Coronagraphy

Coronagraphy

Corona :

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.
  • MicroPhone
  • 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