Metodo de calculo de isolamento de torres de transmissão de energis eletrica face ao risco desejado para surto de manobra

AUTOR(ES)

Manoel Eduardo Miranda Negrisoli

DATA DE PUBLICAÇÃO

1989

RESUMO

The cost of an electrical transmission line depends greatly on the cost of its towers, which in turn are priced according to their dimensions and weight. These factors are greatly influenced by the insulation and particulary by the dimensions of the air-gaps. Large air-gaps have lower risks-of-failure when submitted to a given electrical stress than srnaller ones. But there is a price to pay for the added safety in the form of higher prices.The purpose of this work is to present a method which permits an optimized design of the transmission towers insulating structures for a specified risk-of-failure, under different types of electrical stresses to which they might be submitted, considering statistica1 probabilities of unfavorable atmospheric conditions (pressure, temperature, humidity and wind speeds), amplitudes of voltage surges and its distribution along the line, as well as the number of parallel tower gaps and insulator swings. Conventional design methods are used for a preliminary design based on all .the types of overvoltage stresses and its risk of failure is calculated, considering the existing atmospheric conditions along the line route. If the calculated risk-of-failure does not comply to the.specified one, adjustments are made on the gap distances of the original design which presented highest risk and new values for the whole structure are calculated. New comparisons may indicate the netessity of new adjustments, which are made. This procedure is repeateduntil the design can be considered satisfactory andits risk-of-failure complies with the specified.one. To complete the tower insulation coordination project, a evaluation of lightining impulse performance, should be made.The tower dimensions might be changed, mainly with the aspects to insulators strings, if satisfactory performance is not achieved by the shielding cable position, with respect to the shielding angle and mutual coupling with phase cables

ASSUNTO(S)

isoladores e isolamentos eletricos energia eletrica - transmissão

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