Effect of Wind and Ice Coating on Overhead Transmission Lines

Explain the effect of wind and ice coating on overhead transmission lines.

When the transmission line is coated with ice and simultaneously subjected to wind pressure, the thickness and size of the conductor increases. This thickness depends upon weather conditions. This cause increase in weight of the conductor. Increase in weight increases the vertical sag.

The phase diagram of the weight and pressure applied to the conductor shown in below image

Normally the net wind pressure direction is taken into the horizontal direction to the line conductor. The direction of Ice coating and the original conductor weight pressure in the vertical direction.  So the total force on the high voltage line conductor is the vertical sum of the horizontal and vertical forces.

The sag equation for transmission line is as following,

S =Wtl²/8T

S represent the slant sag in a direction making an angle θ to the vertical.