31-08-2013, 04:28 PM
Corona Discharge
Corona Discharge.pptx (Size: 75 KB / Downloads: 42)
In a long transmission line some hissing noise and faint violet glow near the conductors is called corona effect…….
It mainly happens in overhead transmission and power transformer
CORONA
Thus the phenomenon of hissing noise , faint violet glow and production ozone gas surrounding the overhead lines due to ionization of air is called corona
The corona effect takes place when applied voltage exceeds the particular value ,which is called critical disruptive voltage..
Atmospheric conditions:
The most important atmospheric conditions are pressure and temperature .In dusty,rainy conditions the number of free electrons are more hence critical disruptive voltage is lower.
Size of the conductor:
The corona loss is directly proportional to the square root of radius of the conductor
Methods of reducing corona loss:
Increasing size of the conductor:
Provide spacing between the conductors:
Using hollow and hundled conductors: