Electric Corona PD on high/medium voltage installations leads to loss of energy and to an accelerated aging of insulators.
- Ozone, acids
- Electromagnetic emissions
- Ultraviolet light
- High-frequency sound
- Audio noise
Thermodynamically, corona creates a non-thermal plasma where not enough energy is released to heat the gas in the corona region. Thermal cameras, therefore, miss to detect corona (not arcing nor sparks).
High-frequency sound, ranging 40-100kHz, is also created during the process due to collisions between space charges and air molecules. The human ear is sensitive to audible range of 20 to 20,000 hertz and therefore ultrasonic sensors are required to detect PD sound and transform them into audible noise.
Electric corona PD emits electromagnetic radiation in the UV region of the spectrum (240 – 400nm), and hence the term “corona”. Human eyes respond to wavelength from 380 to about 750nm and as a result need a DayCor® UV camera to see corona in daytime.
Sniffers that can detect chemical reactions outcome such as the formation of Ozone and nitrous oxide gases will indicate exiting ionization processes of partial discharge, but these are not feasible for monitoring powerlines.
As soon as the electric Corona PD is detected maintenance teams or manufacturers perform corrective actions in order to reduce the discharge and avoid further power loses.