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Application of Park's power components to the differential protection of three-...

Oliveira, L. M. R.; Cardoso, A. J. Marques

This paper presents a new scheme for power transformers differential protection, in which the concept of the Park's instantaneous differential powers is introduced. The proposed method is able to detect winding insulation failures and to distinguish them from magnetizing inrush current transients. Experimental and simulation results are presented and discussed.


Power transformers winding fault diagnosis by the on-load exciting current exte...

Oliveira, L. M. R.; Cardoso, A. J. Marques; Cruz, S. M. A.

This paper presents the application of the on-load exciting current Extended Park's Vector Approach to diagnose incipient turn-to-turn winding faults in operating power transformers. Experimental and simulation test results demonstrate the effectiveness of the proposed technique, which is based on the spectral analysis of the AC component of the on-load exciting current Park's Vector modulus.




Power transformers behavior under the occurrence of inrush currents and turn-to...

Oliveira, L. M. R.; Cardoso, A. J. Marques

This paper intends to provide a detailed characterization of the transformer behavior under the influence of inrush currents and/or incipient winding faults. Experimental and simulation results are presented and discussed. Finally, a promising new method to identify inrush currents, and to distinguish them from internal faults, is suggested.


A permeance-based transformer model and its application to winding interturn ar...

Oliveira, L. M. R.; Cardoso, A. J. Marques

This paper investigates the behavior of power transformers under the occurrence of permanent or intermittent winding insulation faults.


Tracking the performance of world-ranked swimmers

Costa, Mário; Marinho, D.A.; Reis, V.; Silva, A.J.; Marques, M.C.; Bragada, José A.; Barbosa, Tiago M.

Tracking the swimming performance is important to analyze its progression and stability between competitions and help coaches to define realistic goals and to select appropriate training methods. The aim of this study was to track world-ranked male swimmer’s performance during five consecutive seasons (from 2003/2004 to 2007/2008) in Olympic freestyle events. An overall of 477 swimmers and 2385 season best perf...

Data: 2010   |   Origem: Biblioteca Digital do IPB

Can 8-weeks of training affect active drag in young swimmers?

Marinho, D.A.; Barbosa, Tiago M.; Costa, M.J.; Figueiredo, Catarina; Reis, V.M.; Silva, A.J.; Marques, M.C.

The aim of this study was to assess the effects of 8-weeks of training on active drag in young swimmers of both genders. Eight girls and twelve boys’ belonging to the same swimming team and with regular competitive participation in national and regional events for the previous two seasons participated in this study. Active drag measurements were conducted in two different evaluation moments: at the beginning of...

Data: 2010   |   Origem: Biblioteca Digital do IPB

Is front crawl swimming performance affected by hydrodynamic drag in young swim...

Silva, A.J.; Marques, M.C.; Garrido, N.; Barbosa, Tiago M.; Costa, M.J.; Louro, H.; Reis, V.M.; Marinho, D.A.

Swimming performance is affected by several factors including the hydrodynamic drag. Hydrodynamic drag is the force that a swimmer has to overcome in order to maintain his movement through water and is highly dependent on swimming technique. PURPOSE: To analyse in young swimmers the relationship between hydrodynamic drag and the front crawl performance. METHODS: 25 young swimmers (11 females and 14 males) parti...

Data: 2010   |   Origem: Biblioteca Digital do IPB


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    Financiadores do RCAAP

Fundação para a Ciência e a Tecnologia Universidade do Minho   Governo Português Ministério da Educação e Ciência Programa Operacional da Sociedade do Conhecimento União Europeia