Electron affinities of various impurities and their electron emission ionization energies are presented. When electrons and holes were injected into silicone oil with a thin-film tunnel emitter, the injecting voltage was influenced by the type of impurity and its amount. The electron affinity for an impurity was calculated from the difference between the injecting voltage in pure silicone oil and the voltage in silicone oil contaminated with the impurity. The energy which is required for electron emission from the impurity was calculated from the hole injection voltage for the contaminated silicone oil. According to the experimental results, the electron affinity and the energy for electron emission depended on the structure of the impurity. Impurities with high electron affinity or high electron emission capability had either large dipole moments or many pi electrons. Electron affinity of various impurities and the electron emission energy were mainly correlated to their acceptor number and their donor number, respectively. >
{"title":"The electron affinity and ionization energy of various impurities in silicone oil","authors":"N. Tsuchida","doi":"10.1109/14.212249","DOIUrl":"https://doi.org/10.1109/14.212249","url":null,"abstract":"Electron affinities of various impurities and their electron emission ionization energies are presented. When electrons and holes were injected into silicone oil with a thin-film tunnel emitter, the injecting voltage was influenced by the type of impurity and its amount. The electron affinity for an impurity was calculated from the difference between the injecting voltage in pure silicone oil and the voltage in silicone oil contaminated with the impurity. The energy which is required for electron emission from the impurity was calculated from the hole injection voltage for the contaminated silicone oil. According to the experimental results, the electron affinity and the energy for electron emission depended on the structure of the impurity. Impurities with high electron affinity or high electron emission capability had either large dipole moments or many pi electrons. Electron affinity of various impurities and the electron emission energy were mainly correlated to their acceptor number and their donor number, respectively. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90486587","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}
P. Levin, A. J. Hansen, D. Beatovic, H. Gan, J. H. Petrangelo
A set of computer programs designed for research and educational objectives in the analysis of low frequency electric and magnetic field phenomena is described. These programs are developed around a standard and easily extensible user interface, run on both PC-compatible and X window platforms, and offer the user a wide range of analysis tools. They are capable of solving Poisson's equation for arbitrarily shaped axisymmetric and two-dimensional geometries. >
{"title":"A unified boundary-element finite-element package","authors":"P. Levin, A. J. Hansen, D. Beatovic, H. Gan, J. H. Petrangelo","doi":"10.1109/14.212240","DOIUrl":"https://doi.org/10.1109/14.212240","url":null,"abstract":"A set of computer programs designed for research and educational objectives in the analysis of low frequency electric and magnetic field phenomena is described. These programs are developed around a standard and easily extensible user interface, run on both PC-compatible and X window platforms, and offer the user a wide range of analysis tools. They are capable of solving Poisson's equation for arbitrarily shaped axisymmetric and two-dimensional geometries. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75955605","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}
The luminous events associated with the breakdown along the surfaces of large band gap insulators such as polycrystalline alumina and monocrystalline quartz in vacuum were investigated using a phototube and a very sensitive photomultiplier tube (PMT). The spectral nature of the light emitted during breakdown was resolved (in terms of the wavelength) by interfacing a monochromator with the PMT. In the case of the monocrystalline quartz specimen, the breakdown luminosity was observed to be associated with defects located at 2.76 and 1.91 eV below the conduction band edge. The breakdown luminosity of polycrystalline alumina was found to be associated with the defects corresponding to energy levels at approximately 1.91, 2.25, 2.45 and 2.76 eV. The formation of these defects is discussed in terms of the nonstoichiometric nature of the lattice structure at the surface. The samples were found to emit light when no breakdown occurs. This emission is attributed to the deep level defects. The observed results suggest that the surface flashover process is primarily controlled by the defect or trapping centers located within the forbidden gap of the insulators. >
{"title":"Spectral nature of luminosity associated with the surface flashover process","authors":"T. Asokan, T. Sudarshan","doi":"10.1109/14.212244","DOIUrl":"https://doi.org/10.1109/14.212244","url":null,"abstract":"The luminous events associated with the breakdown along the surfaces of large band gap insulators such as polycrystalline alumina and monocrystalline quartz in vacuum were investigated using a phototube and a very sensitive photomultiplier tube (PMT). The spectral nature of the light emitted during breakdown was resolved (in terms of the wavelength) by interfacing a monochromator with the PMT. In the case of the monocrystalline quartz specimen, the breakdown luminosity was observed to be associated with defects located at 2.76 and 1.91 eV below the conduction band edge. The breakdown luminosity of polycrystalline alumina was found to be associated with the defects corresponding to energy levels at approximately 1.91, 2.25, 2.45 and 2.76 eV. The formation of these defects is discussed in terms of the nonstoichiometric nature of the lattice structure at the surface. The samples were found to emit light when no breakdown occurs. This emission is attributed to the deep level defects. The observed results suggest that the surface flashover process is primarily controlled by the defect or trapping centers located within the forbidden gap of the insulators. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74775224","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}
J. Belana, M. Mudarra, J. Calaf, J. C. Cañadas, E. Menéndez
Electrets of amorphous polyethylene-terephthalate were studied, using thermal windows to polarize and thermally stimulated depolarization current (TSDC) dielectric spectroscopy as an analysis technique. It was found that the polar peak ( alpha ) and the free charge peak ( rho ) show a maximal area at polarization temperatures, T/sub p/, called the temperature of optimal polarization, T/sub po/. The T/sub po/ of alpha is approximately=70 degrees C, and for T/sub p/, >T/sub po/ the temperature at which the maximum intensity appears remains constant with T/sub p/. For this range of temperature the intensity of the maximum decreases and the polarization is linear with 1/T/sub p/. The second peak, rho , which has a T/sub po/ approximately=87 degrees C, shows the maximum intensity at temperatures that are linear with T/sub p/, T/sub p/>T/sub po/. For this range of temperatures the intensity of the maximum decreases with T/sub p/ and the polarization is not linear with 1/T/sub p/. These results are compared with those obtained from polyvinylchloride and polymethylmethacrylate. >
{"title":"TSC study of the polar and free charge peaks of amorphous polymers","authors":"J. Belana, M. Mudarra, J. Calaf, J. C. Cañadas, E. Menéndez","doi":"10.1109/14.212253","DOIUrl":"https://doi.org/10.1109/14.212253","url":null,"abstract":"Electrets of amorphous polyethylene-terephthalate were studied, using thermal windows to polarize and thermally stimulated depolarization current (TSDC) dielectric spectroscopy as an analysis technique. It was found that the polar peak ( alpha ) and the free charge peak ( rho ) show a maximal area at polarization temperatures, T/sub p/, called the temperature of optimal polarization, T/sub po/. The T/sub po/ of alpha is approximately=70 degrees C, and for T/sub p/, >T/sub po/ the temperature at which the maximum intensity appears remains constant with T/sub p/. For this range of temperature the intensity of the maximum decreases and the polarization is linear with 1/T/sub p/. The second peak, rho , which has a T/sub po/ approximately=87 degrees C, shows the maximum intensity at temperatures that are linear with T/sub p/, T/sub p/>T/sub po/. For this range of temperatures the intensity of the maximum decreases with T/sub p/ and the polarization is not linear with 1/T/sub p/. These results are compared with those obtained from polyvinylchloride and polymethylmethacrylate. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73622196","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}
This short communication deals with the practical computation of the median rank function, F(i,n). F is the estimator of the cumulative probability of failure for the ith of n identically stressed samples. The exact values of the median rank function are easy to compute, using a reliable and easy-to-code algorithm presented in this paper. >
{"title":"A reliable algorithm for the exact median rank function","authors":"J. Jacquelin","doi":"10.1109/14.212241","DOIUrl":"https://doi.org/10.1109/14.212241","url":null,"abstract":"This short communication deals with the practical computation of the median rank function, F(i,n). F is the estimator of the cumulative probability of failure for the ith of n identically stressed samples. The exact values of the median rank function are easy to compute, using a reliable and easy-to-code algorithm presented in this paper. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77918037","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}
An attempt was made to use hidden Markov models (HMM) to classify partial discharge (PD) image patterns. After an introduction to HMM, the methodology and algorithms for evolving them are explained. The selection of the model and training parameters and the results obtained are discussed. The utility of the approach is evaluated by applying it to five types of actual PD image patterns. The performance of the HMM approach is shown to exceed that of neural networks. >
{"title":"Use of hidden Markov models for partial discharge pattern classification","authors":"L. Satish, B. Gururaj","doi":"10.1109/14.212242","DOIUrl":"https://doi.org/10.1109/14.212242","url":null,"abstract":"An attempt was made to use hidden Markov models (HMM) to classify partial discharge (PD) image patterns. After an introduction to HMM, the methodology and algorithms for evolving them are explained. The selection of the model and training parameters and the results obtained are discussed. The utility of the approach is evaluated by applying it to five types of actual PD image patterns. The performance of the HMM approach is shown to exceed that of neural networks. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82005980","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}
The thermally stimulated current (TSC) technique has been used to evaluate the degradation of polymeric insulation containing water trees. It is shown that, compared to the capacitance and tan- delta measurements, the TSC technique is more sensitive and can detect the degradation caused by water treeing. The TSC spectra change with the aging time of the polymeric insulation and the length of the water tree. >
{"title":"Thermally stimulated current technique to evaluate polymer degradation due to water treeing","authors":"S. Bamji, A. Bulinski, Y. Chen","doi":"10.1109/14.212255","DOIUrl":"https://doi.org/10.1109/14.212255","url":null,"abstract":"The thermally stimulated current (TSC) technique has been used to evaluate the degradation of polymeric insulation containing water trees. It is shown that, compared to the capacitance and tan- delta measurements, the TSC technique is more sensitive and can detect the degradation caused by water treeing. The TSC spectra change with the aging time of the polymeric insulation and the length of the water tree. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74134409","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}
D. B. Watson, S. K. Kho, K. Samuels, L. Ma, J. Chiu
A video camera has been used to categorize the flashover tracks between point-to-plane and wire-to-plane electrodes. Positive impulse flashover produces zigzag and forked tracks, while negative voltages produce smooth tracks. The location of the impact on the plane electrode was found to be a function of the applied voltage and the length of the gap. A space-charge model is put forward to explain these results. >
{"title":"Impulse flashover trajectory in air in nonuniform fields","authors":"D. B. Watson, S. K. Kho, K. Samuels, L. Ma, J. Chiu","doi":"10.1109/14.212245","DOIUrl":"https://doi.org/10.1109/14.212245","url":null,"abstract":"A video camera has been used to categorize the flashover tracks between point-to-plane and wire-to-plane electrodes. Positive impulse flashover produces zigzag and forked tracks, while negative voltages produce smooth tracks. The location of the impact on the plane electrode was found to be a function of the applied voltage and the length of the gap. A space-charge model is put forward to explain these results. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72818358","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}
A dynamic model that computes the flashover voltages of polluted insulators energized with DC voltage is presented. The salient feature of this model is that it takes into account the configuration of the insulator profile at every instant, which plays an important role in the flashover process of the DC polluted insulators. A number of practical insulator geometries have been studied, and the validity of the model is verified by comparing the computed results with the experimental results of previous researchers. >
{"title":"Dynamic arc modeling of pollution flashover of insulators under DC voltage","authors":"R. Sundararajan, R. Gorur","doi":"10.1109/14.212246","DOIUrl":"https://doi.org/10.1109/14.212246","url":null,"abstract":"A dynamic model that computes the flashover voltages of polluted insulators energized with DC voltage is presented. The salient feature of this model is that it takes into account the configuration of the insulator profile at every instant, which plays an important role in the flashover process of the DC polluted insulators. A number of practical insulator geometries have been studied, and the validity of the model is verified by comparing the computed results with the experimental results of previous researchers. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79088107","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}
A Monte Carlo simulation is carried out for SF/sub 6/ in uniform electric fields, with 7% and 14% overvoltages and at two gas densities at each overvoltage. The electron motion and avalanche growth are simulated by tracing individual paths, and the effect of space charge is included by solving the Poisson equation. The streamer propagation, the electron and positive and negative ion distributions and space charge fields are studied in detail as more time has lapsed after voltage application. The simulated streamer shape explains for the first time the dark space in SF/sub 6/ streamers observed experimentally. It is found that the mechanism of streamer propagation in an attaching gas is different from that in a nonattaching gas. The maximum field enhancement is just behind the streamer or between two successive streamers in SF/sub 6/. The anode-directed streamer propagates with a velocity of 10/sup 7/ to 10/sup 8/ cm/s, depending on the percentage of overvoltage and the gas number density. >
{"title":"Streamer formation and Monte Carlo space-charge field calculation in SF/sub 6/","authors":"J. Liu, G. Raju","doi":"10.1109/14.212251","DOIUrl":"https://doi.org/10.1109/14.212251","url":null,"abstract":"A Monte Carlo simulation is carried out for SF/sub 6/ in uniform electric fields, with 7% and 14% overvoltages and at two gas densities at each overvoltage. The electron motion and avalanche growth are simulated by tracing individual paths, and the effect of space charge is included by solving the Poisson equation. The streamer propagation, the electron and positive and negative ion distributions and space charge fields are studied in detail as more time has lapsed after voltage application. The simulated streamer shape explains for the first time the dark space in SF/sub 6/ streamers observed experimentally. It is found that the mechanism of streamer propagation in an attaching gas is different from that in a nonattaching gas. The maximum field enhancement is just behind the streamer or between two successive streamers in SF/sub 6/. The anode-directed streamer propagates with a velocity of 10/sup 7/ to 10/sup 8/ cm/s, depending on the percentage of overvoltage and the gas number density. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91308279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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