Why corona loss is higher in AC compared to DC systems?

In the case of AC voltages, the dielectric losses are due to both resistive and capacitive components of the dielectric material (i.e. cage the air gap), whereas under DC voltages the losses are due to the resistance of the air gap only.

Does corona loss occur in DC?

Detailed Solution. The corona losses in transmission line Pc is proportional frequency, i.e. Hence, P c a c > P c d c or corona losses for standard AC transmission are greater than DC transmission. We can also say that corona losses in DC transmission are minimum.

How can corona loss in transmission line be reduced?

Corona discharge can be reduced by the following methods:

1. By increasing the conductor size: As explained above, larger the diameter of the conductor, lesser the corona discharge.
2. By increasing the distance between conductors: Larger the conductor spacing, lesser the corona.

How Corona affects the DC lines?

Corona discharge can cause an audible hissing or cracking noise as it ionizes the air around the conductors. This is common in high voltage electric power transmission lines. The corona effect can also produce a violet glow, production of ozone gas around the conductor, radio interference, and electrical power loss.

Is corona more in DC lines or AC lines?

Both AC and DC transmission lines have positive and negative corona. This build-up of space charge surrounding a DC transmission line has the further effect of reducing the electric field very near each conductor.

How corona is formed in transmission line?

Definition: The phenomenon of ionisation of surrounding air around the conductor due to which luminous glow with hissing noise is rise is known as the corona effect. Air acts as a dielectric medium between the transmission lines. And this charging conductor increases the voltage of the transmission line.

In what shape of the conductor corona loss is less?

Under certain conditions, the localized electric field near energized components and conductors can produce a tiny electric discharge or corona that causes the surrounding air molecules to ionize, or undergo a slight localized change of electric charge. For circular conductors the corona loss is less.

What are the advantages of corona loss?

The main advantages of corona effects are:

• Due to corona across the conductor, the sheath of air surrounding the conductor becomes conductive which rises the conductor diameter virtually.
• Effects of transients produced by lightning or electrical surges are also reduced due to the corona effect.