1,720,989 research outputs found
TN - Island Grounding System
No full textTN-island grounding system is an effective way to both protect persons from shock hazard in installations with contained demand load, and greatly limit electrical interferences among systems. This distribution system, which utilizes separation transformers, grounded on the secondary sides, allows one to supply loads broken into "islands" as independent electrical areas. TN-island fits best the supply of electrical installations in particular locations like moored pleasure crafts in marinas, fish farms, fish tanks, refrigerated containers in seaports, data centers, and construction sites. Additionally, by introducing the TN-island to provide power to dwelling units, regardless of their existing electrical distribution system, we can improve electrical safety and, at the same time, increase reliability since the "islands" are not electrically interfering with each other. Last but not least, the TN-island system, allows one to develop "hybrid" systems just for restricted electrical areas, for example, dwelling units, and can lead to a free choice of systems and standards (i.e. NEC-USA and IEC-UE). This would eliminate technical obstacles and discourage market barriers. Such a process is as crucial as it is inevitable, as a consequence of the current world globalization. This could promote electrical safety, better functionality, and lower cost
Evaluation of the prospective Joule integral to assess the limit short circuit capability of cables and busways
No full textTN - Island Grounding System and The House of The Future
No full textLow voltage, single-phase residential loads are usually supplied by the local utility, through a common distribution system (CDS) in a radial layout. In US and UE typical distribution systems, a faulted dwelling unit can affect a healthy one by transferring ground rise potentials, sometime dangerous. The authors propose a novel system defined as TN-island grounding system with the adoption for each customer of a local transformer (LT) with taps, grounded at the mid-point of the secondary winding, supplied by a common distribution system with the neutral grounded but not distributed. This solution allows to reach several goals: - to elevate the immunity of dwelling units, - to stop potential rises, due to ground faults, and of circulation of stray currents - to balance the distributed capacitance-to-ground - to limit the triplen current harmonics naturally caused by the LT - to supply more customers and locally high power common loads HPCL of buildings - to organize common emergency system (UPS and generator sets), common power system management, loads shedding, etc. Moreover, for special conditions (i.e. swimming pool, medical rooms, damp houses), the use of local transformers LTs allows to adopt proper reduced voltage system recommendable owing to the lower value of touch voltage and to adopt further local ungrounded system (IEC IT-system
The Electrical Systems of Roadway Tunnels: Safety Design and Ecomanagement
No full textThis paper discusses the design criteria for the electrical systems of roadway tunnels with particular regard to the safety in the daily operation and in the case of fire events. It proposes a fit distribution system and an adaptive criterion for the support lighting system in order to minimize costs and energy impact. Electric systems of roadway tunnels need sophisticated architecture to allow the presence of extensively distributed loads and more stringent installation requirements due to the presence of fire hazard. Mechanical and electrical design criteria must be based on equipment qualification categories (EQCs), which are characterized by thermal inherent resistance and environmental parameters. Design criteria must include variable configurations to simplify installation, allow flexible operation, and optimize the cost-benefit ratio. A special power distribution, herein defined as “brush distribution,” and a temperature zone classification are proposed for road tunnels with a higher risk in the case of a fire event. Therefore, this paper suggests as design parameters the temperature exposure levels characterizing the thermal demand in each zones and the EQCs in order to choose the equipment with adequate thermal resistance
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Of international terminology and wiring methods used in matter of bonding and earthing of low-voltage power systems
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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