Use of bundle conductors.....

Hello Mrudula,

I would like to share free RG's link regarding your question.

You can see very valuable papers in RG.

https://www.researchgate.net/search.Search.html?type=publication&query=measurement+of+corona+loss+in+HVDC+lines

increasing the conductor radius 

using bundled or hollow conductor 

use CC Rings, Corona Control Rings.

 Thank you very much!

Conceptual base for corona effect: local electric field exceeding the critical value, free charges and ionization process.

Possibilities to reduce corona effect: Lower applied voltage, larger diameter of the conductors, optimized arrangement and diameter of conductors when in bundle, suitable condition of the conductors surface (smooth, without nicks or burrs or scrapes), the condition of the hardware surface, its position and shape (rounded rather than sharp edges and no protruding bolts with sharp edges).

It has been seen that intense corona effects are observed at a working voltage of 33 kV or above. Therefore, careful design should be made to avoid corona on the sub-stations or bus-bars rated for 33kV and higher voltages otherwise highly ionised air may cause flash-over in the insulators or between the phases, causing considerable damage to the equipment.  The corona effects can be reduced by the following methods :

(i) By increasing conductor size.  By increasing conductor size, the voltage at which corona occurs is raised and hence corona effects are considerably reduced.  This is one of the reasons that ACSR conductors which have a larger cross-sectional area are used in transmission lines.

(ii) By increasing conductor spacing.  By increasing the spacing between conductors, the voltage at which corona occurs is raised and hence corona effects can be eliminated.  However, spacing cannot be increased too much otherwise the cost of supporting structure (e.g., bigger cross arms and supports) may increase to a considerable extent.

by use bundled conductors

by use ring

since the shape of conductors