FAQs
3M™ Aluminum Conductor Composite Reinforced (ACCR) delivers two to three times the power
What is 3M™ ACCR?
How can 3M ACCR save me money if it is priced higher than other conductors?
What does 3M ACCR do?
How is it different from other new technologies claiming high performance?
What does it cost?
How do you install 3M ACCR?
Are accessories, such as connectors, splices, etc., available?
What kind of testing has been done on the equipment, and can I see the test results?
What are the typical uses for the new conductor?
From a planning perspective, what does the conductor do for me?
What does the conductor look like?
Do you have any current installations of 3M ACCR?
What types of conductors are available, and what are their electrical properties?
Q: What is 3M™ ACCR?
A: 3M™ Aluminum Conductor Composite Reinforced (ACCR) is a proven, high voltage overhead conductor. Designed as a drop-in replacement for ACSR and ACSS on thermally-limited lines, it provides higher ampacity with less thermal expansion (sag) than conventional conductors of similar size while maintaining or improving mechanical loads, tensions and clearances.
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Q: How can 3M ACCR save me money if it is priced higher than other conductors?
A: By eliminating the need for expensive new towers and tower construction, land acquisition, lengthy and controversial permitting processes, and long construction outages, upgrading with 3M ACCR can offer substantial savings even at a higher conductor cost-per-mile, especially for your toughest upgrade challenges. 3M ACCR can also provide more capacity for the same size conductor as even other high temperature low sag conductors.
See Less Time, Less Money for an actual customer example.
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Q: What does 3M ACCR do?
A: Depending on the application, 3M ACCR can carry two to three times the current of a standard cable of comparable size, with less sag, requiring few, if any, structure modifications. In addition, 3M ACCR can be installed to meet your tension and clearance requirements.
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Q: How is it different from other new technologies claiming high performance?
A: In general, the differences between 3M ACCR and other "high performance" conductors are due to the differences in the materials used. Compared to steel core conductors, for instance, the same size 3M ACCR can carry more current load with less sag. It is also lighter. The installation procedures are similar to ACSR, meaning most installers can quickly learn them. But, whatever your application, 3M offers a total solution, from design through installation support, backed by our long history of innovation in the electric utility industry.
3M ACCR's core relies only on aluminum-based materials. The core is a revolutionary aluminum alloy that has the strength and stiffness of steel with a lower coefficient of thermal expansion (less sag) and less weight. ACSR and ACSS use steel, and ACCC has a core composed of carbon fiber in a polymer matrix.
3M ACCR's core is surrounded by hardened, temperature-resistant aluminum-zirconium. 3M ACCR has an operating temperature of 210°C and an emergency temperature of 240°C. Although ACSS is designed to run at similar temperatures, it does not have the comparable low sag properties. In contrast, Aluminum Conductor Steel Reinforced, or ACSR, is rated to 100°C continuous, 150°C emergency.1
1Systems Analysis, Inc., Application Guides - Equipment Damage Curves Conductors, 2006, www.skm.com.
ACCC has a core made of a carbon fiber composite. The outer layer is softer aluminum. Based on information obtained from CTC's website, its conductor is rated at an operating temperature of 180 °C, with a recommended short term maximum operating temperature of 200°C. The glass transition temperature (Tg) of the core is 215°C. At temperatures over the Tg, the properties of the core change and strength may be affected.
3M ACCR is highly resistant to galvanic corrosion. The aluminum outer wires in 3M ACCR are chemically compatible with the aluminumoxide core. ACSR and ACSS use steel, which requires a zinc-based coating to prevent corrosion, and ACCC's carbon-based core relies on a glass barrier to prevent galvanic reaction between the core and the outer wires. If damage occurs to these barriers or coatings, the corrosion resistance of the product could be compromised.
3M ACCR has been successfully installed and operated as expected in all of its installations, with no field failures.
3M holds at least eighteen patents on the technology related to ACCR technology. The product has been recognized by R&D Magazine with an R&D 100 Award as one of the most technologically significant products introduced into the marketplace and by the Minnesota High Tech Association with a Tekne Award for innovative development. In addition, ACCR was one of the technologies that President George W. Bush viewed during a recent visit to 3M.
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Q: What does it cost?
A: The cost of the conductor varies depending on size and specifications, which are based on the specific application. Although 3M ACCR may generally cost between 3 to 6 times more than other conductors, it can save you money by eliminating the need to engage in long and risky construction projects, build towers, expand rights of way and participate in extended permitting and land acquisition processes. As a guideline, 3M ACCR is generally cost competitive when 30 to 40% of the structures need to be replaced. Every application is unique, however, so please contact us by clicking on Get Started to discuss your specific needs.
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Q: How do you install 3M ACCR?
A: 3M ACCR is specifically designed to be installed in a way that is similar to how ACSR is installed. Because the outer wires are hardened aluminum, they are more resistant to damage and bird caging during installation than ACSS and ACCC, which use annealed aluminum. In addition, we offer installation training and support through the duration of your project by a knowledgeable and dedicated team that understands overhead transmission and has broad experience in materials science, conductor mechanics and behavior, accessories, transmission line design and installation. See Installation Guides
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Q: Are accessories, such as connectors, splices, etc., available?
A: Yes. 3M, in cooperation with industry-recognized accessory suppliers, developed a complete set of accessories. Although these accessories are designed especially for use with the 3M core material and higher operating temperatures, they are similar to conventional accessories, as is the installation process. ACA Conductor Accessories (ACA) provides compression-type hardware, and Preformed Line Products (PLP) provides helical-rod type. All hardware is rated for high temperature operation. See Accessories
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Q: What kind of testing has been done on the equipment, and can I see the test results?
A: 3M ACCR has undergone thorough and rigorous laboratory and field testing. Multiple conductor constructions were tested to yield basic design parameters such as tensile strength, stress-strain curves, creep exponents, thermal expansion coefficients, sag-temperature-tension response, weight, diameter, and electrical resistance. All tests showed that the materials behaved as expected and that the behavior on a transmission line can be predicted using standard transmission design software and design approaches. Data is provided in laboratory & field tests and is embedded in the conductor design offerings.
Once basic design data were obtained, the constituents, conductor, and accessories were subjected to a wide range of standard and accelerated tests designed to provide life-aging data and secure increased confidence in the longevity of the system. Where possible, existing test standard protocols were used or, if necessary, were adapted to reflect the greater performance range of the system (e.g., higher temperatures). Life-aging data was collected to address the following, using the approaches noted.
- Conductor motion: aeolian vibration, galloping
- High mechanical loads with extreme cold
- High temperature accelerated aging
- Thermal cycling
- Fault current behavior
- Lightning strike resistance
- Corrosion behavior
- Environmental resistance: humidity, kV, temperature
- Impact resistance: ice-shedding, gunshots
After the life-aging study, the materials were then moved out into the field for testing under both conventional and accelerated operating conditions. To see a complete set of test results, see the Field & Lab Tests link.
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Q: What are the typical uses for the new conductor?
A: 3M ACCR can be used anyplace standard conductor can. However, it is best suited for applications where thermal limits are an issue. Its thermal properties and strength-to-weight ratio can solve the most difficult siting challenges, including ampacity upgrades with clearance constraints, long spans (river or canyon crossings), difficult terrain (mountains), extreme climatic conditions (corrosion or ice loading) and environmentally or politically sensitive areas (wetlands, dense population).
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Q: From a planning perspective, what does the conductor do for me?
A: 3M ACCR allows you to increase capacity across constrained areas, often without increasing voltage, allowing access to least-cost generation, while using existing towers and rights of way. This saves cost and time, reduces construction outage duration, eliminates the environmental impacts of replacing or building towers, reduces permitting and siting review and enables a more robust and reliable system in extreme operating and climate conditions.
Because of its low amount of sag, it also allows greater clearances at higher ampacity for applications such as densely populated areas, underbuilds, recreational areas, or shipping lanes, again using existing structures.
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Q: What does the conductor look like?
A: 3M ACCR looks no different than conventional conductors with specular finishes do and will not change the appearance of an existing line if installed on the same structures. Except for being slightly larger, the accessories look and install like conventional accessories, but are designed for use at higher temperatures and with the core material.
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Q: Do you have any current installations of 3M ACCR?
A: Yes. There are several field and commercial installations of 3M ACCR in a variety of applications, including areas with significant ice loading or corrosive conditions; densely populated, fast growing urban areas; and critical lines. See the section on 3M ACCR Customer Installations.
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Q: What types of conductors are available, and what are their electrical properties? (Resistance, reactance, line charging, surge impedance loading, etc.)
A: Currently 3M can supply both standard and compact conductors, in several common strandings, in sizes ranging from 300 kcmil to 1590 kcmil. Other options are available based upon the specific requirements of your transmission system and application. See Product Data and Specifications for information on the properties of 3M ACCR in some common sizes.
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