UV Corona
What is Corona and why is it a concern?
Corona is an electrical discharge (i.e. partial breakdown of air insulation) occurring in a high electric field, general in the vicinity of conducting surfaces, but also near insulating surfaces, due to the ionization of air.
Corona is a concern for utilities because it:
- Creates corrosive nitrogen oxides
- Creates nitric acid in the presence of water vapor
- Degrades polymer insulators
- Attacks galvanized steal and accelerates corrosion
- Causes pitting in cement and the metal caps of porcelain insulators
- Generates RFI and audio noise
- Indicates imminent flashover of insulators
How to identify corona
Corona generates very little heat and therefore difficult to detected with utility IR cameras. However, corona does emit radiation between 240nm and 405nm, mostly in the ultraviolet (UV) range and therefore is invisible to the human eye, all though relatively weak emissions at 400nm might be observed under conditions of absolute darkness. The corona emissions between 240nm and 405nm are not detectable during the day due to the high background of UV solar radiation.
How to see corona
Powerline Patrol Services uses the DayCor corona camera. It’s a bi-spectral Solar Blind UV-visible camera, designed to detect those very faint UV emissions in the solar blind UV band. This allows us to actually see the corona discharge as its taking place, pinpoint the source and measure the discharge intensity. With this information in hand maintenance crews can repair the exact cause of the corona and replace the affected components before electrical or mechanical failure.
3946 E. Andre Avenue
(480) 861-5804
(480) 361-9656
