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Unformatted text preview: Corona Definition: The phenomenon of violet glow, hissing noise and production of ozone gas in an overhead transmission line is known as Corona. Corona formation: The value of the potential gradient at which the ionization takes place under normal temperature (25 C ) and pressure and without impurities is equal to 30KV(Peak)/cm and is denoted by g . Factors Affecting Corona: i) Atmosphere: As corona is formed due to ionization of air surrounding the conductors, therefore, it is affected by the physical state of atmosphere. In the stormy weather, the number of ions is more than normal and as such corona occurs at much less voltage as compared with fair weather. ii) Conductor size: The corona effect depends upon the shape and conditions of the conductors. The rough and irregular surface will give rise to more Corona because unevenness of the surface decreases the value of breakdown voltage. Thus a stranded conductor has irregular surface and hence gives rise to more corona than a solid conductor. conductor....
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This note was uploaded on 04/16/2011 for the course EEE 30 taught by Professor Dr.sohrabuddin during the Spring '11 term at American Intl. University.
- Spring '11