A. Size of the conductor
B. Shape of the conductor
C. Surface condition of the conductor
D. All of the above
Answer: D. All of the above
B. Shape of the conductor
C. Surface condition of the conductor
D. All of the above
Answer: D. All of the above
Explanation:
The phenomenon of ionization of surrounding air around the conductor due to which luminous glow with hissing noise is rise is known as the corona effect.
Factor affecting Corona
Effect of supply voltage :
- If the supply voltage is high corona loss is higher in the lines.
- In low-voltage transmission lines, the corona is negligible, due to the insufficient electric field to maintain ionization.
The condition of conductor surface :
- If the conductor is smooth, the electric field will be more uniform as compared to the rough surface.
- The roughness of the conductor is caused by the deposition of dirt, dust and by scratching, etc.
- Thus, rough line decreases the corona loss in the transmission lines.
Air Density Factor :
- The corona loss in inversely proportional to air density factor, i.e., corona loss, increase with the decrease in density of air.
- Transmission lines passing through a hilly area may have higher corona loss than that of similar transmission lines in the plains because in a hilly area the density of air is low.
Effect of system voltage :
- Electric field intensity in the space around the conductors depends on the potential difference between the conductors.
- If the potential difference is high, the electric field intensity is also very high, and hence corona is also high.
- Corona loss, increase with the increase in the voltage.
The spacing between conductors :
- If the distance between two conductors is much more as compared to the diameter of the conductor than the corona loss occurs in the conductor.
- If the distance between them is extended beyond certain limits, the dielectric medium between them get decreases and hence the corona loss also reduces.