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Technical Characteristics

Sag in Line Design

Conductor sag comes in three primary forms: thermal sag (from heat expansion), creep sag (from gradual material elongation over time), and load-induced sag (from external forces like ice and wind). TS Conductor's AECC technology effectively manages all three types: its carbon fiber core virtually eliminates thermal sag above the knee point temperature, prevents creep sag through its dimensionally stable composite core design, and handles load-induced sag with a respectable modulus of elasticity.

In transmission line design, conductor sag must be carefully evaluated to ensure adequate ground clearance under all conditions. There are three fundamental types of sag that must be considered: thermal sag, creep sag, and load-induced sag.

Thermal Sag

Thermal sag occurs as conductors heat up and expand during operation. The amount of thermal sag depends primarily on the core material’s coefficient of thermal expansion. Traditional steel-core conductors experience significant thermal sag due to steel’s relatively high thermal expansion coefficient. In contrast, composite core conductors use materials with much lower thermal expansion coefficients, resulting in significantly reduced thermal sag.

Creep Sag

Creep sag develops over time as conductor materials, particularly aluminum strands, gradually elongate under sustained mechanical loading. This is especially significant in conductors without dedicated strength members, such as AAC (All Aluminum Conductor) or AAAC (All Aluminum Alloy Conductor).

Traditional industry practice has been to project ten-year creep behavior based on relatively short-term laboratory tests (around 1,000 hours). However, this approach often underestimates long-term creep, as aluminum strands can continue to elongate well beyond the ten-year mark in conductors without dedicated strength members.

Load-Induced Sag

Load-induced sag occurs when external forces, primarily ice and snow accumulation, add weight to the conductor. The total load includes:

  • The conductor’s own weight
  • Accumulated ice and snow weight
  • Span length effects (longer spans mean more total weight)

A conductor’s response to these loads depends largely on its core’s elastic modulus. First-generation composite core conductors, which incorporated significant amounts of fiberglass, exhibited lower modulus values that could result in excessive load-induced sag. This contributed to a perception that all advanced conductors have sag problems under heavy loading.

Next generation advanced conductor AECC takes a different approach. By eliminating fiberglass, it achieves a respectable modulus that effectively manages load-induced sag. This enables the conductor to handle heavy ice loads and support longer spans, including major river crossings like those over the Mississippi River.

Comparing Sag Performance

TS Conductor’s AECC technology effectively addresses all three types of sag through its unique design:

Thermal sag is virtually eliminated above the knee point temperature. This is because once the fully annealed aluminum transfers its load to the carbon fiber core, any further temperature increase causes minimal thermal expansion due to the core’s extremely low coefficient of thermal expansion.

Creep sag is minimal because the carbon fiber composite core maintains its strength and dimensional stability over time. Unlike aluminum conductors that continue to elongate, or traditional designs where aluminum strands may creep, AECC’s core provides long-term mechanical stability.

Load-induced sag is effectively managed through the core’s respectable modulus. AECC’s carbon fiber core provides sufficient mechanical strength and modulus to handle ice and snow loading while maintaining appropriate sag levels for reliable operation. Aluminum alloy options are also available, should it be required for special project situations.

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Thermal Sag thumbnail
Technical Characteristics

Thermal Sag Behavior: Knee Points and Material Properties

Bi-component conductors, made with two different materials, exhibit a thermal "knee point" - a temperature at which the aluminum strands reach zero tension due to thermal expansion as the conductor heats up. Traditional ACSR exhibits a knee point around 125°C but can't operate there due to aluminum strand damage, while ACSS shows a lower knee point but experiences high sag above it due to steel's thermal expansion. TS AECC exhibits virtually no thermal sag above its knee point due to its carbon fiber core's extremely low thermal expansion coefficient.

Standard Installation thumbnail
Performance & Operation

Standard Installation and Maintenance

TS Conductor’s AECC is the only advanced conductor that is fully compatible with traditional ACSR/ACCC installation and maintenance practices, requiring no specialized training or equipment. The aluminum encapsulation layer acts as a protective cushion during compression fitting installation, achieving 100% compaction around the core and preventing moisture ingress. The pre-tensioned design allows for standard bending radius requirements (25 times the conductor's outer diameter), while the sealed nature eliminates special storage requirements, maintaining full mechanical and electrical properties even after extended storage.

Longevity by Design thumbnail
Performance & Operation

Longevity by Design

TS Conductor ensures long-term reliability through multiple design features addressing potential degradation mechanisms. The aluminum encapsulation prevents galvanic corrosion by eliminating moisture and oxygen contact with the core, while also protecting against matrix degradation from environmental factors. The design's system-level performance benefits from annealed aluminum strands that redistribute stress through controlled creep, and trapezoidal strand configuration enabling optimal energy dissipation without fatigue, while compression fittings create a solid metal surround achieving 100% compaction around the composite core.

Award-Winning Design thumbnail
Fundamental Technology

Award-Winning Design: Aluminum Encapsulated Carbon Core (AECC)

TS Conductor's award-winning AECC technology represents the next generation of advanced conductors. The design optimizes three critical components: a pre-tensioned carbon core (without glass fibers) that delivers maximum strength and stiffness with near zero thermal expansion, a seamless aluminum encapsulation layer that preserves core pre-tensioning and provides multiple protective functions, and trapezoidal strands made from annealed aluminum that maximize conductivity. This integration achieves superior performance across all key metrics while maintaining the built-in safety and reliability of traditional options, earning recognition from organizations like the U.S. Department of Energy, Public Utilities Fortnightly, S&P Global Platts, and Bloomberg NEF.