be measured by HPLC analysis of the oil. In this paper the furan products formed by accelerated ageing of Cellulose Insulation paper in Shell Diala B transformer Insulation oil over the temperature range 130–170 °C are investigated, and the results have been correlated with those observed for the changes in the molecular weight and tensile strength of the Insulation paper.

  • a study of degradation of cellulosic Insulation materials in a power transformer part 2 tensile strength of Cellulose Insulation paper
    Polymer Degradation and Stability, 1995
    Co-Authors: David J Hill, T T Le, M Darveniza, T K Saha
    Abstract:

    When Cellulose Insulation paper ages, its physical and chemical properties change, the paper loses its strength and becomes brittle. A study of the accelerated ageing of cellulosic Insulation paper in Insulation oil has been performed in the temperature range 129–166 °C under vacuum. The tensile strength of paper that has been subjected to accelerated ageing as well as of paper retrieved from a retired transformer were measured in the cross machine direction (CMD). The results were found to be consistent with the observed changes in the molecular weight of the Insulation paper. The relationship between tensile strength and molecular weight has been delineated and correlated with information on the kinetics of degradation of the Insulation paper.

  • a study of degradation of cellulosic Insulation materials in a power transformer part 1 molecular weight study of Cellulose Insulation paper
    Polymer Degradation and Stability, 1995
    Co-Authors: David J Hill, T T Le, M Darveniza, T K Saha
    Abstract:

    As a transformer ages, the chemical and physical properties of the Cellulose Insulation paper will change. For example, the average molecular weight of the Cellulose chains decreases with age, as does the strength of the Insulation paper. The molecular weight changes can be studied by several methods. However, the GPC method reported in this paper has an advantage over the other methods because it yields the total molecular weight distribution. In order to understand the mechanism of the degradation of the cellulosic Insulation materials in a power transformer, a study of the accelerated ageing of cellulosic Insulation paper in Insulation oil has been performed in the temperature range 129–166 °C, under vacuum. The molecular weight and molecular weight distribution of the Cellulose chains present in the Insulation paper were measured by GPC techniques. The results provide information on the kinetics of degradation of the Insulation paper. The results of the molecular weight study in the accelerated ageing experiments were found to be most useful for monitoring the condition of the Insulation paper in an operational transformer.

  • gel permeation chromatography of the thermal degradation of Cellulose Insulation paper in an aged power transformer
    Australian polymer symposium, 1992
    Co-Authors: David J Hill, T T Le, M Darveniza, T K Saha, B Williams
    Abstract:

    The lifetime of a power transformer and its capacity to be refurbished is often determined by the condition of the Cellulose Insulation materials used to wrap the copper windings. As a transformer ages the molecular weight of the Cellulose in the Insulation paper decreases. Here we describe a study of the accelerated ageing of Cellulose Insulation paper and cotton linter under vacuum at 166°C. The study indicates that the degradation results in a bimodal distribution in molecular weight of the Cellulose, which indicates that the scission of bonds in the Cellulose chains is non-random, and bonds near the middle of the chains have a higher probability of bond scission than those near the ends. This has been associated with the rod-like structure of the Cellulose molecules.

Hanbo Zheng - One of the best experts on this subject based on the ideXlab platform.

  • a modified x model of the oil impregnated bushing including non uniform thermal aging of Cellulose Insulation
    Cellulose, 2020
    Co-Authors: Shichang Yang, Yiyi Zhang, Hanbo Zheng, Chaohai Zhang
    Abstract:

    The frequency domain spectroscopy (FDS) technique is widely used for the aging condition assessment of Cellulose Insulation on the bushing core. Generally, these assessment activities could be completed by the analysis of the FDS data between the laboratory sample and field bushing with the help of the traditional X-model. However, the aging condition of Cellulose Insulation on the bushing core is non-uniform due to the existence of temperature gradient. In this case, the traditional X-model is considered inappropriate since it ignored the effect of non-uniform thermal aging. In view of this issue, a modified X-model is reported in this work. Relying on the theoretical analysis of the modified X-model, both the mathematical expression and the equivalent circuit is derived naturally. The reliability of the modified X-model is confirmed by the experimental researches. In addition, the effect of aluminum foil in the modified X-model on FDS data was also studied. Findings reveal that the addition of aluminum foil would cause a slight deviation of the FDS curves. Therefore, the modified X-model might utilize to study the information of the non-uniform thermal aging. In that respect, the contribution of this work is in the exploration of the modified X-model as a potential tool for connecting FDS data corresponding to the lab condition and field condition including non-uniform thermal aging of Cellulose Insulation on the bushing core.

  • quantitative evaluation for moisture content of Cellulose Insulation material in paper oil system based on frequency dielectric modulus technique
    Cellulose, 2020
    Co-Authors: Yiyi Zhang, Hanbo Zheng
    Abstract:

    The moisture evaluation of Cellulose Insulation material in paper/oil system based on the frequency dielectric spectroscopy (FDS) technique has been of great interest to researchers. However, the electrode polarization effect and conductance effect can “obscure” the relaxation information in the course of the traditional FDS test, which often leads to an unreliable result. The existing researches indicated that the frequency dielectric modulus-M*(ω) could effectively enable the investigation of the relaxation behavior, which might be used to realize the condition evaluation of Cellulose Insulation materials in paper/oil system. Unfortunately, the M*(ω) has been rarely exploited to evaluate the moisture content (mc%) of Cellulose Insulation material, and the study on approach for extracting characteristic parameters based on the M*(ω) is also rare. In view of this issue, the present contribution attempt to report an available approach for extracting the characteristic parameters based on the M*(ω), and further investigate the variation laws of mc% versus the above parameters. The findings reveal that the quantitative relationship between mc% and the above parameters can be established by fitting analysis. The feasibility of the proposed parameters for moisture evaluation of Cellulose Insulation material is demonstrated by the newly prepared Cellulose Insulation samples. It is interesting to note that the average percentage errors of evaluation results corresponding to the relaxation time constant (τM) and integral value (IV) of the real part of M*(ω) are less than 8%. In that respect, the novelty of this work is that the τM and IV might be used as a potential tool for quantitative evaluation of mc% of Cellulose Insulation in paper/oil systems.

  • Temperature correction to dielectric modulus and activation energy prediction of oil-immersed Cellulose Insulation
    IEEE Transactions on Dielectrics and Electrical Insulation, 2020
    Co-Authors: Yiyi Zhang, Hanbo Zheng, Jian Jiao
    Abstract:

    The dielectric modulus M*(ω) is used for studying the frequency domain response and activation energy (Ea) of transformer immersed Cellulose Insulation. Existing literatures show that the temperature is a crucial factor affecting the M*(ω) and aging rate of transformer oil-paper Insulation, while the Ea can be regarded as an indicator to reflect the average aging rate of the transformer immersed Cellulose Insulation. Therefore, the discussion of the temperature-dependence on both M*(ω) and Ea is of great significance. This paper attempts to report an approach for understanding the temperature impact on both M*(ω) and Ea. The obtained knowledge can be used to establish two available models for temperature correction on M*(ω) and activation energy prediction of transform immersed Cellulose Insulation, respectively. These findings are expected to promote the reliability of the condition prediction result of transformer immersed Cellulose Insulation by using M*(ω) and Ea technique.

  • Condition prediction for oil-immersed Cellulose Insulation in field transformer using fitting fingerprint database
    IEEE Transactions on Dielectrics and Electrical Insulation, 2020
    Co-Authors: Yiyi Zhang, Hanbo Zheng, Chaohai Zhang
    Abstract:

    The results of frequency domain spectroscopy (FDS) will be affected by moisture which often leads to an unreliable condition prediction of oil-immersed Cellulose Insulation in transformers. In view of this, a solution is proposed in this study by adopting a fitting fingerprint database (FFD) technique, which can be utilized for condition prediction of aging and moisture content. In the current work, the relevant fingerprints that could characterize the Insulation aging condition and moisture content are extracted from the FDS curves and the DC conductivity of the transformer oil. The FFD is then constructed by fitting fingerprints. The accuracy of the reported FFD technique is verified from tests on oil-immersed pressboard prepared in the lab and a transformer from the field. In this respect, the present contribution highlights FFD might be used as a powerful tool for condition prediction of oil-immersed Cellulose Insulation in transformers.

  • Quantitative evaluation for moisture content of Cellulose Insulation material in paper/oil system based on frequency dielectric modulus technique
    Cellulose, 2019
    Co-Authors: Yiyi Zhang, Hanbo Zheng
    Abstract:

    The moisture evaluation of Cellulose Insulation material in paper/oil system based on the frequency dielectric spectroscopy (FDS) technique has been of great interest to researchers. However, the electrode polarization effect and conductance effect can “obscure” the relaxation information in the course of the traditional FDS test, which often leads to an unreliable result. The existing researches indicated that the frequency dielectric modulus-M*(ω) could effectively enable the investigation of the relaxation behavior, which might be used to realize the condition evaluation of Cellulose Insulation materials in paper/oil system. Unfortunately, the M*(ω) has been rarely exploited to evaluate the moisture content (mc%) of Cellulose Insulation material, and the study on approach for extracting characteristic parameters based on the M*(ω) is also rare. In view of this issue, the present contribution attempt to report an available approach for extracting the characteristic parameters based on the M*(ω), and further investigate the variation laws of mc% versus the above parameters. The findings reveal that the quantitative relationship between mc% and the above parameters can be established by fitting analysis. The feasibility of the proposed parameters for moisture evaluation of Cellulose Insulation material is demonstrated by the newly prepared Cellulose Insulation samples. It is interesting to note that the average percentage errors of evaluation results corresponding to the relaxation time constant (τM) and integral value (IV) of the real part of M*(ω) are less than 8%. In that respect, the novelty of this work is that the τM and IV might be used as a potential tool for quantitative evaluation of mc% of Cellulose Insulation in paper/oil systems.