- Corona is in UV region ( 240nm to 280 nm)
- When voltage on an electrical conductor exceeds threshold value, the air around it begins to ionize to form a blue or purple glow. Corona is the polarization of air molecules due to energy on high voltage.
- When voltage on an electrical conductor exceeds threshold value, the air around it begins to ionize to form a blue or purple glow.
- Corona is the polarization of air molecules due to energy on high voltage.
- When Ac potential difference is applied across two conductors whose spacing is large as compared to their diameters and the Pd. is increased then a point is reached when a faint luminous glow of bluish color appears along the length of the conductors and at the same time a hissing noise is heard. This bluish discharge is known as corona.
This process is accompanied by excitation of Nitrogen molecules and by chemical reactions, leading to:
- Production of corrosive chemicals like: Ozone and Nitrogen Oxides. At high humidity the oxides will create Nitric acid – a very corrosive material which removes the plating & causes corrosion of steel parts, conductors and insulators.
- Corona on insulators is an indication of ionization voltage at that point due to contamination or damage, either of which can lead to flashover. Ozone is harmful to human lungs & eyes.
- Radio interference.
- Audio noise.
- Emission of UV radiation.
Defects due to High Corona :
We are having most advanced daytime corona imaging equipment for predictive and preventive maintenance. The technical features DayCor® camera superb include:
- Built in Video recording and image captive system.
- 512 MB Flash card.
- USB Card Recorder.
- 2 Rechargeable 13 V Nimh batteries.
- Battery house.
- 1 Smart battery charger.
- AC, 12 V adapter.
- Ruggedized transport case.
- Ofil data base & reporting s/w etc.
- We have facility of detection of corona in the daytime since this camera can work in solar blind UV band.
Corona observed at 400 kV S/s