2011 Electrical Insulation Conference (EIC).最新文献

{"title":"Evaluation of EL CID indications not associated with stator core interlaminar insulation faults","authors":"D. Bertenshaw, James F. Lau, D. Conley","doi":"10.1109/EIC.2011.5996157","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996157","url":null,"abstract":"The integrity of the interlamination insulation in large stator cores is commonly tested with EL CID. Some recent tests on large turbo-generators resulted in apparent faults indicated by axially aligned bands of negative and positive EL CID Quad signals nearly 180° around the machine. However no other sign of core fault could be determined. Investigation showed the core had been systematically stacked in 180° arcs using two different lamination materials. EL CID is normally insensitive to variation in core loss and permeability, however it will respond to steels of varying characteristics placed in the same circumferential plane. This paper shows observed data and a new technique to analyze the loss energy vector was developed to demonstrate how these Quad signal artifacts can develop. From this an analytical model based on data from the steel was able to numerically predict the observed signals. By elimination of all other possible sources of these signals, this was concluded to be the root cause. The material property variances were significant only at the low 4% flux levels used in the EL CID test. At full service flux the variances reduced to acceptable levels so do not impact on the high flux test or machine reliability.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"162 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115756890","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":"Analysis of influential factors on the underground cable ampacity","authors":"Youyuan Wang, Rengang Chen, Jian Li, S. Grzybowski, Taosha Jiang","doi":"10.1109/EIC.2011.5996192","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996192","url":null,"abstract":"The extensive usage of underground cables is a typical feature of modern power distribution networks. To analyze the influential factors on the underground cable ampacity, a new numerical method to calculate the ampacity of the underground cable is described in this paper. It is programmed by COMSOL software, which is based on the principle of heat transfer and the Finite Element Method. This model completely takes into account the local cable conditions and complicated variable external environments. Its parameters can be updated according to the change of these influencing factors. The developed model is applied to analyze the impact of the different influential factors on the underground cable ampacity. The results show that the underground cable ampacity depends on many of the installation properties and conditions, of which the soil thermal resistance, the environment temperature, the laying way (the cable spacing and the cable number in the trench) and the external heat source are the main factors. The underground cable ampacity increases with the increase of the soil thermal conductivity and the distance from the external heat source, while it decreases linearly with the increases of the environment temperature.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123730676","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":"Dielectric deamplification of multiphase cementitious composites in the frequency range of 0.5GHz to 4.5GHz","authors":"Tzuyang Yu","doi":"10.1109/EIC.2011.5996169","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996169","url":null,"abstract":"Dielectric properties (dielectric constant and loss factor) of hydrated cementitious composites (e.g., Portland cement paste and concrete) are the basis for the use of microwave and radar nondestructive testing/inspection techniques (such as GPR) in civil infrastructure systems (e.g., buildings and bridges). Among different types of cementitious composites, hydrated cement paste (hcp) is the major element providing the bonding strength in cementitious composites. Since hcp is porous and multiphase, its measured effective dielectric constant and loss factor are the function of not only frequency, temperature, and humidity but also its design parameters such as the water-to-cement (w/c) ratio. The removal of moisture content (liquid phase) in hcp materials is known as the dielectric deamplification in hcp and other cementitious composites. This phenomenon affects the performance of microwave/radar sensors when applied to concrete structures. It is also known that interactions among liquid phase (moisture), gaseous phase (voids), and solid phase (hcp) provide insightful information regarding material composition and structural integrity (e.g., cracking in hcp) of the composite. In this paper, the dependence of dielectric deamplification in hcp on the w/c ratio of hcp in the frequency range of 0.5∼4.5 GHz at room temperature (25 C) is investigated. Panel specimens made of hcp designed with different w/c ratios (0.35, 0.40, 0.42, 0.45, 0.50, 0.55) and cured for 7 days were prepared. Some hcp panels were oven-dried at 105 C in order to remove non-chemically bound moisture in hcp. Dielectric constant and loss factor of hcp panels were measured using an open-ended coaxial probe system and a network analyzer. From the measurements, it is found that the dielectric deamplification in the measured dielectric constant of hcp exhibits a pattern different from the one in the loss factor of hcp, while both patterns are related to the w/c ratio of hcp. This finding can be useful in predicting the material composition of hcp and other cementitious composites using microwave/radar sensors.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121813011","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":"Stator end winding vibration and temperature rise monitoring","authors":"P. Kung, Lutang Wang, M. Comanici","doi":"10.1109/EIC.2011.5996105","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996105","url":null,"abstract":"In most turbine generators, excessive vibration and thermal cycling weaken the insulation on the windings causing stator bar to fracture and leading to partial discharge (PD), which ultimately results in fire. Therefore, PD becomes extremely dangerous for large hydrogen cooled turbines because it might lead to explosion in the plant. These risks can be mitigated by using VibroFibre™ fiber optic vibration sensors and the Integrated Signal Conditioning (ISC) system as condition monitoring solution. This solution prevents unplanned down time by obtaining a warning against arcing and fire resulting from the measurement and trending of vibration amplitudes in the stator end windings. The presence of an alarm stops the machine for repair before a disaster occurs, resulting in a life extension of critical power plant assets by at least 200%. Inside power generators, there are high voltages and strong electromagnetic fields, and such hostile environment makes the use of ordinary piezoelectric vibration sensors impossible. In this case, fiber optic vibration sensors are the most effective solution. Yet, until now, only single channel fiber optic sensors have been available. They are hard to manage and require one full week of down time to install. Using a bundle of fiber optic vibration sensors and an ISC unit, the architecture can be simplified. Moreover, one-day installation can be achieved by gluing the sensors onto the end cap with high temperature epoxy. This results in instantaneous return on investment.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130211058","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":"Neural network based classification of partial discharge in HV motors","authors":"Yahya Asiri, A. Vouk, L. Renforth, D. Clark, Jack Copper NeuralWare","doi":"10.1109/EIC.2011.5996173","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996173","url":null,"abstract":"This paper discusses the general application of using Neural Networks (NN) to classify six different types of Partial Discharge (PD). Stator winding failures contribute about 30–40% of the total motor failures according to IEEE and EPRI. Ninety percent (90%) of electrical failures on High-Voltage (HV) equipment are related to insulation deterioration. Large datasets were collected for motors with PD defects as well as PD-free machines. The datasets of PD were pre-processed and prepared for use with a NN using statistical means. It was possible to utilise the advantages offered by multiple NN models to classify the PD defects with a maximum recognition rate of 94.5% achieved, whereas previous research work did not exceed a classification accuracy of 79%.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"321 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121839031","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":"Condition based maintenance for power transformers in service: Application of conventional and advanced diagnostic methods","authors":"J. Fuhr","doi":"10.1109/EIC.2011.5996160","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996160","url":null,"abstract":"The reliability of all HV-apparatus is strongly dependant on the ability of the insulating system to withstand the permanent electrical stress without any damage during the expected lifetime, typically more than 40 years in service. If Dissolved Gas in Oil Analysis (DGA) shows an increasing amount of fault gases the results are analyzed and the risk of the defect is judged by specialists. Due to the fact that DGA is a generic method, the location of the fault inside of the transformer is hopeless. Therefore additional diagnostic methods must be used (conventional and advanced) to identify and localize the source of the fault gases dissolved in the insulating oil. In this contribution it will be shown on practical examples, that it is possible to identify and localize the reason for the alarm or spontaneous outage of the transformer by consequent application of all existing methods (conventional and advanced) and by final \"in depth\" analysis of all available results.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122336367","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":"Insulation resistance measurements for machine insulation","authors":"A. Brown, É. David, M. Essalihi","doi":"10.1109/EIC.2011.5996158","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996158","url":null,"abstract":"In order to gain assurance that a machine winding insulation can safely withstand the service voltage and assess its reliability in operating conditions after a given number of years in service, dc tests have been used for decades. Some specific quantities, such as the 1-minute insulation resistance (IR) or the polarization index (PI), can be used to assess the condition of the insulation system. The minimum IR value recommended by the IEEE Std-43 for most ac windings built after about 1970 is 100 MΩ (corrected to 40°C). Whether this arbitrarily value is too high or too low is still under debate. This paper presents data from windings of various machines and shows how insulation resistance depends not only on the health of the insulation system but also on machine size and on insulation technology. A normalization technique using the winding capacity and considering the insulation technology is suggested in order to compare values between different machines or with individual bars or coils.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127902909","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":"Experimental investigation of dry band arcing on ADSS cables when spiral vibration dampers are installed","authors":"K. Prabakar, G. Karady","doi":"10.1109/EIC.2011.5996151","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996151","url":null,"abstract":"In order to damp wind induced Aeolian vibration and to avoid damage in all dielectric self-supporting (ADSS) fiber optic cables, spiral vibration dampers (SVD) are used. Dry band arcing is a phenomenon observed in ADSS cable, which damages the outer surface of the cable. Damages due to dry band arcing damper and cable are observed in the field. Effect of spiral vibration dampers on dry band arcing is investigated by performing experiments on cable samples. Leakage current measurements from the experiments are recorded. Simulation is performed to reproduce the experimental samples using commercially available software and the electric field distribution on the surface of the cable for two models is simulated. The simulation result is used to analyze the behavior of the arc. When the dampers are installed, an increase in the leakage current and electric field distribution is observed. A possible remedy could be to move the dampers near the middle of the span without reducing its effectiveness.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131261496","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":"Assessment of insulation condition of hydro generator stator bars after 40 years in service","authors":"T. Klamt, T. Hillmer, François Vannay","doi":"10.1109/EIC.2011.5996155","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996155","url":null,"abstract":"Long-term field experience and the knowledge of the condition of stator bar insulation after long periods of operation are key points for ensuring reliable operation of stator windings. The ALSTOM Micadur® insulation system, first introduced for generators in 1958, has such long-term field experience. This system is in service over the whole power range of hydro and turbo generators, represented by a fleet of more than 10,000 machines between 5 MVA and 1944 MVA. ALSTOM had the opportunity to investigate the condition of 8 operation-aged Micadur® bars of a hydro generator, since the owner was replacing the stator core and stator winding.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128169684","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":"MV cable termination failure assessment in the context of increased use of power electronics","authors":"U. Patel, S. Jayaram, A. El-Hag, Ravi Seetahpathy","doi":"10.1109/EIC.2011.5996190","DOIUrl":"https://doi.org/10.1109/EIC.2011.5996190","url":null,"abstract":"In this work, the performance of cable termination used in the context of increased use of power electronics is studied. The experimental work analyses the cable termination degradation process when exposed to steep front non-sinusoidal voltage waveforms. The Partial Discharge (PD) measurements are carried out before and after the accelerated aging experiment to study the insulation degradation under high frequency medium voltage stress. Results obtained from the surface temperature measurements using infra red camera are also used in the analyses.","PeriodicalId":129127,"journal":{"name":"2011 Electrical Insulation Conference (EIC).","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131888852","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}