Advantage and Disadvantage of Corona

Corona has many advantages and disadvantages. Therefore for designing a transmission line, care must be taken to have a balance between the advantage and disadvantage of Corona.

Advantage of Corona

Following are some of the advantage of corona:

• The effective diameter of power conductor increases due to Corona. How? Actually, due to corona, the air surrounding the conductor becomes conductive and hence effective diameter increases. Due to this increase in effective diameter, the shunt capacitance of line increases. Due to increased effective diameter, electrostatic stress between the power conductors reduces.

• Corona helps to reduce the effect of transient produced by surge by dissipating the surge energy partially. Due to corona, the steepness of surge is reduced.

Disadvantage of Corona

• We know that, corona causes power loss. Due to this power loss, the transmission efficiency reduces.

• Ozone is produced due to Corona. This Ozone may cause degradation of conductor due to chemical action.

• Corona is basically discharge of current in air. This current is not sinusoidal rather it is non-sinusoidal. Because of this no-sinusoidal current drawn due to Corona, non-sinusoidal voltage drop occurs in the transmission line. This non-sinusoidal voltage drop may cause inductive interference with the neighboring communication line.

• Overhead transmission line do not interfere with TV or Radio Signals. But the two major source for causing interference are Corona and Gap Discharge. Due to corona, unwanted signals are generated. The strength of such noise decrease with increase in distance from the line and frequency. These noise may interfere with the TV or Radio Signal if their quality is poor. Gap discharge is entirely different from the Corona. Gap Discharge can take place at any voltage. Basically it is current discharge in a gap in between the two mechanical connected metallic parts. Such a discharge again results in generation of unwanted signal or noise. These noise may interfere with the Radio or TV signals.