Navegando por Assunto "Surge arresters"

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Acesso aberto (Open Access)
Análise de desempenho de pará-raios de ZnO sob diversos cenários de poluição utilizando método de elementos finitos
(Universidade Federal do Pará, 2022-08-16) LISBOA, Mellina Modesto; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
Metal-Oxide Surge Arrester is one of the protection devices of vital importance for Electric Power Systems and the equipment that composes them, since it ensures the reliability and continuity of operation of these systems based on their ability to attenuate transient overvoltage resulting from lightning strikes or switching surges. This equipment is formed by blocks of variable ZnO resistors, associated in series or in parallel, whose voltage-current curve presents high non-linearity. In view of the relevance of using the lightning rod, it is necessary to investigate its operating conditions. In the literature, several procedures and techniques are found for this purpose, among which monitoring through measurement and analysis of the leakage current stands out, since this represents one of the main factors that contribute to the degradation of this equipment. Given this context, the present master's dissertation implements a two-dimensional model of a 30 kV Zinc Oxide lightning arrester, using the Finite Element Method, to obtain the leakage current curves, electrical potential distributions, current density and that of electric field lines, when this device is subject to voltage variations and pollution conditions. The results show a significant increase in these measured quantities as the level of pollution intensifies, as well as with the increase in voltage levels.
Acesso aberto (Open Access)
Validação experimental de modelos elétricos de circuitos de ensaio de tensão residual em para-raios
(Universidade Federal do Pará, 2019-03-22) ASSIS, William Moreira de; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
This dissertation proposes the adoption of an electric model for residual voltage tests in zinc oxide (ZnO) arresters for standardized and non-standardized waveforms, using models of lightning already consolidated in the literature. The proposed model was validated from tests performed at the UFPA High and Extra High Voltage Laboratory (LEAT), obtaining results of residual voltage and discharge current measurements. In the tests, a 30kVrms nominal voltage arrester was used, subjected to a discharge current of 10kA with waveforms ranging from 8μs to 5μs of wavefront time. In order to vary the front and tail values of the impulsive waveforms, It was used the available inductors in the LEAT to change the values of the front and the tail of the impulsive waveforms. Additionally, simulations were performed in the ATP Draw software to evaluate the accuracy of the model for other waveform types, which initially could not be performed in the LEAT. The model result was compared to the measurement results. The model proved to be satisfactory for all impulsive waveforms. The parameters of the model are easy to determine, and all necessary information for the lightning arrester and pulse generator is contained in manufacturers' manuals and catalogs.