In low-temperature environments, the challenges facing conductors extend far beyond simply "becoming rigid." I understand your concerns regarding the operational stability of power infrastructure during severe cold-particularly during seasons of heavy wind and snow-when the failure of a single conductor can send shockwaves through the entire power supply network.
The common faults affecting conductors in low-temperature environments primarily include mechanical overload and conductor galloping caused by ice accretion; flashovers resulting from degraded insulation performance; brittle fracture of metal components; and loosened connections caused by thermal expansion and contraction. Among these, ice-related faults account for the largest proportion and constitute the primary focus of prevention and control efforts for power grid operation and maintenance during the winter season.
I. Conductor Icing: The Most Prevalent and Destructive Fault
1. Mechanical Damage
Line Breaks and Tower Collapses: Ice accretion increases the weight of the conductor; in severe cases, this weight exceeds the design load limit, leading to broken strands, severed conductors, or even the collapse of utility poles and towers.
Jumping Caused by Uneven De-icing: When ice accretion varies across different spans of a transmission line, or when ice sheds unevenly from specific sections, the resulting load imbalance can cause the conductor to "jump" or whip violently, leading to phase-to-phase short circuits.
Conductor Galloping: Ice accretion alters the aerodynamic profile of the conductor. Under wind loads, the conductor becomes susceptible to low-frequency, large-amplitude oscillations known as "galloping," which accelerates fatigue in hardware fittings and can result in severed conductors or damaged insulators.
2. Electrical Faults
Insulator Flashover (Ice Flashover): Ice accretion creates "ice bridges" between the skirts (sheds) of insulators, significantly reducing the effective creepage distance. During the thawing process, the high conductivity of the melting ice water makes the system highly susceptible to flashover-to-ground faults.
Phase-to-Phase Short Circuits: Conductor galloping or an excessive increase in sag (the downward curve of the line) can compromise the minimum safe clearance distances between conductors, leading to electrical discharge and short circuits.
II. Material and Connection Issues Caused by Low Temperatures
1. Embrittlement of Conductors and Hardware Fittings
Low temperatures reduce the toughness of metal materials. This is particularly pronounced at temperatures below -20℃, where components such as conductors, line clamps, and bolts become significantly more prone to brittle fracture.
2. Loose or Cracked Connections
Due to differences in the coefficients of thermal expansion among various materials, connection points are prone to loosening under repeated freeze-thaw cycles. This leads to increased contact resistance, triggering localized overheating and potentially resulting in burnout.
3. Aging or Damaged Insulation
Cable sheathing (typically PVC or rubber) becomes hard and brittle at low temperatures. It is susceptible to cracking-caused by bending, compression, or wind-induced swaying-which exposes the conductor and creates risks of short circuits or electric shock.
III. Compounded Risks from External Environmental Factors
Entanglement by Foreign Objects: Strong winds may blow lightweight debris-such as plastic sheeting or advertising banners-onto power lines. If subsequently coated by wet snow or ice, this debris significantly increases the structural load on the lines; alternatively, it may directly trigger a short circuit.
Ice Accumulation on Vegetation: When trees and bamboo within the power line corridor become encrusted with ice, their weight increases dramatically. This makes them prone to toppling over and falling onto the lines, resulting in circuit tripping or line breakage.
