Corona Effect

Introduction of Corona Effect

Brush discharge. As an example, high voltage on a sharp pointed wire can discharge through the surrounding atmosphere by ionization of the air molecules. This may be visible in the dark as a blush or reddish glow, called the corona effect.   Corona is undesirable, as it reduces the potential by brush discharge into the surrounding air.  In addition, the corona often indicates the beginning or a spark discharge.  A potential of the order of kilovolts is usually necessary for corona, as the breakdown voltage for air is approximately 20 kV/in. To reduce the corona effect, conductors that have high voltage should be smooth, rounded, and thick. This equalizes the potential difference from all points on the conductor to the surrounding air.  Any sharp point can have more intense fields, making it more susceptible to corona and eventual spark discharge