Corona

During cloudy, rainy weather the high voltage gradient at the surface of conductor may cause ionization of air surrounding the surface of conductor giving audible, violent visible, intermittent discharge corona. Corona losses are high on a new transmission line and n rainy season. Corona is accompanied by hissing sound, vibration, power loss and radio interference (R.I.). The phenomena of corona is accompanied by predominant third harmonic currents which cause radio interference in the adjacent communication circuits.