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Corona is likely to occur maximum in case of
Distribution lines
Transmission lines
Domestic wiring
Service mains
Transmission lines
Corona is an electrical discharge caused by the ionization of air surrounding a conductor, which occurs when the potential gradient at the conductor surface exceeds the dielectric strength of air ┬╖ It is most prevalent in high-voltage transmission lines because these lines operate at significantly higher voltages compared to distribution lines, domestic wiring, or service mains, thereby reaching the critical disruptive voltage more easily.
Corona is an electrical discharge caused by the ionization of air surrounding a conductor, which occurs when the potential gradient at the conductor surface exceeds the dielectric strength of air ┬╖ It is most prevalent in high-voltage transmission lines because these lines operate at significantly higher voltages compared to distribution lines, domestic wiring, or service mains, thereby reaching the critical disruptive voltage more easily.
VcтАЛ=g0тАЛтЛЕ╬┤тЛЕrтЛЕln(rDтАЛ) тАФ Critical disruptive voltage formula where g0тАЛ is the disruptive strength of air (approx 30 kV/cm peak).
When the voltage across a transmission line exceeds the critical disruptive voltage, the air surrounding the conductor becomes ionized ┬╖ This ionization leads to the formation of a luminous glow, production of ozone gas, and high-frequency noise ┬╖ The phenomenon depends heavily on the conductor radius, the spacing between conductors, and the atmospheric condition (air density, humidity, and surface roughness).
Corona loss is directly proportional to the square of the frequency and the square of the overvoltage (VтИТVcтАЛ)2.
It causes power loss, radio interference, and audible noise.
Higher line voltage significantly increases the probability and intensity of corona discharge.
Corona is reduced by using larger diameter conductors or bundled conductors.
Acts as a natural lightning arrester by dissipating high-voltage surges.
Provides a visual indicator of extreme electrical stress on lines.
Power loss in the transmission system.
Interference with nearby communication lines.
Production of ozone which can lead to the corrosion of conductors.
The critical disruptive voltage is the voltage at which the ionization starts.
Option A, C, and D are low-voltage systems where the operating voltage is typically far below the threshold required to ionize the air surrounding the conductors.
B is correct тАФ Transmission lines operate at high voltages that frequently exceed the critical disruptive voltage of air, leading to significant corona discharge.
Always remember that corona is primarily a voltage-dependent phenomenon; the higher the operating voltage level of the line, the greater the corona effect.