Rethinking Conductor Selection for Structural and Economic Efficiency
As grid operators confront increasing demand, growing renewable integration, and heightened reliability expectations, efficient transmission design has become paramount. While many engineers rightly focus on voltage level, routing, and environmental constraints, conductor selection remains one of the most critical - and often under-leveraged - decisions influencing both upfront and lifecycle project costs.
The ACCC® Conductor, engineered with a high-strength, low-sag composite core and increased aluminum cross-section (without a weight or diameter penalty), enables substantial cost reductions in new line construction by decreasing structure counts, optimizing span lengths, and mitigating clearance challenges. This article quantifies those advantages using a representative 230 kV case study, comparing ACCC® Drake against legacy ACSR Drake designs.
Structural Cost Impacts: A 20-Mile, 230 kV Case Analysis
Based on the Midcontinent Independent System Operator (MISO) design guidelines, a typical 20-mile 230 kV single-circuit line constructed with ACSR Drake would require approximately:
- 240 tangent structures
- 40 running angle structures
- 20 dead-end structures (angled and non-angled)
Installed structure costs - factoring steel pole fabrication, foundations, labor, hardware, and equipment - range from $70,000 for tangent types to over $160,000 for dead-end assemblies. The cumulative structure-related expenditure for such an ACSR-based project is approximately $39.6 million.
When ACCC® Drake is used instead, its higher tensile strength and dramatically lower thermal expansion allow for longer average spans (~350 ft), reducing total structure count by roughly 15%. This translates to the elimination of ~50 structures, driving total structural costs down by over $5.9 million.
These savings are not limited to materials. They extend to:
- Foundation excavation and concrete
- Hardware kits and fasteners
- Crew labor and crane hours
- ROW access and staging requirements
Fewer structures also reduce permitting complexity and environmental disruption - particularly advantageous in rugged terrain, wetlands, or areas requiring lengthy agency coordination.
Total Installed Cost and Capacity Metrics
Beyond structural savings, a complete cost comparison highlights even greater capital efficiency:
Metric
ACSR Drake
ACCC® Drake
Total Installed Cost
$40.9 million
$35.8 million
Line Capacity (MVA)
359 MVA
717 MVA
Cost per MVA Installed
~$114,000/MVA
~$50,000/MVA
Despite slightly higher per-foot conductor costs, ACCC® delivers a net capital savings of over $5 million. More importantly, it doubles the current-carrying capacity without additional thermal clearance penalties.
Thermal Sag and Clearance Management
Unlike steel-core conductors (e.g., ACSR, ACSS), ACCC’s composite core exhibits a near-zero coefficient of thermal expansion. This trait is especially critical when operating at elevated temperatures:
- ACSS can operate at up to 250°C but experiences significant thermal sag, often requiring taller structures or shorter spans.
- ACCC®, operating at a conservative 180°C to 200°C, maintains clearance margins with less sag, enabling longer spans and fewer poles - without increasing tower height or compromising safety.
From a mechanical design standpoint, ACCC’s reduced sag behavior simplifies clearance modeling in PLS-CADD and allows engineers to take full advantage of higher thermal ratings without triggering NESC violations or structure redesigns.
Electrical Efficiency: Reducing Line Losses
In addition to structural and thermal benefits, ACCC® Conductor's greater aluminum content results in:
- Lower DC resistance
- Reduced I²R losses, especially at higher ampacity levels
- Improved system efficiency under peak load conditions
These characteristics reduce total energy losses over the asset’s life, providing both environmental and economic benefits. In large-scale systems, the compounded operational savings can exceed millions in deferred generation and lost revenue.
Engineering a Future-Ready Transmission Line
For transmission planners, the upfront capital cost savings associated with ACCC® deployment are measurable and immediate. But the longer-term advantages - greater current-carrying capability, reduced thermal sag, and lower line losses - further strengthen its value proposition.
In projects constrained by terrain, right-of-way, or environmental sensitivity, ACCC® allows for flexible routing, optimized span configurations, and fewer foundations. It effectively decouples thermal and mechanical limitations, allowing transmission engineers to unlock higher capacity without proportionally increasing structural demands.
Technical Support and Design Tools
CTC Global has supported over 1,350 ACCC® deployments worldwide. Our Application Engineers utilize PLS-CADD™, Finite Element Analysis, and our proprietary Conductor Comparison Program (CCP™) to help utilities design structurally efficient, high-capacity systems tailored to real-world conditions.
With a global manufacturing base of 35 certified conductor producers and nearly 100 trained Master Installers, CTC Global offers a fully supported engineering and implementation framework.
For detailed case assessments or design support, contact us at [email protected]