Question

Corona loss increases with:

• A. Decrease in conductor size and increase in supply frequency
• B. Increase in conductor size and decrease in supply frequency
• C. Increase in both conductor size and supply frequency
• D. Decrease in both conductor size and supply frequency

Hint:

To minimize corona loss, use larger conductors and operate at lower frequencies.

Answer 1

The Correct Option is A

Step 1: Corona loss occurs in high-voltage transmission lines where air ionization around the conductor causes power dissipation. 
Step 2: The corona power loss per unit length can be estimated using the formula: \[ P_c = f (V - V_c)^2 \frac{1}{\delta r} \] where \( f \) is the supply frequency, \( V \) is the operating voltage, \( V_c \) is the critical disruptive voltage, \( \delta \) is the air density factor, and \( r \) is the conductor radius. 
Step 3: From the formula, corona loss increases when: - Frequency (\( f \)) increases: The power loss is directly proportional to frequency. - Conductor radius (\( r \)) decreases: Smaller conductors increase the electric field intensity, resulting in higher ionization and corona effect. 
Step 4: Therefore, the correct answer is a decrease in conductor size and an increase in supply frequency.