A corona is a type of plasma “atmosphere” of the sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. The Latin root of the word corona means crown. High electrical stresses applied to the surface of high voltage A.C transmission lines cause corona discharge near the surfaces. These partial discharges induce fast transient current pulses in the conductors. The induced pulses propagate in both directions along the multi–conductor transmission lines. The corona pulse sources are uncorrelated and uniformly distributed along the line. Transmission line conductor corona is responsible for many macroscopic phenomena on A. C transmission systems- foul weather (rain, fog, and snow and hoar- frost) can lead to discharge on high voltage transmission lines. These corona discharges result in a broadband crackling noise. In addition, in these situations with a low time at twice the mains frequency there often occurs a further noise component. Such audible noise from high voltage overhead transmission lines can reach locally undesirable levels. Both kinds of noise are associated with blemishes on conductors and other hardware surface and most importantly – water drops.
(1) Sarma Maruvada, P., “Coronaperformance of high voltage transmission lines”, Research studies press Ltd,England, 2002.
(2) Comber, M. G. and Nigbor, R.J, “Transmission line reference book – 345kV and above”, chapter 5, Radio Noise, EPRI, 2nd Edition, Revised 1989, pp. 205 –266.
(3) J.J. Clade, C.H. Gary, C.I.A. Lefevre, “Calculation of Corona losses beyond the critical gradient in alternative voltage”, IEEE Trans. PAS, Vol. 88, no5, pp. 695 – 703, 1969.
- Corona (egrejeen.wordpress.com)