2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena最新文献

{"title":"Comparison of Dielectric Properties of Low-density Polyethylene/MgO Composites with Different Size Fillers","authors":"K. Ishimoto, T. Tanaka, Y. Ohki, Y. Sekiguchi, Y. Murata, M. Gosyowaki","doi":"10.1109/CEIDP.2008.4772819","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772819","url":null,"abstract":"Two kinds of low-density polyethylene (LDPE) composites were prepared by adding semi-spherical MgO fillers different in diameter, one being around several ten nm and the other being several mum, and their dielectric properties were compared. At all the measurement temperatures, the conductivity is decreased and the permittivity is increased by the addition of fillers, irrespective of their sizes. However, the conductivity decrease is more significant and the permittivity increase is suppressed more in the case of the nm fillers. In addition, a drastic increase in dielectric loss factor at low frequencies is suppressed more significantly by the addition of the nm fillers. While the formation of packet-like charge observed in LDPE, which is assumed to appear at the front of the high-conductivity region that proceeds from one electrode toward the counter one, is suppressed significantly by both fillers, the effect is more significant in the nanocomposites. This means that the nanofillers suppress the increase in conductivity induced by the voltage application more effectively.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"148 1","pages":"208-211"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83470326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced Performance of Tree Initiation V-t Characteristics of Epoxy/Clay Nanocomposite in Comparison with Neat Epoxy Resin","authors":"S. Raetzke, Y. Ohki, T. Imai, J. Kindersberger, T. Tanaka","doi":"10.1109/CEIDP.2008.4772803","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772803","url":null,"abstract":"Tree initiation behavior of an epoxy nanocomposite with 5 wt % nanoclay (layered silicate) was investigated in comparison to neat epoxy resin without fillers. To shorten the time for experiments, 600 Hz was used instead of 60 Hz, as acceleration for tree initiation had been confirmed at 10 kVrms and 14 kVrms between the two frequencies. V-t characteristics for tree initiation rather than tree growth to bridge the electrodes were obtained for conventional type of treeing specimens with an embedded steel needle subjected to voltages from 2 kVrms to 14 kVrms. As a result, the n value in V-n t characteristics was confirmed to be 5.5 for neat epoxy and larger than 7 for nanocomposite. It was clarified that tree initiation V-t characteristics were improved by approximately one order of magnitude for the epoxy/nanoclay composite compared to the neat epoxy resin. To be precise, such an enhancement factor is one order at high field but even two orders at low field. Formed trees are field dependent. They are rather thick and short in shape at low field, but thin and long at high field. It is concluded from the analysis on the basis of interfacial models and other studies that initial trees are formed due to a PD erosion process at low field during a long time, but due to dielectric breakdown including charge trapping at high field for a short time.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"5 1","pages":"528-531"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88101513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical Analysis of Partial Discharges from Electrical Trees Grown in a Flexible Epoxy Resin","authors":"S. Dodd, N. Chalashkanov, J. Fothergill","doi":"10.1109/CEIDP.2008.4772838","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772838","url":null,"abstract":"Electrical treeing is a long-term degradation mechanism in polymeric insulation, which can lead to electrical failure of HV insulation systems. The rate at which trees grow across the insulation depends on the PD activity occurring within them and hence the detection of the onset of electrical treeing could be established by PD monitoring. In this paper, a statistical analysis of the partial discharges detected during the growth of trees in an epoxy resin will be reported. The aim of this work was to provide additional insight into the physical mechanisms that lead to the observed fluctuations in the partial discharge activity. The results demonstrate interesting correlations between a number of statistical parameters, such as average discharge magnitude and standard deviation in the partial discharge amplitudes. These correlations could also be related to physical parameters such as the applied voltage magnitude and the measured power dissipation due to the partial discharges occurring during tree growth. The implications of this work for deterministic methodologies for the simulation of tree growth as well as for condition monitoring using feature recognition strategies for the early detection of tree growth will be discussed.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"39 1","pages":"666-669"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74825283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of Partial Discharges from a Spherical Cavity within a Dielectric Material under Variable Frequency Electric Fields","authors":"H. Illias, G. Chen, P. Lewin","doi":"10.1109/CEIDP.2008.4772896","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772896","url":null,"abstract":"Partial discharge (PD) is a discharge event that does not bridge the electrodes within an electrical insulation system under high voltage stress. In high voltage components, the measurement of partial discharge is used in the performance assessment of an insulation system. Through modeling the discharge process a better understanding of the phenomena may be attained. Previous studies have considered the modeling of PD activity from a cylindrical cavity. However, this is a limited approach as the most common types of cavities found in the insulation materials are either spherical or ellipsoidal. This paper describes the development of a model for a spherical cavity within a homogeneous dielectric. The model developed has been used to study the influence of the applied frequency on partial discharge activity and obtained results are presented.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"37 1","pages":"447-450"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79387337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Partial Discharge Denoising using the Wavelet Packets Transform as a Preprocessing Step for Classification","authors":"D. Evagorou, A. Kyprianou, P. Lewin, A. Stavrou, V. Efthymiou, G. Georghiou","doi":"10.1109/CEIDP.2008.4772794","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772794","url":null,"abstract":"The identification of partial discharges in high voltage equipment has emerged as one of the most effective condition monitoring methods for assessing the integrity of the equipment under test. The fact that the application of PD monitoring methods is being applied online makes the measurements suffer from noise, inevitable at the measurement point, and reduces the sensitivity of the measurements. Signal processing methods to post process the measurements have been utilised, resulting not only in rejection of the noise and improvement of the sensitivity, but also in improved classification of the PD. A powerful noise rejection technique, the wavelet packets transform (WPT) has been extensively employed for the effective extraction of PD signals from noise. This technique is particularly useful in denoising signals which have transient characteristics. It expands the signal into different bases that are chosen adaptively according to a cost function, transforming the signal into a set of wavelet coefficients. The choice of a cost function has a significant effect on the compact representation of the signal. In this paper after the theory of wavelet packets is first briefly presented, and the denoising performance of the various wavelet packets parameters, such as the wavelet function, the thresholding type, and the cost function to be used is studied through the use of data acquired in a laboratory experimental environment for four types of discharges; namely the corona discharge in air, the internal discharge in oil, the floating discharge in oil and the surface discharge in air. The Symmlet wavelet has been compared with the Daubechies wavelet, both with 8 vanishing moments, the hard thresholding rule has been compared with the soft thresholding rule, and three cost functions have been compared as to their suitability for best basis expansion. Using some predefined criteria to assess their denoising performance the Symmlet 8 has been found to outperform the Daubechies 8 wavelet, the hard thresholding rule to yield better performance than the soft thresholding rule and the Shannon entropy cost function to perform better that the log energy and the norm energy cost functions.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"9 1","pages":"387-390"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83536950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Space Charge Formation in Epoxy Resin Including Various Nanofillers","authors":"A. Hajiyiannis, G. Chen, C. Zhang, G. Stevens","doi":"10.1109/CEIDP.2008.4772898","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772898","url":null,"abstract":"It has been widely anticipated that the combination of recent advances in nanocomposites technology with traditional and novel resin systems may create materials with enhanced electrical, thermal and mechanical properties. It has been recognised that charge dynamics under an electric field play an important role in determining the electrical performance of a material. In this research, the pulsed electroacoustic (PEA) technique has been used to measure space charge in epoxy anhydrite samples loaded with various nano-fillers. Space charge characteristics in both dried and wet samples have been measured at ~27 kV/mm. In addition to different charge dynamics, it has also been noticed that the electrical performance of nanocomposites has been affected in the presence of moisture. Further tests have been carried out at a lower field to reveal if different mechanisms take place.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"162 1","pages":"714-717"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76989322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Voltage Waveform on Phase-Resolved Electroluminescence Measurements","authors":"A. M. Ariffin, P. Lewin, D. Mills, S. Dodd","doi":"10.1109/CEIDP.2008.4772866","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772866","url":null,"abstract":"Space charge plays a significant role in long term electrical degradation of polymeric insulation in high voltage cables and consequently there is growing interest in the measurement of the energy dissipation of mobile and trapped charges in dielectric molecules. The dissipation process is associated with the emission of visible photons, a process known as electroluminescence (EL) and can be used, potentially, as an indicator for the initiation of electrical ageing of insulation. This paper presents the experimental work undertaken to examine EL from different ac applied voltages. Using a charge coupled device (CCD) detection system, the setup allows the determination of the light emission occurrence respect to the applied field. Phase-resolved EL measurements have been obtained using sinusoidal, triangular and square voltages.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"9 1","pages":"603-606"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91282268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time and spatial-resolved spectroscopic measurement system of PD light emission and its application to observation of PDs in SF6 gas","authors":"Y. Nakayama, M. Kamarol, T. Hara, M. Hikita, S. Ohtsuka","doi":"10.1109/CEIDP.2008.4772888","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772888","url":null,"abstract":"This study is aimed to sophisticate the simultaneous measurement system of electrical and optical information of PD phenomena, i.e. PD current and PD light emission phenomena. Using this sophisticated system, we can discuss and clarify the breakdown mechanism as well as the discharge condition such as streamer and leader discharge in SF6 gas or new SF6 substitute, based on observation results. In this paper, we described the structure and significance of the time and spatial-resolved spectroscopic measurement system. Then, we showed the measurement concept of PD phenomena and the main results obtained from this system with an electrode system forming non-uniform electric field in SF6 gas under ac high voltage application.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"20 1","pages":"439-442"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74575122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling and Parameter Estimation of High Voltage Transformer Using Rational Transfer Function State Space Approach","authors":"R. Mohamed, I. Markovsky, P. Lewin","doi":"10.1109/CEIDP.2008.4772922","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772922","url":null,"abstract":"Parameter estimation is an important technique for modeling of a high voltage transformer under wide frequency range. The complexity of the winding makes the system so complicated that a model of the real system over a wide range of frequency is difficult to achieve. This paper presents a technique in estimating the parameters of a high voltage transformer from the calculated impulse response. The approach is by modeling the rational transfer function using a state space approach that is called vector fitting. Then the inverse Laplace transform is used to estimate the response in the time domain which represents the approximate impulse response of the system. The estimation procedure of the signal parameters can be achieved using a simple calculation and parameter estimation technique.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"115 1","pages":"467-470"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85917327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of Discharges Propagating over Non-Uniformly Polluted Insulators under Impulse Voltages","authors":"A. Beroual, S. Diampeni","doi":"10.1109/CEIDP.2008.4772801","DOIUrl":"https://doi.org/10.1109/CEIDP.2008.4772801","url":null,"abstract":"This paper deals with the prediction of the characteristics of the whole discharge (length, current, arc resistance, instantaneous propagation velocity, charge injection, radius of the discharge and the voltage at the head of the discharge channel and the voltage drop within it) propagating over non-uniformly polluted insulators under impulse voltages using a dynamic model. This model uses an equivalent electrical network and an analytical impedance criterion. It takes into account the instantaneous changes of the discharge parameters. Simulation results for two bi-exponential waves are presented: 1.2/50 mus and 10/800 mus.","PeriodicalId":6381,"journal":{"name":"2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena","volume":"91 1","pages":"200-203"},"PeriodicalIF":0.0,"publicationDate":"2008-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85410896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}