07-08-2012, 03:11 PM
Corona
Corona.ppt (Size: 454 KB / Downloads: 26)
What Is Corona?
Corona is a luminous discharge due to ionization of the air surrounding an electrode, caused by a voltage gradient exceeding a certain critical value.
Physical Parameters of Corona
Corona is caused by the ionization of the media (air) surrounding the electrode (conductor)
Corona onset is a function of voltage
Corona onset is a function of relative air density
Corona onset is a function of relative humidity
ADVANTAGES
It reduces the magnitude of high voltage steep fronted waves due to lighting or switching by partially dissipating as a corona loss.In this way it acts as a safety valve to some extent.
It prevents conductor from electrical surge.
It increases the virtual diameter hence conductor can carry more current.
It is used in photocopier andlaser printer.
DISADVANTAGES
Corona from conductors and hardware may cause audible noise and radio noise
Audible noise from conductors may violate noise standards
Radio noise from conductors may interfere with communications or navigation
Corona loss may be significant when compared with resistive loss of conductors
Corona can cause possible damage to polymeric insulators