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Santos J.C.,University of Sao Paulo | De Sillos A.C.,University of Sao Paulo | Nascimento C.G.S.,Companhia de Eletricidade Do Estado da Bahia COELBA
2014 IEEE International Workshop on Applied Measurements for Power Systems, AMPS 2014 - Proceedings | Year: 2014

This paper presents the development of a system based on optical current transformers (OCTs) and optical voltage transformers (OVTs) for on-field calibration of conventional instrument transformers (ITs), avoiding necessities of removing the equipment for laboratory environment and interruption of supply for on-field calibration procedures. To accomplish these aims it was required the development of suitable OVTs and OCTs with accuracy classes equal to or better than 0.03%, suitable for calibration of conventional ITs intended to supply measuring instruments (accuracy classes equal to 0.3%). It was also necessary to develop the appropriate methodology to perform expedite on-field calibration of conventional ITs without interruption of service. As a further result of project, the on-field calibrations results may provide to sponsor utility recommendations for its maintenance procedures, aimed at replacing the identified off-class ITs or allow the use of algorithms for errors/losses compensation to be implemented on measuring instruments, in case of such resource be available. © 2014 IEEE. Source


Akishino J.K.,Federal University of Parana | Akishino J.K.,LACTEC Institute of Technology for Development | Cerqueira D.P.,Companhia de Eletricidade Do Estado da Bahia COELBA | Silva G.C.,LACTEC Institute of Technology for Development | And 4 more authors.
Thermochimica Acta | Year: 2016

The thermal behavior and the morphology of blends of polyethylene wax and paraffin were investigated to evaluate the feasibility of using these materials to obtain a new temperature-indicating device to use in order to indicate failures in electrical connections due to overheating. The samples were evaluated with differential scanning calorimetry (DSC), X-ray diffraction (XRD) and dynamic mechanical thermal analysis (DMTA). The results showed that the crystallinity decreases as the concentration of polyethylene wax increases. In the compositions tested, the components were not miscible in the crystalline phase, and these compositions exhibited solid/liquid transitions at temperatures between those of the individual components. © 2016 Elsevier B.V. All rights reserved. Source


Portellaa K.F.,Federal University of Parana | Mengarda P.,Federal University of Parana | Braganca M.G.P.,Federal University of Parana | Ribeiro S.,Federal University of Parana | And 4 more authors.
Materials Research | Year: 2015

In this study, the cold plasma technique was used to produce nanometric titanium films with hydrophobic and anti-fouling properties. The films where deposited on porcelain electrical insulators surfaces to minimize the effects of leakage current. The magnetron sputtering technique was used with a target of pure titanium sheet, and argon as the ionization gas. The deposited films present an average thickness of 58 to 350 nm. After coating the insulators, the assays performed indicated a greater degree of hydrophobicity and maintenance of leakage current after exposure to salt spray. Lower leakage current values were observed in both natural and saline environments compared with the uncoated device. Source


Cesar S.F.,Federal University of Bahia | Cunha R.D.A.,Federal University of Bahia | Ferreira S.N.M.,Companhia de Eletricidade Do Estado da Bahia COELBA | Revilta M.M.,Companhia de Eletricidade Do Estado da Bahia COELBA
11th World Conference on Timber Engineering 2010, WCTE 2010 | Year: 2010

Many electric companies in Brazil use native wood crossheads or concrete crossheads. In Bahia, its Electric Company - COELBA has reduced the use of crossheads made of native wood, for environmental reasons, but the use of wooden crossheads cannot be eliminated at all, due to technical reasons. In order to minimize the problem of the use of wood, this study was developed, in a partnership with COELBA, Federal University of Bahia and CM Venturoli (a wood company) and it resulted in a model of a wooden crosshead (made of eucalyptus), in order to in a near future substitute concrete crossheads made of native wood. This study aims to present a new product which has the technical qualities for the crossheads that are used in electric distribution systems, and which reduce environmental costs, using more sustainable raw material, like eucalyptus. In this context some eucalyptus crossheads had been tested in their product design study, analysis of the production process - to define specifications - and also through resistance tests to measure mechanical performance. Source

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