602,540 results
Search Results
202. Ageing rate of paper insulation used in power transformers Part 1: Oil/paper system with low oxygen concentration.
- Author
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Lelekakis, Nick, Martin, Daniel, and Wijaya, Jaury
- Subjects
ELECTRIC insulators & insulation ,ELECTRIC transformers ,OXYGEN ,ELECTRIC industries ,TEMPERATURE effect ,HYDROLYSIS ,MATHEMATICAL models - Abstract
A substantial quantity of testing has been performed on the degradation of paper insulation over the decades. The aim being to better educate the electrical industry on how to best operate expensive assets, such as transformers. The longevity of paper insulation is frequently tested using accelerated ageing experiments, where the effects of temperature and the chemical environment on paper lifespan can be studied. Such research has resulted in paper life expectancy curves being published by the IEEE and the IEC. The investigations tend to use sealed vessels. However, the disadvantage of using this method is that the water content of the paper changes during the ageing process which then changes the ageing rate. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the rate of paper ageing can be more accurately determined by controlling the water and oxygen during the experiment which then produced noticeable changes in predicting life expectancy. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
203. Streamlining the Inclusion of Computer Experiments In a Research Paper.
- Author
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Halle, Sylvain, Khoury, Raphael, and Awesso, Mewena
- Subjects
COMPUTER software reusability ,STREAMLINE moderne ,COMPUTER systems ,RESEARCH papers (Students) ,ELECTRONIC data processing - Abstract
Designing clean, reusable, and repeatable experiments for a research paper does not have to be difficult. We report on our efforts to create an integrated toolchain for running, processing, and including the results of computer experiments in scientific publications. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
204. The Importance of Power Quality Management in the Pulp and Paper Industry.
- Author
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Nacke, Bradford M. and Schlake, Randall L.
- Subjects
- *
ENERGY sources for pulp mills , *PAPER industry , *POWER supply of paper mills - Abstract
Identifies the common challenges in improving uptime for the pulp and paper plant engineer or industrial facilities manager. Power quality management concerns within the pulp and paper industry; Myths surrounding power conditioning and environmental protection in industrial settings; Power challenges to sensitive electronics in the industry; Kinds of equipment available to protect against power problems.
- Published
- 2002
- Full Text
- View/download PDF
205. Oxidation of Paper Insulation in Transformers.
- Author
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Ese, Marit-Helen Glomm, Liland, Knut B., and Lundgaard, Lars E.
- Subjects
- *
OXIDATION , *PAPER , *INSULATING oils , *ELECTRIC transformers , *POLYMERIZATION - Abstract
Oxidation ageing experiments on paper insulation and transformer oil have been performed using two different techniques. One is a traditional ageing study wherein degree of polymerization (DP) is measured after conditioning in sealed bottles containing paper submerged in oil, where the partial pressure of oxygen over the oil is varied. Paper is sampled at certain intervals during 8 months and DP-values are measured. The other study was carried out by means of a microcalorimeter; continuously measuring the heat flow from the paper-oil sample. We find that the degradation reaction rate is not linear with oxygen concentration and that the activation energy of oxidation is lower than what has earlier been found for hydrolysis. The microcalorimeter appears to mimic ageing characteristics for oxidation and can potentially be a useful tool for quick ageing investigations. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
206. On the Frequency Domain Dielectric Response of Oil-paper Insulation at Low Temperatures.
- Author
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Fofana, I., Hemmatjou, H., Meghnefi, F., Farzaneh, M., Setayeshmehr, A., Borsi, H., and Gockenbach, E.
- Subjects
- *
PAPER , *ELECTRIC insulators & insulation , *DIELECTRICS , *LOW temperatures , *SPECTRUM analysis , *ELECTRIC conductivity - Abstract
Results of Frequency Domain Spectroscopy measurements are known to be largely influenced by environmental conditions, such as the temperature. Because field measurements, last hours after de-energizing the transformer, the ambient temperature may affect the results. Especially in cold regions of the world, extreme care are required to interpret the results when performing tests at relatively low surrounding temperatures. A better understanding and analysis of the dielectric test results are therefore only possible with a clear understanding of the physical behavior of the insulation system in response to the ambient conditions. In this contribution, the dielectric behavior of a composite oil paper insulation system has been explained from the properties of Debye basic model. A series of experiments have been performed under controlled laboratory conditions with preset moisture content inside the insulation. The equivalent circuit parameters of a laboratory made oil paper condenser bushing model were obtained using a non-linear optimization procedure. Since the dielectric parameters values are geometry dependent, poles, calculated from resistances and capacitances, were used as they are independent of the geometry. It was shown that the poles can be regarded as parameters able to be used for insulation condition assessment. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
207. Experimental simulation of effects of high temperatures on paper oil insulation of transformers in presence of DBDS in mineral oil.
- Author
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Flora, S. Daisy, Thirumurthy, Meena, K. P., and Rajan, J. Sundara
- Subjects
DIBENZYL ketone ,KETONES ,THERMAL conductivity ,POLARIZATION (Electricity) ,COPPER sulfide - Abstract
The effect of elevated temperatures induced by over currents on the performance of paper oil insulation of transformer is investigated. This study has been carried out in presence of spiked concentrations of Dibenzyl disulphide (DBDS) in mineral oil for understanding its effects on copper sulphide formation. The dielectric response of paper oil insulation when subjected to elevated temperatures is studied using frequency domain spectroscopy and measurement of polarization and depolarization current. It is observed that there are significant variations in tan ? (dissipation factor) and magnitudes of polarization and depolarization currents of paper oil insulation due to high temperatures. A characteristic peak of tan ? around 0.1 Hz in the FDS response is observed to indicate the presence of copper sulphide on paper. A FEM based thermal model is proposed to explain the distribution of thermal conductivity and temperature gradient in paper oil insulation due to copper sulphide deposits. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
208. Improved Inversion Method for Multi-Regional Oil-Immersed Paper Resistivity in Transformer.
- Author
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Xie, Yiming, Ruan, Jiangjun, Huang, Daochun, Shi, Yu, Jin, Shuo, Deng, Yongqing, and Hu, Yuanchao
- Subjects
- *
POWER transformer insulation , *NEWTON-Raphson method , *BACK propagation , *POWER transformers , *INVERSE problems - Abstract
Oil-paper insulation ageing of transformer has characteristics of spatial locality due to uneven temperature distribution. The transformer is sealed, it is difficult to obtain the local ageing state of oil-paper insulation by sampling directly. Currently, there are no effective detection method to detect the insulation state of local regions. The oil-immersed paper resistivity inversion method can nondestructively assess the local state of oil-paper insulation. However, the current inversion methods still have shortcomings and need to be improved. In this paper, combining the back propagation neural network (BPNN) and Newton downhill method (NDM), an improved inversion method is proposed to optimize the current inversion method, so as to reduce the effect of initial value on it and make calculated results converge better. Finally, a 3D 10 kV transformer model is established to verify the effectiveness of the proposed method. The resistivity calculated by the improved method show that the method can provide initial resistivity values for technicians and improve the convergence and accuracy of current inversion method, which is more suitable for extending to the engineering practice. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
209. Integrated Control-Fluidic Codesign Methodology for Paper-Based Digital Microfluidic Biochips.
- Author
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Wang, Qin, Schlichtmann, Ulf, Cai, Yici, Ji, Weiqing, Li, Zeyan, Cheong, Haena, Kwon, Oh-Sun, Yao, Hailong, Ho, Tsung-Yi, Shin, Kwanwoo, and Li, Bing
- Subjects
- *
BIOCHIPS , *CONDUCTIVE ink , *CARBON nanotubes , *VOLTAGE control , *INK-jet printers , *FLUIDIC devices - Abstract
Paper-based digital microfluidic biochips (P-DMFBs) have recently emerged as a promising low-cost and fast-responsive platform for biochemical assays. In P-DMFBs, electrodes and control lines are printed on a piece of photograph paper using an inkjet printer and carbon nanotubes (CNTs) conductive ink. Compared with traditional digital microfluidic biochips (DMFBs), P-DMFBs enjoy significant advantages, such as faster in-place fabrication with printer and ink, lower costs, and better disposability. Since electrodes and CNT control lines are printed on the same side of this paper, a critical design challenge for P-DMFB is to prevent control interference between moving droplets and the voltages on CNT control lines. Control interference may result in unexpected droplet movements and thus incorrect assay outputs. To address this design challenge, a control-fluidic codesign methodology is proposed in this paper, along with two demonstrative design flows integrating both fluidic design and control design, i.e., the droplet-oriented codesign flow and the electrode-oriented codesign flow. The droplet-oriented flow is suitable for designing biochips with sparse electrodes and relatively larger number of droplets, whereas the electrode-oriented flow is suitable for biochips with dense electrodes and smaller number of droplets. The computational simulation results of real-life bioassays demonstrate the effectiveness of the proposed codesign flows. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
210. Effect of AC-voltage harmonics on oil impregnated paper in transformer bushings.
- Author
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Li, Shijun, Yang, Liuqing, Li, Shengtao, Zhu, Yuanwei, Cui, Huize, Yan, Wei, Ge, Zhao, and Abu-Siada, A.
- Subjects
- *
FOURIER transform spectroscopy , *RENEWABLE energy sources , *DIFFERENTIAL scanning calorimetry , *BUSHINGS , *THERMAL stresses , *POWER transformers , *PRECIPITATION hardening - Abstract
With the global trend to establish smart distributed-generation grids, the level of AC-voltage harmonics is significantly increasing due to power electronic converters interfacing renewable energy sources with the grid. Such harmonics will not only degrade the power quality and increase the losses in the electricity grids but will also have a severe impact on oil impregnated paper (OIP) in power transformer bushings. While much attention has been given to investigate the deterioration of OIP under thermal and electrical stresses, the impact of voltage harmonics on the OIP structure is still uncertain and calls for more investigations. Therefore, this paper is aimed at investigating the variations of the multilevel structure of an OIP aged under high levels of AC-voltage harmonics. In this context, degree of polymerization of the aged OIP is measured to reveal the changes of OIP secondary structure. Also, X-ray diffraction, deuteration treatment and Fourier transform infra-red spectroscopy are conducted to analyze the changes of the OIP aggregate structure during the aging process. Further experiments are performed to investigate the variation of the microscopic appearance, thermal behavior and dielectric properties, including scanning electronic microscopy, thermal gravity analysis, differential scanning calorimetry and frequency domain spectroscopy. This investigation on the variation of the multilevel structure of aged OIP not only promotes further understanding to the aging behavior and mechanism of OIP under AC-voltage harmonics, but also proposes crystallinity and accessibility as two new effective aging indicators for the OIP structure. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
211. Breakdown and streamer behavior in double-layer oil-paper insulation under impulses of varying front time.
- Author
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Ni, Heli, Zhang, Qiaogen, Guo, Chong, and Wen, Tao
- Subjects
- *
SPACE charge , *BREAKDOWN voltage , *HIGH voltages - Abstract
The breakdown and streamer behavior in double-layer oil-paper insulation under impulses of varying front time were investigated in this study to determine the prebreakdown process in oil-paper insulation. The relationships between front times and breakdown characteristics were investigated and impulse-polarity-dependent variations were observed. The complete impulse breakdown process and precise role of front time were assessed as per streamer initiation and streamer propagation based on emitted light signals and shadow images. The re-initiation of streamers in non-first oil gaps was determined to be the key factor in breakdown as-dominated by applied voltage and space charge accumulation. The initiation and propagation times of streamers were observed to find that the streamers tend to propagate at phases with higher voltage amplitude as front time increases, which facilitates streamer re-initiation and thus decreases the breakdown voltage. Equivalent applied voltages during streamer propagation were further calculated to quantitatively investigate the effect of front time on streamer propagation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
212. Wavelength-Switchable and Wavelength-Tunable All-Normal-Dispersion Mode-Locked Yb-Doped Fiber Laser Based on Single-Walled Carbon Nanotube Wall Paper Absorber
- Author
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Xiao-Hui Li, Yong-Gang Wang, Yi-Shan Wang, Xiao-Hong Hu, Wei Zhao, Xiang-Lian Liu, Jia Yu, Cun-Xiao Gao, Wei Zhang, Zhi Yang, Cheng Li, and De-Yuan Shen
- Subjects
Fiber lasers ,mode-locked lasers ,tunable lasers ,carbon nanotubes and confined systems ,Applied optics. Photonics ,TA1501-1820 ,Optics. Light ,QC350-467 - Abstract
We demonstrate a compact wavelength-tunable and -switchable mode-locked Yb-doped fiber (YDF) laser based on single-walled carbon nanotube (SWCNT) wall paper absorber. Two mechanisms coexist in the fiber cavity. The switchable mode-locked state can be obtained between two wavelengths depending on the fiber-loop-induced cavity birefringence. Because of the intensity-dependent transmission distribution, the proposed fiber laser can be operated in the tunable wavelength mode-locked state from 1025 to 1037 nm. The spectral bandwidth varied from 1.1 to 2.4 nm depending on the operating wavelength and the pump power with pulse duration of hundreds of picoseconds. The average wavelength spacing is 3.6 nm, which can be changed, corresponding to the birefringence of the fiber cavity. Moreover, stable wavelength-tunable mode locking is obtained at room temperature.
- Published
- 2012
- Full Text
- View/download PDF
213. Dielectric response and space charge in epoxy impregnated paper composite laminates.
- Author
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Wang, Qingyu, Peng, Zongren, Dodd, S. J., Dissado, L. A., and Chalashkanov, N. M.
- Subjects
- *
SPACE charge , *LAMINATED materials , *DIELECTRICS , *EPOXY resins , *DIELECTRIC properties , *THERMOPLASTIC composites - Abstract
As the main material of the converter transformer dry-type bushing, the dielectric properties of epoxy/crepe paper at different temperatures and frequencies are related to the electric field and thermal field distribution of the bushing, which directly affects the safe and stable operation of the bushing. Here we report the dielectric response of samples of dry-type bushing insulation measured at a range of temperatures appropriate to operation and down to frequencies below those usually used. A significant loss peak observed below power frequency is interpreted as originating from the charging of internal epoxy resin interfaces by the transport of charge carriers on structured paths in the epoxy-impregnated crepe paper layers. A simulation model is proposed that allows estimation of the space charge and field distribution at any given frequency. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
214. A comprehensive analyses of aging characteristics of oil-paper insulation system in HVDC converter transformers.
- Author
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Cui, Huize, Yang, Liuqing, Zhu, Yuanwei, Li, Shengtao, Abu-Siada, A., and Islam, Syed
- Subjects
- *
INSULATING oils , *ELECTRIC fields , *TRANSFORMER insulation , *THERMAL stresses , *BREAKDOWN voltage - Abstract
This paper investigates the dissolved gases evolution in transformer oil under combined DC/AC electrical-thermal stress. Dissolved gases detected in transformer aged insulation oil reveal that oil under AC electric field combined with thermal stress can produce more dissolved gases than oil under DC electric field with thermal stress but less than the gases produced in oil under distorted AC or combined AC/DC voltage stress. This is attributed to the divergent migration properties of the charged components under different types of electric fields. To further understand this behavior, carrier recombination coefficient is proposed to explain the oil DGA results under various aging stresses. Results show that diagnostic parameters such as breakdown voltage, oil interfacial tension, and moisture content in pressboard should be used along with DGA results in order to accurately diagnose the insulation condition within converter transformers that impose a combined AC/DC voltage stress on the insulation system. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
215. Mechanism and numerical model of bubble effect in oil-paper insulation based on microtubule model.
- Author
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Liu, Yunpeng, Chao, Nijie, Zhao, Tao, Tong, Yixin, and Jia, Chenhao
- Subjects
- *
BUBBLES , *IDEAL gases , *POWER transformers , *EQUATIONS of state , *PHYSICAL constants , *HEAVY oil - Abstract
In this paper, a numerical model of bubble evolution is established by studying the microstructure of pressboard and the physical process of bubble generation. In the model, the porous structure of fibers is equivalent to microtubules, the gases in the bubbles are classified into two categories, and the ideal gas state equation is used to describe the bubble state. Then the pressure conditions at the bubble boundary and the evaporation rate of water are taken as solution conditions to solve the physical quantities in the state equation. The numerical model provides a new way to calculate the initial temperature of bubble escape (ITBE). And the bubble evolution inside the pressboard is obtained which is hard to be observed in experiment. After that, the influences of moisture content of pressboard and cellulose aging on ITBE in the numerical model are discussed. The model results show that the expansion rate of bubble is not uniform. Bubble growth is slow in the early stage of temperature rise, when the temperature reaches a certain threshold the growth rate of bubble radius increases significantly, which is of great significance to the temperature limit on oil-immersed power transformers. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
216. A Motion-Planning Approach to Folding: From Paper Craft to Protein Folding.
- Author
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Guang Song and Amato, Nancy M.
- Subjects
- *
MOTION , *PAPER folding (Graphic design) , *TYPOGRAPHIC design , *PROTEIN folding , *AUTOMATION , *ROBOTICS - Abstract
In this paper, we present a framework for studying folding problems from a motion-planning perspective. The version of the motion-planning problem we consider is that of determining a sequence of motions to transform some configuration of a foldable object (the start) into another configuration (the goal). Modeling foldable objects as tree-like multilink objects allows us to apply motion-planning techniques for articulated objects with many degrees of freedom (many links) to folding problems. An important feature of this approach is that it not only allows us to study foldability questions, such as, can one object be folded (or unfolded) into another object, but it also provides us with another tool for investigating the dynamic folding process itself. The frame-work proposed here has application to traditional motion-planning areas such as automation and animation, to paper-folding problems studied in computational geometry, and to computational biology problems such as protein folding. Preliminary experimental results with paper folding and the folding of small proteins (approximately 60 residues) are quite encouraging. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
217. Load Recovery in the Pulp and Paper Industry Following a Disturbance.
- Author
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Agneholm, Evert and Daalder, Jaap E.
- Subjects
- *
PAPER industry , *ELECTRIC power failures - Abstract
Presents a study which dealt with the load behavior of pulp and paper industries after planned or forced outages. Description of a pulp and paper industry; Discussion on outages; Economical consequences.
- Published
- 2000
- Full Text
- View/download PDF
218. Interface charge behavior of multi-layer oil?paper insulation under DC and polarity reversal voltages.
- Author
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Du, B. X., Zhang, J. G., and Liu, D. S.
- Subjects
ELECTRIC insulators & insulation ,MULTILAYERS ,DIRECT currents ,ELECTRIC potential ,POWER transformers - Abstract
Transformer oil, insulating paper, high voltage direct current (HVDC) bushings and on-load tap changer (OLTC) are essential parts of converter transformers. When the power flow of the HVDC system is reversed or a sudden outrage occurs, the charge field will deform the dielectric internal electric field, thus easily leading to the occurrence of discharge or insulation damage. In this case, it is necessary to carry out the characterization of the oil?paper interface to avoid these consequences. This paper analyses the interface charge accumulation and dissipation characteristics of an oil?paper insulation system under DC and polarity reversal voltages. In this paper, induced electrification was used to charge the composite oil?paper insulation. The amplitude of DC and polarity reversal voltages applied in this paper was 4 kV, and paper with thicknesses of 0.08 and 0.13 mm was used. This research offers a theoretical exploration to optimize the transformer oil? paper insulation structure and prevent damage to its insulation systems. From the research on different layers and thicknesses of paper, it can be concluded that the decay is fast in the initial period and then becomes slower with the lapse of time until finally the decay curve tends to become flat. With an increase in the number of the paper layers, the interface charge density decreases. So in real life multilayer paper is used to avoid failures owing to its structural weakness. Regarding the DC polarity reversal effect, increasing the thickness of the paper is equivalent to adding paper layers. The dissipation rate of the positive interface charge is quicker than that of the negative one. In the polarity reversal test, the dissipation rate becomes smaller as the reversal time gets longer. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
219. Acids generated and influence on electrical lifetime of natural ester impregnated paper insulation.
- Author
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Yao, Wei, Li, Jian, Huang, Zhengyong, Li, Xiangrong, and Xiang, Chenmeng
- Subjects
ACID analysis ,INSULATING oils ,ESTERS ,HYDROLYSIS kinetics ,MEASUREMENT of viscosity - Abstract
Acids have attracted an increasing interest from researchers for the standard evaluation of transformer oil, especially in natural ester. This study aims to investigate the types of generated acids in natural ester under hydrolysis, oxidation, and accelerated thermal aging tests with varying paper moistures. The oxidation and hydrolysis degrees were evaluated by acid number and kinematic viscosity, and acids were distinguished from aging condition hydrolysis of oil paper insulation by combining pH values. Meanwhile, the electrical lifetime of oil-paper insulation with seven types of acid were analyzed by step-stress test. The two-parameter Weibull distribution was used to analyze the mean lifetime of specimens statistically. Experimental results reveal that the majority of acids generated from hydrolysis and the main acids are long-chain fatty acids of natural ester impregnated paper insulation. Furthermore, the electrical lifetime models of oil-paper insulation with different types acid were established, and the voltage endurance coefficient with seven types of acids were also obtained. The electrical lifetime test indicated that acids can reduce the electrical lifetime of natural ester impregnated paper insulation and that the effect of low-molecular-weight acids on insulation lifetime is approximately 2–3 times higher than high-molecular-weight acids. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
220. Furfural Analysis for Assessing Degradation of Thermally Upgraded Papers in Transformer Insulation.
- Author
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Morais, R.M. and Mannheimer, W.A.
- Subjects
ELECTRIC transformers ,PAPER in electrical insulation ,INSULATING paper - Abstract
Provides information on a study that explored the furfural analysis for assessing degradation of thermally upgraded papers in transformer insulation. Thermal aging of insulating papers; Experimental procedures; Description of insulating papers; Conclusions.
- Published
- 1999
- Full Text
- View/download PDF
221. Ageing rate of paper insulation used in power transformers Part 2: Oil/paper system with medium and high oxygen concentration.
- Author
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Lelekakis, Nick, Martin, Daniel, and Wijaya, Jaury
- Subjects
ELECTRIC transformers ,OXYGEN ,ELECTRICAL engineers ,RELIABILITY in engineering ,INSULATING oils ,HYDROLYSIS ,TEMPERATURE measurements - Abstract
Utility asset managers and engineers are concerned about the life and reliability of their power transformers which depends on the continued life of the paper insulation. The ageing rate of the paper is affected by water, oxygen and acids. Traditionally, the ageing rate of paper has been studied in sealed vessels however this approach does not allow the possibility to assess the affect of oxygen on paper with different water content. The ageing rate of paper has been studied for dry paper in air (excess oxygen). In these experiments we studied the ageing rate of Kraft and thermally upgraded Kraft paper in medium and high oxygen with varying water content. Furthermore, the oxygen content of the oil in sealed vessels is low which represents only sealed transformers. The ageing rate of the paper has not been determined for free breathing transformers with medium or high oxygen content and for different wetness of paper. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the ageing rate of paper with the same water content increased with oxygen content in the oil. Hence, new life curves were developed based on the water content of the paper and the oxygen content of the oil. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
222. Breakdown and Partial Discharge Characteristics of Transformer Board and Insulating Paper Materials in Liquid Nitrogen.
- Author
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Garzem, Michael, Grunwald, Marcel, Schnorrenberg, René, Schumacher, Ralph, and Humpert, Christof
- Subjects
- *
PARTIAL discharges , *TRANSFORMER insulation , *ELECTRIC insulators & insulation , *INSULATING materials , *POLYIMIDES - Abstract
Breakdown (BD) and partial discharge (PD) characteristics of insulating paper and transformer board materials are investigated as cost-effective alternatives to high-price materials like polyimide (PI) or polytetrafluoroethylene and fiber reinforced plastic materials typically used in superconducting devices based on high temperature superconductors cooled with liquid nitrogen (LN2). Three different cotton and cellulose based insulating papers are tested in LN2 at atmospheric pressure and compared to synthetic sheet materials and polypropylene laminated paper (PPLP). Additionally, the BD performance and PD characteristics of three different transformer board materials are investigated in LN2 . The results reveal that the paper and board materials have nearly the same or even slightly higher BD voltages in LN2 in comparison to the values in insulating oil. The pure paper materials with thicknesses of 130 μm have a dielectric strength of 70-90 kV/mm, whereas values of 130-140 kV/mm are measured for PPLP and PI with nearly the same thickness. The dielectric strength of the board materials has a maximum value of 76 kV/mm. In the frame of the investigations, the BD performance of the pure paper materials in LN2 is not influenced by the water content of the materials, dried and undried specimens have nearly the same BD voltage. Only the PPLP material has a 15% higher BD voltage in the dried state in comparison to the undried state. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
223. Investigation into degradation properties of low-viscosity silicone liquid/paper insulation systems for diagnosis in liquid-immersed transformers.
- Author
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Morooka, Hisashi, Yamagishi, Akira, Miyahara, Hideyuki, and Sampei, Hiroyuki
- Subjects
SILICONES ,ELECTRIC insulators & insulation ,ELECTRIC transformers ,VISCOSITY ,RELIABILITY in engineering ,TENSILE strength - Abstract
Thermal and electrical degradation properties in low-viscosity (20 mm2/s, (20 cSt) at 25 °C) silicone liquid and insulation paper were investigated to improve reliability and to enable preventive maintenance technology in transformers. Heat-accelerated degradation in samples of 20 cSt silicone liquid and insulation paper in sealed glass tubes with copper, silicon steel, and pressboard was examined to replicate the environment of the transformer tank. After the examinations, the tensile strength of the paper was measured, and the quantity of decomposition compounds was also measured. It was concluded that diagnosing faults by analyzing decomposition compounds with silicone liquid should be possible in the same way that it is with conventional mineral oil. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
224. On the experimental determination of the nitrogen content of thermally upgraded electrical papers.
- Author
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Rodriguez, Esperanza, Jalbert, Jocelyn, Duchesne, Steve, Arroyo, Oscar H., Rodriguez, Lidia, Cross, James, and Lewand, Lance
- Subjects
ENERGY consumption ,NITROGEN content of metals ,REPRODUCIBLE research ,NITROGEN content of algae ,ELECTRIC conductivity - Abstract
In this paper, the nature of thermally upgraded Kraft electrical insulating papers and their characterization by measurement of nitrogen content is discussed. A historical context and explanation of the basics of the various chemical methods used to measure nitrogen content in electrical papers is presented. The Kjeldahl and Dumas methods for quantifying nitrogen content were compared using six insulating papers in different laboratories in an effort to correlate the results obtained with both techniques. The results provide an insight into the viability of the Dumas combustion method as a proposed industry standard test for measuring the nitrogen content of paper. Moreover, data on the accuracy, reproducibility, and repeatability of the Dumas method is provided for the analysis of thermally upgraded electrical papers. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
225. Guest Editorial: Special Issue Based on Papers Submitted to All 2018 IEEE TEMS Conferences.
- Author
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Quan, Xiaohong Iris and von Zedtwitz, Max
- Subjects
- *
TECHNOLOGY conferences , *ACQUISITION of manuscripts , *TECHNOLOGY management , *ENGINEERING management , *CONFERENCES & conventions - Abstract
The papers in this special issue were submitted to all the conferences organized by IEEE Technology and Engineering Management Society (TEMS) in a given calendar year. In 2017, IEEE TEMS initiated its flagship conference TEMSCON (held in Silicon Valley), which serves as rebranding from its original International Technology Management Conferences (ITMC). Following that, in 2018, two more conferences were initiated globally, one in Asia known as IEEE TEMS International Symposium on Innovation and Entrepreneurship (ISIE), and one in Europe as IEEE TEMS International Conference on Technology and Entrepreneurship (ICTE). For this special issue, we invited authors attending any of the three aforementioned conferences in 2018 to submit full manuscripts for reviews, and the present special issue with eleven papers is the result of a careful selection following our usual rigid double-blinded peer-review process. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
226. Characterization of water-participant hydrogen bonds in oil-paper insulation investigated with terahertz dielectric spectroscopy.
- Author
-
Wang, Hanqing, Cheng, Li, Cheng, Zhidong, Yin, Jing, Yang, Lijun, and Liao, Ruijin
- Subjects
- *
TERAHERTZ spectroscopy , *HYDROGEN bonding , *NONDESTRUCTIVE testing , *PERMITTIVITY , *PERSUASION (Rhetoric) - Abstract
In this study, aiming to characterize the dynamic polarization behavior of water molecules affected by hydrogen bonding with oil-paper insulation, we performed dielectric spectroscopy on oil-paper insulation with moisture contents of 0.4–4.7% in the terahertz band (0.3–3.3 THz). A relaxation-resonance integrated polarization model considering water-participant hydrogen bond (WHB) effects is established to describe the complex dielectric constant of oil-paper insulation with moisture. The theoretical model is in good agreement with the experimental results. By analyzing the relationship between the polarization parameters and moisture content, three states of WHBs are found. The WHB type, strength and disorder show different characteristics with increased moisture. Furthermore, molecular simulation studies are carried out, and the calculation results provided a persuasive argument for the analysis of terahertz dielectric spectroscopy. This research reveals an important new strategy for studying the polarization behavior of water molecules affected by oil-paper insulation as an experimental supplement to molecular simulation. The proposed test and analysis method render effective and sustainable progress in practical applications of rapid nondestructive evaluation and 2D imaging of moisture content distributed in oil-paper insulation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
227. Dielectric modeling of oil-paper insulation systems at high DC voltage stress using a charge-carrier-based approach.
- Author
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Gabler, Tobias, Backhaus, Karsten, Grosmann, Steffen, and Fritsche, Ronny
- Subjects
- *
HIGH voltages , *DIELECTRICS , *ELECTRIC field effects , *ELECTRIC conductivity , *ELECTRIC insulators & insulation , *POISSON'S equation - Abstract
It is state-of-the-art to describe the dielectric behavior of an insulation material by its permittivity and its specific electric conductivity in order to estimate the dielectric stress of an insulation system. Thus, the electric field at DC voltage stress is determined according to the stationary electrical conduction field with the electric conductivity of the insulation materials. However, at oil-insulated arrangements a higher field strength in front of bare metal electrodes at high DC voltage stress occurs, which is not explainable with this model. Therefore, a charge carrier-based approach is presented to describe the dielectric behavior of the oil-paper insulation. It describes the movement of charge carriers and their effect on the electric field strength. Their drift leads to an accumulation of charge carriers in front of electrodes which results in a higher field strength in these areas, which can be calculated numerically using the Poisson-Nernst-Planck equation system. Compared to the conductivity-based model fundamental differences can be shown. Breakdown experiments qualitatively confirm the expectations according to the charge carrier-based approach. The results show that the charge carrier-based field distribution has to be considered for modelling the electrical field strength distribution at high DC voltage stress. They also show, that the dielectric behavior of these arrangements cannot be explained according to the state-of-the-art model. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
228. Analysis of Recovery Voltage Parameters of Paper-Oil Insulation Obtained from Simulation Investigations Using the Cole-Cole Model.
- Author
-
Wolny, S. and Zdanowski, M.
- Subjects
- *
INSULATING oils , *PAPER in electrical insulation , *COMPUTER simulation , *ELECTRIC potential , *ELECTRIC power transmission , *DIELECTRICS - Abstract
The paper presents the application of the Cole-Cole model for determining the runs of the return voltage of the paper-oil insulation sample through a computer simulation. Different insulation conditions were simulated through an adequate selection of parameters a and T of the Cole-Cole model. For calculation purposes, a series - parallel substitute scheme, obtained through approximation of discrete characteristic operator impedance Za of the model applied, was used. The diagnostics of the simulated insulation condition was based on the analysis of a few selected parameters of the return voltage, obtained from time characteristics. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
229. Dielectric frequency response of oil-impregnated paper: The effect of partial discharges compared to other influences.
- Author
-
Niasar, M. Ghaffarian, Taylor, N., Edin, H., and Kiiza, R. Clemence
- Subjects
- *
DIELECTRICS , *FREQUENCY response , *PAPER , *PARTIAL discharges , *ELECTRODES , *ELECTRIC conductivity - Abstract
In this paper, the influence of partial discharges (PD) on the subsequent dielectric properties of oil-impregnated paper (OIP) is investigated. Dielectric frequency response (DFR) of OIP is investigated at varied levels of moisture, thermal aging, temperature, oil conductivity and electrode material, to allow comparison of these influences. It is shown that PD activity inside OIP can significantly change the real and imaginary parts of permittivity of the paper layers, especially in the frequency range below 100 Hz. It is shown that even if the PD activity is concentrated on a few percent of the test sample, the real part of permittivity measured on the entire sample after a few tens of hours of PD activity can increase up to 10 times at very low frequencies (∼ 1 mHz) and the imaginary part of the permittivity can increase up to 100 times at low frequencies (∼ 1 Hz). The change of the real and imaginary parts of permittivity due to PD activity is permanent. It is very similar to the change caused by thermal aging, and somewhat similar to the change caused by moisture and higher oil conductivity. It is also shown that the dissipation factor of OIP in contact with copper and brass increases, even in the absence of PD, but contact with aluminum and stainless steel has no influence on DFR of OIP. The results suggest that the influence of PD can be significant when estimating the moisture content or the level of thermal aging of OIP with DFR method. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
230. Adequacy of dual-variable Weibull failure distribution for oil-impregnated paper under pulsating DC voltage.
- Author
-
Li, Jian, Bao, Lianwei, Zhang, Jing, and Li, Xudong
- Subjects
- *
PULSATION (Electronics) , *WEIBULL distribution , *PAPER , *DIRECT currents , *ELECTRIC potential , *FAILURE analysis - Abstract
This paper presents an experimental work investigating the failure data of oil-impregnated paper under pulsating DC voltage. The failure data of the oil-impregnated paper specimens were obtained through constant voltage stress tests; the Weibull distribution was used to estimate the statistical distribution of failure data. The exponential function (EF) and the inverse power function (IPF) were used to modify the Weibull distribution of failure data, so as to obtain two dual-variable Weibull failure distributions (WFDs), which were used to analyze failure data of oil-paper specimens obtained under pulsating DC and individual DC and AC voltages. Their adequacies were evaluated by using failure data obtained through the constant stress tests under various voltages. Both EF-modified and IPF-modified WFDs show more adequacy for failure data of oil-paper insulation under DC and pulsating DC voltages than AC voltages. The EF-modified WFD was more adequate than IPF-modified WFD in estimating the statistical distribution of failure data. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
231. Influences of temperature on partial discharge behavior in oil-paper bounded gas cavity under pulsating DC voltage.
- Author
-
Bao, Lianwei, Li, Jian, Zhang, Jing, Li, Xin, and Li, Xudong
- Subjects
- *
PARTIAL discharges , *ELECTRIC insulators & insulation , *PAPER , *TEMPERATURE effect , *PULSATION (Electronics) , *ELECTRIC potential - Abstract
The oil-paper insulation of valve-side windings in a high voltage direct current (HVDC) converter transformer is subjected to both complicated voltage and severe thermal stresses. Partial discharge (PD) occurring in oil-paper bounded cavities is influenced by voltage stress type as well as temperature. This paper presents PD behaviors in an oil-paper bounded gas cavity under pulsating DC voltages. The voltage across the gas cavity and PD inception voltages at different test conditions are analyzed. Influences of temperature on statistical PD distributions and parameters are also presented. A numerical model is used to interpret PD behaviors under pulsating DC voltages and various temperatures. Experimental results and theoretical statements show that the temperature exhibits a great influence on the behaviors of cavity discharge under pulsating DC voltages. Volume resistivity, gas pressure, charge decay time constant, and electron generation rate are the primary parameters influencing PD behaviors at different temperatures. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
232. Modeling of Transient Moisture Equilibrium in Oil-paper Insulation.
- Author
-
Zhou, L. J., Wu, G. N., and Liu, J.
- Subjects
INSULATING oils ,MINERAL oils ,ELECTRIC transients ,ELECTRIC currents ,TEMPERATURE - Abstract
This paper introduces a new model for transient moisture equilibrium in oil-paper insulation, easily applicable even in a continuous way, based on Fick's second law. According to the model, the moisture concentration in paper follows step response function, but the equilibration time constant changes with time since it depends on temperature, paper thickness, equilibration moisture in oil-paper insulation, and number of oil-paper interfaces. The model is validated against experimental data. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
233. Partial discharge characteristics and trap parameters of aged oil-impregnated paper.
- Author
-
Wei, Yan-Hui, Zhu, Ming-Xiao, Li, Yuan, Zhao, Lin, Deng, Jun-Bo, Mu, Hai-Bao, and Zhang, Guan-Jun
- Subjects
PARTIAL discharges ,PARAMETERS (Statistics) ,INSULATING oils ,PAPER ,THERMALLY stimulated currents ,ELECTRIC transformers ,POLYMERIZATION - Abstract
The degradation of oil-impregnated paper induced by partial discharge (PD) seriously affects the life of power equipment. In order to investigate the relationship between partial discharge and the degradation of oil-impregnated paper, PD characteristics and trap parameters of the impregnated paper are measured. In this work, a cavity discharge model is adopted and samples with different degrees of polymerization (DP) are fabricated using thermally accelerated aging to simulate transformers with different lifetimes. For each sample, phase resolved partial discharge (PRPD) spectrograms are recorded for various partial discharge times. The characteristics of partial discharge are analyzed, and the trap parameters of specimens are obtained by the thermally stimulated depolarization current (TSDC) method. Following this, the microstructures of the samples are observed using a scanning electron microscope (SEM). It is found that the damaging breakdown process of oil-immersed paper can be divided into three stages: initial stage, developing stage and pre-breakdown stage. There also exist two levels of trap on the surface of oil-impregnated paper: shallow (0.10-0.59 eV) and relatively deep (0.60-0.90 eV) energy. Importantly, the thermal aging makes the trap energy deeper while electrical aging makes the trap energy shallower. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
234. Inkjet Printed Flexible Dual-Band Dual-Sense Circularly Polarized Patch Antenna
- Author
-
Abdul Rakib Hossain, Md. Samiul Islam Sagar, Aleks Aleksandrovich Mertvyy, Praveen Kumar Sekhar, and Tutku Karacolak
- Subjects
PET paper ,dual-band dual-sense ,circular polarization ,inkjet printer ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
This research proposes an inkjet printed dual-band dual-sense circularly polarized antenna using CPW-feeding on PET substrate. The antenna is designed and optimized using ANSYS HFSS, which operates at 4.01 GHz - 5.05 GHz (22.96%) and 6.23 GHz - 7.58 GHz (19.55%) with a return loss of $0.44\lambda $ x $0.52\lambda $ x $0.002\lambda $ , where $\lambda $ is the free-space wavelength at the lowest circular polarization frequency. Measurement of the fabricated version shows good agreement with the simulated version. To the best of author’s knowledge, this proposed design is the first circularly polarized antenna integrating flexibility with dual-band and dual-sensing characteristics.
- Published
- 2024
- Full Text
- View/download PDF
235. A new method for carrier mobility measurement in oil immersed cellulose paper insulation.
- Author
-
Cheng, Chuanhui, Wu, Kai, Su, Rui, Wu, Yang, and Dai, Jie
- Subjects
- *
ELECTRIC insulators & insulation , *ELECTRIC fields , *ELECTRODES , *ELECTRIC conductivity , *CHARGE transfer - Abstract
This paper reports on a new method to measure the mobilities of both positive and negative charges in insulating materials based on space charge measurement in two-layer samples. To fulfill the condition of a unipolar carrier system, a blocking material is used as a barrier on one electrode thereby preventing charge injection to ensure the unipolar charges injected from the other electrode are transported through the bulk and accumulate at the barrier. Experimentally, the carrier mobility of oil immersed cellulose paper was obtained using the proposed method, and the result of mobilities of both positive and negative charges is presented. The temperature and field dependence of carrier mobility were also investigated, and the activation energies for negative and positive charges were calculated. The obtained carrier mobility of negative charges (majority electron carriers) is approximately 2 times of that of positive charges, and the charge migration can be interpreted by the thermally activated hopping conduction mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
236. Motor Temperature Considerations for Pulp and Paper Mill Applications.
- Author
-
Albers, Timothy and Bonnett, Austin H.
- Subjects
- *
PAPER mills , *THERMAL analysis , *ROTORS , *SQUIRREL cage motors - Abstract
Provides information on a study concerning the effect of motor temperature on pulp and paper mill applications. Functions of enclosed fan and weather protected motors; Information on the thermal impact on stator winding rotor; Observation on the processes of squirrel-cage induction motors.
- Published
- 2002
- Full Text
- View/download PDF
237. Aging characterization of electrical insulation papers impregnated with synthetic ester and mineral oil: Correlations between mechanical properties, depolymerization and some chemical markers.
- Author
-
Fernandez, Oscar H. Arroyo, Fofana, Issouf, Jalbert, Jocelyn, Gagnon, Sylvie, Rodriguez-Celis, Esperanza, Duchesne, Steve, and Ryadi, Mohamed
- Subjects
ELECTRIC insulators & insulation ,ESTERS ,CHEMICAL synthesis ,MINERAL oils ,DEPOLYMERIZATION ,MECHANICAL behavior of materials ,THERMAL analysis - Abstract
This article presents a comparative study of two types of transformer solid insulation: standard Kraft and thermally upgraded Kraft papers. The paper samples were impregnated with two different fluids, namely a synthetic dielectric ester fluid, Midel 7131, and a synthesized mineral oil, Luminol Tri. The impregnated papers were submitted to, accelerated aging at 150°C, temperature higher than the temperatures found inside transformers, for extended periods. The results show that for the first hours of aging, the cellulose depolymerization was similar for all the four studied cases. At a specific point, the paper samples aged in the ester fluid exhibited a lower depolymerization exceeding the 8000 hours of aging without reaching the levelling-off degree of polymerization (LODP). A similar trend was observed through the decrease of mechanical properties of papers in the ester-based oil. However, the difference in performance of both fluids was amplified due to the temperature used; at lower temperatures the difference should be smaller. Additionally, a relationship between the degree of polymerization and the mechanical properties accessed by the tensile testing was obtained regardless of the type of paper or oil. The total acidity in the ester fluid was higher than in mineral oil. Methanol, a chemical marker that is closely linked to the rupture of 1,4-ß-glycosidic bonds of cellulose, showed a partial sensitivity to the cellulose aging in the ester fluid. Furan (C4H4O) content was monitored during the aging and its concentration was found to be sensitive to the depolymerization along with the decrease in the mechanical properties of cellulose papers regardless of the type of paper. More importantly, its concentration was found to be dependent on the type of oil. More investigations are needed to further confirm the importance of furan as an indirect indicator of the mechanical performance along with its correlation with the depolymerization of paper aged in ester fluids. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
238. The Dielectric Strength of Nomex 410 Paper in Liquid Nitrogen Under Boiling Situations.
- Author
-
Jin, Zhiyang, Lapthorn, Andrew, and Staines, Mike
- Subjects
ELECTRIC conductivity ,ELECTRIC resistors ,LIQUID nitrogen ,SUPERCONDUCTORS ,MAGNETIC fields ,ANISOTROPY - Abstract
It is crucial for the successful application of high-temperature superconducting (HTS) power transformers that they are able to survive under abnormal operations, such as a short-circuit fault. Modeling, based on the design of a four-winding three-phase HTS power transformer, suggests severe boiling will occur on the surface of the winding during a short-circuit fault and will jeopardize the turn-to-turn insulation of the HTS power transformer. In this paper, a turn-to-turn insulation breakdown experiment platform involving the introduction of boiling on the surface of electrode has been built. Nomex 410 paper, one of the candidates for turn-to-turn insulation in the design of the HTS power transformer, was tested. The characteristics of dielectric strength of Nomex 410 in three different thicknesses (0.13, 0.18, and 0.25 mm) have been investigated, without boiling, as well as under different boiling situations, in an open bath of liquid nitrogen. The voltage application methods applied during both experiments test the electrical breakdown of Nomex 410 under a dynamic situation. The experiment results show that when under film boiling, compared to the test results for nucleate boiling, the dielectric strength of Nomex 410 paper decreases by approximately 38% of the value when no boiling is involved. Moreover, it is verified that the presence of an electric field accelerates the heat transfer between the liquid nitrogen and the heated electrode. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
239. Assessment of paper-oil insulation under copper corrosion using polarization and depolarization current measurements.
- Author
-
Daisy Flora, S. and Rajan, J. Sundara
- Subjects
ELECTRIC insulators & insulation ,COPPER corrosion ,POLARIZATION (Electricity) ,PAPER ,ELECTRIC current measurement ,ELECTRIC circuits - Abstract
This paper discusses the effect of temperature on polarization and depolarization current measurements on paper oil insulation system. The influence of copper sulphide formed due to corrosive sulphur in mineral oil, on the changes in polarization and depolarization current at different temperatures are considered. A significant increase in the magnitude of polarization and depolarization currents due to deposits of copper sulphide on paper layers is observed. The conductivity of paper insulation increases significantly with increase in temperature. The increase in current is attributed to thermally active conducting particles of copper sulphide. The Debye model parameters of equivalent circuit under copper corrosion have been computed and a model for failure due to copper sulphide is explained using the data on polarization and depolarization currents. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
240. Impact of the Use of Vegetable Oil on the Mechanical Failure of the Cellulosic Insulation of Continuously Transposed Conductors in Power Transformers.
- Author
-
Oria, C., Mendez, C., Carrascal, I., Ortiz, A., and Ferreno, D.
- Subjects
MECHANICAL failures ,POWER transformers ,SERVICE life ,LIQUID dielectrics ,DEGREE of polymerization ,MINERAL oils ,ELECTRIC insulators & insulation ,VEGETABLE oils - Abstract
Natural esters have become of interest for the industry in recent years as dielectric liquids for power transformers, and many studies are focused on their dielectric and chemical properties and on their influence in the degradation of the solid insulation due to aging. However, very little is known about their impact on the evolution of the mechanical properties of the paper insulation, which are acknowledged to have a considerable influence in their overall performance and reliability during the operating life of power transformers. This work studies the effects of thermal aging with vegetable oil in some commercial components, which are commonly used in power transformers, such as an insulated continuously transposed conductor (CTC) and samples of thermally upgraded crepe insulation. The changes in the properties of the crepe paper insulation are characterized through the degree of polymerization and tensile testing. Failure initiation and propagation in the insulation of the CTC is analyzed macroscopically. The results are compared with those obtained when using mineral oil, showing that the use of vegetable oil has a protective effect over mechanical properties of the studied types of paper insulation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
241. Recognition of 2019 Transactions and Magazine Paper Reviewers.
- Author
-
Nondahl, Thomas A.
- Subjects
- *
PERIODICAL publishing , *TECHNICAL textiles - Abstract
Special Feature that lists the names of people involved in the review of technical papers for the IEEE Transactions on Industry Applications and Industry Applications Magazine. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
242. Cold High-Frequency Plasma Versus Afterglow Plasma in the Preservation of Mobile Cultural Heritage on Paper Substrate.
- Author
-
Rusu, Dorina E., Stratulat, Lacramioara, Ioanid, Ghiocel E., and Vlad, A. M.
- Subjects
- *
LOW temperature plasmas , *CULTURAL property , *CULTURAL maintenance , *PLASMA focus , *GAMMA ray bursts , *GASWORKS , *DECONTAMINATION (From gases, chemicals, etc.) - Abstract
This article presents a comparison between the results obtained at the application of a conservation treatment in cold high-frequency (HF) and afterglow plasma on historical papers dating in the 19th century. This article is focused on plasma biocide effects and on the impact of active species from the two types of plasma on the surface, highlighted by mechanical and physical–chemical analyses. The working gas was nitrogen and the treatment time was varied from 5 to 10 and 15 min. The result of physical–chemical analyses as SEM, pH determination, color, and tensile strength analyses, as well as microbiological investigations, converges to the conclusion that a treatment of 10 min achieves a complete decontamination, and the impact of active species is less intense in the afterglow plasma as compared to the direct discharge in cold HF plasma. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
243. Call for Papers: ISTAS24.
- Subjects
- *
DIGITAL Object Identifiers , *LICENSE agreements - Abstract
The article announces the IEEE International Symposium on Technology and Society, scheduled from September 18-20 in Puebla, Mexico, focusing on the Social Implications of Artificial Intelligence (AI), inviting submissions from academia, industry, and government to explore AI's impacts.
- Published
- 2024
- Full Text
- View/download PDF
244. Call for Papers for IEEE Transactions on Materials for Electron Devices.
- Subjects
- *
ELECTRONS , *DIGITAL Object Identifiers , *LICENSE agreements , *SEMICONDUCTOR manufacturing - Published
- 2024
- Full Text
- View/download PDF
245. Joint Call for Papers for IEEE Transactions on Semiconductor Manufacturing and IEEE Transactions on Electron Devices: Special Issue on Semiconductor Design for Manufacturing (DFM).
- Subjects
- *
SEMICONDUCTOR design , *SEMICONDUCTOR manufacturing , *ELECTRONS , *DIGITAL Object Identifiers - Published
- 2024
- Full Text
- View/download PDF
246. Neural network model for paper-forming process.
- Author
-
Scharcanski, Jacob and Dodson, C.T.J.
- Subjects
- *
PAPER industry , *ARTIFICIAL neural networks - Abstract
Presents an approach to the controllable simulation of paper forming using artificial neural network methods. Problem of simulating the dynamics of paper forming; Model for simulation of the dynamics of paper forming; Artificial neural networks and simulation of paper forming; Experimental results of the study; Discussion of the results; Conclusions.
- Published
- 1997
- Full Text
- View/download PDF
247. Experiments of Paper Insulation in a Corona Environment.
- Author
-
Lee, T. S., Fung, Bill K., and Zang Ming
- Subjects
- *
CORONA discharge , *INSULATING paper , *ELECTRIC breakdown - Abstract
Presents experimental findings on the effects of paper dielectric in a variety of corona environments. Observations on a single-sheet barrier as the applied voltage is increased from zero; Similarities and differences in using double-sheet barrier; Breakdown strength of gap.
- Published
- 2001
- Full Text
- View/download PDF
248. Low-Voltage Oxide-Based TFTs Self-Assembled on Paper Substrates With Tunable Threshold Voltage.
- Author
-
Sun, Jia, Jiang, Jie, Lu, Aixia, Dou, Wei, Zhou, Bin, and Wan, Qing
- Subjects
THIN film transistors ,THRESHOLD voltage ,LOW voltage systems ,ELECTRONIC modulation ,ELECTRODES ,PAPER - Abstract
Oxide-based thin-film transistors (TFTs) with a lateral in-plane electrode are self-assembled on paper substrates, and the electrical modulation effect of the in-plane electrode is investigated. A \SiO2-based solid-electrolyte film with high specific capacitance is used as the gate dielectric, and the operation voltage is reduced to less than 2.0 V. The threshold voltage (Vth) of such paper TFTs is tuned from -0.98 to 0.94 V by different voltage biases on the in-plane electrode. The threshold voltage shift (\Delta Vth) can be described by \Delta Vth = -(CG2/CG1)VG2, where CG2 and CG1 are the in-plane electrode and bottom-gate specific capacitance values. High electrical performance with a current on/off ratio of \6 \times \10^5 \sim \10^6, a subthreshold swing of 0.14 \sim 0.19 V/dec, and a mobility of \8.64 \sim \9.45\ \cm^2/\V\cdot \s is obtained at different in-plane electrode voltage biases. Such low-voltage paper TFTs are promising for low-cost and portable electronics. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
249. Features of an IEEE Communications Magazine Paper.
- Author
-
El-Bawab, Tarek S.
- Subjects
PERIODICAL editors ,CONFERENCE papers ,USER-generated content ,ELECTRONIC journals - Abstract
Our community publishes peer-reviewed journal, magazine, and conference papers and articles sharing a commitment to originality and to quality content and writing. These papers vary in their characteristics and style, depending on their objectives and their targeted readership. The IEEE Publication Services and Products Board (PSPB) Operations Manual (OM) also provides guidelines differentiating these paper types. There is confusion sometimes, however, concerning the features of magazine papers in particular. Some authors, especially early-career authors, do not fully appreciate certain differences between magazine papers and their journal, transaction, and letter counterparts. This can create a challenge for magazine editors and may result in delay, or rejection, of papers that could have been accepted if written with a better understanding of what magazines are about. We focus our attention here on this issue as it applies to IEEE Communications Magazine (ComMag) in particular. Our goal is to help our new and/or young authors who want to publish in ComMag to customize their writing to the nature of this magazine and enable them to author papers with higher chances of acceptance. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
250. Effect of temperature on space charge characteristics of oil-paper insulation and its numerical simulation.
- Author
-
Zhang, Jinfeng, Chen, Qingguo, Chi, Minghe, Tan, Peng, Sun, Wenxin, and Cao, Jinming
- Subjects
- *
SPACE charge , *TEMPERATURE effect , *COMPUTER simulation , *HEAVY oil - Abstract
In this study, the space charge in oil-impregnated thick pressboard and Kraft paper were measured by the pulsed electroacoustic (PEA) method from -20 to +60 °C. A bipolar charge transport model was used to simulate the transport processes of homocharge and heterocharge, and the acoustic attenuation process in the samples. The test results show that space charge accumulates in the thick pressboard and Kraft paper increases first and then decreases with temperature, and its maximum appears at 40°C, while little space charge accumulates at -20°C. The space charge near the lower electrode shrinks in the oil-impregnated thick pressboard at high temperature and the shrinkage is larger at 60°C. In the oil-impregnated Kraft paper, the accumulation and charge density of positive charge is different from negative charge. The ion transport process model simulates the charge shrinkage near the electrode, and disappears at the upper electrode after the acoustic attenuation simulation. The model established in this paper can well simulate the space charge distribution of oil-impregnated thick pressboard and Kraft paper under different temperatures. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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