Published By: Orna Ghosh

Icing of Transmission lines.

Frozen snowy winter turns everything white, including the high voltage transmission lines.

Every winter several countries, face the problem of icing on transmission lines. It is the phenomenon in which ice or snow accretion on overhead transmission lines and other network equipment occur. Since time immemorial, combating this condition get challenging, especially in regions where the transmission system expanded over large areas.

The icing of transmission lines puts an adverse effect on the infrastructure, which eventually leads to the following :

Icing can cause a mechanical impact on the transmission lines. During this phenomenon, conductors and wires get overloaded with heavy icing. If it combines with wind forces, there are chances that wires might break or towers will collapse.

Galloping is instability caused due to wind power. It is a disturbing phenomenon that can lead to phase-to-phase flashover, short-circuits, power cut and other severe mechanical damage.

Sudden ice shedding from power transmission systems can induce high dynamic force that can lead to the clearance between the affected conductor and an adjacent phase, resulting in electrical flashovers. Ice shedding can lead to the failure of tower arms and cascade failure of adjacent ones too. Different forms of transportations and public safety falls at risk too.

Research is carried out on a large scale to solve the problem. As a result, experts came out with different ideas to combat the situation.

Anti-Icing Technique is where experts came out with ideas to prevent the accumulation of ice on transmission systems. There are mainly two types of anti-icing techniques- firstly, is passive coatings, and secondly is the use of active devices.

Passive coating techniques, such as solid coatings, adhesive coatings and freezing point depressants, are used as anti-icing techniques. It is due to their properties that decrease ice adhesion on the surface of the applicant.

The active devices such as the Ice Electrolysis system, active material, LC Spiral rods and Pulse Electro-Thermal De-Icer are anti-icing techniques.

De-Icing Technique uses the Joule effect to prevent the accretion of ice or snow on wires and conductors. For de-icing the ground wires, the current is passed through it, using an auxiliary transformer. They follow this procedure after the wire is electrically isolated from the towers. The Joule method is applicable for wires over several km.

Mechanical techniques are one of the techniques to use for the timely maintenance of overhead networks. These include scrapping methods and vibrating methods. The Mechanical techniques require less energy to prevent the overload of ice deposits on the transmission lines.