University of Khartoum

Effect of Climatic Conditions in the Sudan on Corona Discharges

Effect of Climatic Conditions in the Sudan on Corona Discharges

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Title: Effect of Climatic Conditions in the Sudan on Corona Discharges
Author: Mohammed Ahmed, Yousif
Abstract: The present work investigates the effect of atmospheric humidity on corona inception voltage and the associated power losses. This study aims to give better insight into the design of transmission lines as Trans mission at extra high voltages, is largely governed by the line corona performance. Conclusions drawn are: 1) Increase in percentage relative humidity decrease with increasing relative humidity. 2) Positive corona inception voltage gradient is not consistent and so the effect of percentage relative humidity could not be evaluated. In any case, it appears to be negligibly small 3) Values obtained for negative corona inception gradients lie a little below the value of 40kv/cm due: to surface imperfections in the test rods 4) Two methods have been developed for corona and corona loss detection – a) ionization -detector: this only detects the incidence of positive coronal, and b) phase-shift detector: this shows incidence of lossy corona and how the losses developed with increasing voltage, 5) a) using method 4-b it has been shown that lossy corona occurs at a particular voltage corresponding with the negative corona inception voltage. The development of the loss with applied voltage was also indicated. b)corona power loss is affected by percentage relative humidity in the same way as the negative corona inception voltage gradient. Increase in percentage relative humidity lowers the negative corona inception voltage gradient and hence causes losses to occur earlier than if the humidity is lower. Thus the effects oral inception gradient and corona loss agree with one another. 6) a) flashover voltage (sinusoidal) is increased with increasing percentage relative humidity for all cage sizes used except the smallest one, whose variation is not definite. b) Flashover voltotage is about the same for the smooth rods and is a 1ittle lower for the stranded rod for all cage sizes the flashover voltage shows a linear increase with increasing cage diameter. 7) a) the positive impulse flashover voltage is again linear with cage size, and slightly larger than the sinusoidal flashover voltage. b) negative impulse flashover voltage varies or the different rod sizes, the stranded rod-shows the highest value of flashover voltage, Variation with different sizes of cage is linear. There is a large difference between the negative and positive impulse' flashover voltages for the same cage size.
URI: http://khartoumspace.uofk.edu/handle/123456789/13756
Date: 2015-06-22


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