Typically in early winter or late winter and early spring, cold snaps produce supercooled liquid precipitation in clouds that freezes directly into ice upon contact with ground objects, forming rime. In winter and spring, we often see a layer of crystalline snow and ice wrapped around or hanging from power lines and tree branches. This is rime. So, what are the hazards of icing on wires and cables? Are there any countermeasures?
What are the hazards of icing on wires and cables?
Because wires and cables are suspended outdoors, they are easily covered with snow and ice. When rime forms on wires or branches, the wires contract when they freeze. Combined with the vibrations caused by wind and the weight of the rime, these can cause power and telephone lines to collapse under the weight. This can lead to the collapse of several kilometers or even dozens of kilometers of power poles, disrupting power transmission and communications, and severely impacting local industrial and agricultural production.
What are some tips for frost-proofing wires and cables?
1. First, choose cables that can withstand the cold. As ice and snow settle on cables and into the gaps between them, the cables' center of gravity tends to shift toward the snowy area, generating a force that causes the cables to rotate, causing the snowball to grow larger and larger, ultimately breaking. Therefore, cable rotation is the primary cause of icing. If cables were rigid conductors, however, when sufficient snow accumulates, they are less likely to twist and will simply fall off the conductors. Furthermore, due to the varying hardness and density of cables, as snow gradually solidifies toward the ice, it will automatically break apart. Consequently, some manufacturers have taken advantage of this opportunity to develop new high-voltage overhead cables, the Aero-Z being the most renowned. Both Iceland and Czechoslovakia, the coldest countries in the world, use this AERO-Z conductor.
Second, apply antifreeze coating to wires and cables. Antifreeze coating is essentially a high-temperature thermal insulation coating or a reflective thermal insulation coating. It aims to prevent freezing by retaining heat. It generally also provides waterproofing, corrosion resistance, moisture resistance, crack resistance, fire resistance, and insulation.
Icing on transmission lines is a major natural disaster for power transmission. Icing can easily increase the weight of transmission lines, causing them to bend and sag. When icing is severe, exceeding the critical threshold for transmission line icing, it can cause towers to collapse, leading to power outages and even grid disconnection. Repairs are difficult and time-consuming. Antifreeze coatings on the market vary depending on the R&D capabilities of individual companies. Therefore, careful comparison and inspection are essential when purchasing.
