Static Modelling of AC Flashover on Contaminated Insulators Covered with Ice Using Intelligent Identificat Ion Methods PDF Download
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Author: Yadollah Sabri
Publisher:
ISBN: 9781412316194
Category : Electric insulators and insulation
Languages : en
Pages : 364
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Book Description
Author: Yadollah Sabri
Publisher:
ISBN: 9781412316194
Category : Electric insulators and insulation
Languages : en
Pages : 364
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Book Description
Author: Shamsodin Taheri Ledari
Publisher:
ISBN: 9781412320306
Category :
Languages : en
Pages :
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Book Description
Author: Taheri Shamsodin
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659716140
Category :
Languages : en
Pages : 180
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Book Description
Ice and snow accretion on insulators has been recognized as a significant risk factor in the reliability of overhead transmission lines and substations. In the presence of a highly conductive water film on the surface of the ice, while applied voltage is sufficiently high, corona discharge activity may be initiated and developed into partial arcs. Under certain conditions, these partial arcs may result in complete flashover. This book aims to study the flashover phenomenon on ice-covered extra-high-voltage (EHV) post insulators. Hence, a two-arc dynamic model based on the existing mathematical models was proposed to predict the parameters of AC and DC flashovers. Moreover, the mechanisms of discharge initiation and arc development on the surface of the ice accumulated on the insulators were studied. The proposed models were successfully validated in laboratory using insulators, typically used in Hydro-Quebec 735 kV substations. This research may be regarded as an important basis for the development of multi-arc models and a powerful tool for the design and selection of EHV insulators subjected to ice accretion.
Author: Li He
Publisher:
ISBN:
Category : Electric insulators and insulation
Languages : en
Pages : 130
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Book Description
Transmission voltages worldwide are increasing to accommodate higher power transfer from power generators to load centers. Insulator dimensions cannot increase linearly with the voltage, as supporting structures become too tall and heavy. Therefore, it is necessary to optimize the insulator design considering all operating conditions including dry, wet and contaminated. In order to design insulators suitably, a better understanding of the insulator flashover is required, as it is a serious issue regarding the safe operation of power systems. However, it is not always feasible to conduct field and laboratory studies due to limited time and money. The desire to accurately predict the performance of insulator flashovers requires mathematical models. Dynamic models are more appropriate than static models in terms of the instantaneous variation of arc parameters. In this dissertation, a dynamic model including conditions for arc dynamics, arc re-ignition and arc motion with AC supply is first developed.For an AC power source, it is important to consider the equivalent shunt capacitance in addition to the short circuit current when evaluating pollution test results. By including the power source in dynamic models, the effects of source parameters on the leakage current waveform, the voltage drop and the flashover voltage were systematically investigated. It has been observed that for the same insulator under the same pollution level, there is a large difference among these flashover performances in high voltage laboratories and real power systems. Source strength is believed to be responsible for this discrepancy. Investigations of test source strength were conducted in this work in order to study its impact on different types of insulators with a variety of geometries.Traditional deterministic models which have been developed so far can only predict whether an insulator would flashover or withstand. In practice, insulator flashover is a statistical process, given that both pollution severity and flashover voltage are probabilistic variables. A probability approach to predict the insulator flashover likelihood is presented based on the newly developed dynamic model.
Author: Lin Bo
Publisher:
ISBN:
Category : Electric insulators and insulation
Languages : en
Pages : 53
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Book Description
This paper presents a theoretical model for evaluating flashover performance of insulators under contaminated conditions. The model introduces several new features when compared with existing models such as, the formation of dry bands, variations in insulator geometry and surface wettability. The electric field distribution obtained from software for 3-Dimensional models along with form factor are used to determine the dimensions of the dry bands and the onset of arcing. The model draws heavily from experimental measurements of flashover voltage and surface resistance under wet conditions of porcelain and composite insulators. The model illustrates the dominant role played by the insulator shape and housing material on the flashover performance.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Pollution of insulator surface could lead to a flashover of insulators. The flashover of insulators caused by pollution generally dominates at voltages above 500 KV. Mechanism of pollution flashover is very complex as it depends on numerous factors. Over the years researchers have presented various models for better understanding of flashover phenomenon and prediction of flashover voltages. Due to the complexity of the problem researchers made various assumptions to simplify the problem. The objective of this dissertation is to review and compare various models and to evaluate their capabilities in predicting the flashover voltages of insulators. Several models have been reviewed and out of these models, those which contain sufficient information for predicting the flashover voltages have been selected. The selected models have been applied to different types of insulators and the flashover voltages are calculated. In order to compare the models the conditions e.g. resistivity, under which the models are applied to insulators are kept the same. Five types of configurations of insulator models are considered, (i) 10 x 1 cm flat plate, (ii) 10 x 10 cm flat plate, (iii) cylinder, 100 cm long and 15 cm diameter, (iv) IEEE insulator and (v) Anti-Fog insulator. The calculated flashover voltages and other results are compared with each other and with experimental results.
Author: Prem K. Patni
Publisher:
ISBN:
Category :
Languages : en
Pages : 250
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Book Description
Author: Ravi S. Gorur
Publisher: Ravi s Gorur Incorporated
ISBN: 9780967761107
Category : Dielectrics
Languages : en
Pages : 268
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Book Description
Author:
Publisher:
ISBN:
Category : Electrostatic precipitation
Languages : en
Pages : 488
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Book Description
Author: R. Keith Mobley
Publisher: Elsevier
ISBN: 0080478697
Category : Technology & Engineering
Languages : en
Pages : 451
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Book Description
This second edition of An Introduction to Predictive Maintenance helps plant, process, maintenance and reliability managers and engineers to develop and implement a comprehensive maintenance management program, providing proven strategies for regularly monitoring critical process equipment and systems, predicting machine failures, and scheduling maintenance accordingly. Since the publication of the first edition in 1990, there have been many changes in both technology and methodology, including financial implications, the role of a maintenance organization, predictive maintenance techniques, various analyses, and maintenance of the program itself. This revision includes a complete update of the applicable chapters from the first edition as well as six additional chapters outlining the most recent information available. Having already been implemented and maintained successfully in hundreds of manufacturing and process plants worldwide, the practices detailed in this second edition of An Introduction to Predictive Maintenance will save plants and corporations, as well as U.S. industry as a whole, billions of dollars by minimizing unexpected equipment failures and its resultant high maintenance cost while increasing productivity. - A comprehensive introduction to a system of monitoring critical industrial equipment - Optimize the availability of process machinery and greatly reduce the cost of maintenance - Provides the means to improve product quality, productivity and profitability of manufacturing and production plants
