scholarly journals A Novel Approach to Power Circuit Breaker Design for Replacement of SF6

10.14311/548 ◽  
2004 ◽  
Vol 44 (2) ◽  
Author(s):  
D. J. Telfer ◽  
J. W. Spencer ◽  
G. R. Jones ◽  
J. E. Humphries
Keyword(s):  
Circuit Breaker ◽  
Circuit Breakers ◽  
Power Circuit ◽  
Current Interruption ◽  
Novel Approach ◽  
Different Gases ◽  
Critical Contact ◽  
Made In ◽  
Gas Pressures

This contribution explores the role of PTFE ablation in enhancing current interruption for various background gases in high voltage circuit breakers. An assessment of the current interruption capability has been made in terms of the arcing duration and the contact gap length at which critical arc extinction is achieved. These observations are supported by measurements of the magnitude of extinction and re-ignition voltage peaks. Most previous and other current experimental work on gas filled circuit breaker design follows conventional wisdom in investigating arcing behaviours at elevated gas pressures (usually up to 6 bar). But in this work we concentrate on the effects of using low gas pressures (less than 1 bar) in the presence of a close-fitting shield of ablatant polymer material (PTFE) that surrounds the electrode assembly of an experimental high power circuit breaker. We demonstrate that for several different gases, arc extinction capability compares well under these conditions with SF6, suggesting that SF6 could be replaced entirely in this novel system by more environmentally friendly gases. Moreover, the critical contact gap lengths at extinction are only slightly greater than when using SF6 at 6 bar. Weight loss measurements from the ablatant shield suggest that a chemical puffer action is the most likely mechanism for achieving the observed arc extinctions in this system.

Electrical Stress Analysis of Switching Transients in 115 kV High Voltage Substation

2015 ◽  
Vol 781 ◽  
pp. 333-336
Author(s):  
Ratana Kem ◽  
Warunee Srisongkram ◽  
Phanupong Fuangpian ◽  
Thanapong Suwanasri
Keyword(s):  
Stress Analysis ◽  
Capacitor Bank ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Circuit Breakers ◽  
Power Circuit ◽  
Electrical Stress ◽  
Transient Recovery Voltage ◽  
Recovery Voltage

This paper presents electrical stress analysis from capacitor bank switching in a 115 kV substation. The actual data of all equipment in substation are used in the simulated circuit by using ATP/EMTP program. The cases study focused on the determination of proper value of series reactor, effect of circuit breaker pole discrepancy on inrush current, line model selection and load variation. Electrical stress from energizing inrush current as well as transient recovery voltage and rate of rise of recovery voltage imposed on power circuit breaker during capacitor bank has been analyzed. The obtained results are used as guidelines for analysis of the electric stresses on substation equipment while capacitor banks are energized. Moreover, those results can be used to select the proper rating of circuit breakers to withstand the electric stresses in the transmission network.

scholarly journals Technical Assessment of Hybrid HVDC Circuit Breaker Components under M-HVDC Faults

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8148
Author(s):  
Saqib Khalid ◽  
Ali Raza ◽  
Umar Alqasemi ◽  
Nebras Sobahi ◽  
Muhammad Zain Yousaf ◽  
...  
Keyword(s):  
Thermal Stresses ◽  
Circuit Breaker ◽  
Fault Isolation ◽  
Fault Current ◽  
Operational Parameters ◽  
Circuit Breakers ◽  
Current Interruption ◽  
Operational Conditions ◽  
Dc Fault ◽  
Protection Strategies

One of the technical challenges that needs to be addressed for the future of the multi-terminal high voltage direct current (M-HVDC) grid is DC fault isolation. In this regard, HVDC circuit breakers (DCCBs), particularly hybrid circuit breakers (H-DCCBs), are paramount. The H-DCCB, proposed by the ABB, has the potential to ensure a reliable and safer grid operation, mainly due to its millisecond-level current interruption capability and lower on-state losses as compared to electromechanical and solid-state based DCCBs. This paper aims to study and evaluate the operational parameters, e.g., electrical, and thermal stresses on the IGBT valves and energy absorbed by the surge arrestors within H-DCCB during different DC fault scenarios. A comprehensive set of modeling requirements matching with operational conditions are developed. A meshed four-terminal HVDC test bench consisting of twelve H-DCCBs is designed in PSCAD/EMTDC to study the impacts of the M-HVDC grid on the operational parameters of H-DCCB. Thus, the system under study is tested for different current interruption scenarios under a (i) low impedance fault current and (ii) high impedance fault current. Both grid-level and self-level protection strategies are implemented for each type of DC fault.

ASPECTS IN BUILDING A COMPANY WEB-SITE AND ITS ROLE FOR THE DEVELOPMENT OF BUSINESS

2018 ◽  
pp. 117-124
Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva
Keyword(s):  
Life Cycle ◽  
Web Site ◽  
The Internet ◽  
A Company ◽  
The Web ◽  
Design Construction ◽  
Made In ◽  
Site Types

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.

Aboutness

2014 ◽  
Author(s):  
Stephen Yablo
Keyword(s):  
Subject Matter ◽  
Philosophy Of Language ◽  
Mental States ◽  
Library Science ◽  
Philosophical Methodology ◽  
Major Advance ◽  
Truth Conditions ◽  
Ways Of Being ◽  
Made In

Aboutness has been studied from any number of angles. Brentano made it the defining feature of the mental. Phenomenologists try to pin down the aboutness features of particular mental states. Materialists sometimes claim to have grounded aboutness in natural regularities. Attempts have even been made, in library science and information theory, to operationalize the notion. However, it has played no real role in philosophical semantics, which is surprising. This is the first book to examine through a philosophical lens the role of subject matter in meaning. A long-standing tradition sees meaning as truth conditions, to be specified by listing the scenarios in which a sentence is true. Nothing is said about the principle of selection—about what in a scenario gets it onto the list. Subject matter is the missing link here. A sentence is true because of how matters stand where its subject matter is concerned. This book maintains that this is not just a feature of subject matter, but its essence. One indicates what a sentence is about by mapping out logical space according to its changing ways of being true or false. The notion of content that results—directed content—is brought to bear on a range of philosophical topics, including ontology, verisimilitude, knowledge, loose talk, assertive content, and philosophical methodology. The book represents a major advance in semantics and the philosophy of language.

The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms

2020 ◽  
Vol 27 (7) ◽  
pp. 1041-1051 ◽  
Author(s):  
Michael Spartalis ◽  
Eleftherios Spartalis ◽  
Antonios Athanasiou ◽  
Stavroula A. Paschou ◽  
Christos Kontogiannis ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Number Of Genes ◽  
Causes Of Mortality ◽  
Artery Disease ◽  
Genetic And Environmental Factors ◽  
Made In

Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.

Conclusions

2018 ◽  
Author(s):  
Amy Strecker
Keyword(s):  
International Law ◽  
Eu Law ◽  
World Heritage Convention ◽  
State Practice ◽  
The World ◽  
State Obligations ◽  
Made In ◽  
Landscape Protection

The final chapter of this book advances four main conclusions on the role of international law in landscape protection. These relate to state obligations regarding landscape protection, the influence of the World Heritage Convention and the European Landscape Convention, the substantive and procedural nature of landscape rights, and the role of EU law. It is argued that, although state practice is lagging behind the normative developments made in the field of international landscape protection, landscape has contributed positively to the corpus of international cultural heritage law and indeed has emerged as a nascent field of international law in its own right.

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