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Corona discharge occurs more in
Humid Weather
Hot weather
Cold Weather
Any of the above
Humid Weather
Corona discharge occurs more frequently in humid weather because moisture in the air reduces the disruptive critical voltage of the surrounding dielectric (air). The presence of water droplets on the conductor surface creates irregularities that enhance the local electric field gradient, facilitating ionization.
Corona discharge occurs more frequently in humid weather because moisture in the air reduces the disruptive critical voltage of the surrounding dielectric (air). The presence of water droplets on the conductor surface creates irregularities that enhance the local electric field gradient, facilitating ionization.
VcтАЛ=moтАЛgoтАЛ╬┤rln(rdтАЛ) тАФ Critical disruptive voltage formula where ╬┤ is air density factor.
P=╬┤241тАЛ(f+25)drтАЛтАЛ(VтИТVcтАЛ)2├Ч10┬░тИТ5 тАФ Empirical formula for power loss per phase due to corona.
Corona is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is electrically charged. When the electric field strength exceeds the dielectric strength of air (approx. 30 kV/cm peak), air molecules break down into ions. Humidity increases air conductivity and provides nucleation sites, lowering the threshold for this breakdown.
Corona loss is directly proportional to the supply frequency (f).
Roughness factor (moтАЛ) is significantly affected by surface moisture and contamination.
Corona results in ozone formation, radio interference, and audible noise.
Higher humidity acts as a catalyst for ionization under high electric stress.
Acts as a surge discharge mechanism for transient overvoltages
Power loss
Radio and television interference
Corrosion of conductors due to ozone formation
Audible noise
Ozone production units
Pollution control (Electrostatic precipitators)
The disruptive critical voltage VcтАЛ is inversely proportional to the air density factor ╬┤.
Option B (Hot weather) generally results in lower air density, which might increase corona, but humidity (Option A) has a more direct and immediate impact on dielectric breakdown strength in practical power systems.
A is correct тАФ Humidity facilitates the ionization process by reducing the dielectric strength of the air surrounding the conductor.
Always remember that corona loss is directly proportional to (VтИТVcтАЛ)2; any factor that decreases VcтАЛ (like high humidity or surface dirt) will cause an exponential increase in power loss.