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| Superconductivity at STI |
Since its formation in 1987, STI has pioneered the development of HTS materials and manufacturing processes, developing more than 100 patents as well as proprietary trade secrets and know-how. Over the last decade, STI has deployed over 6,000 HTS filter systems operating today in public wireless networks, thereby proving the commercial and economic viability of HTS technology. Now, STI is applying its proven and proprietary deposition techniques and manufacturing experience to the development of cost effective, high performance 2G HTS wire for applications ranging from AC Power Cables to Superconducting Fault Current Limiters (SFCL) and HTS Motors and Generators.
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| What is Superconductivity? |
Superconductivity is a phenomenon where some materials exhibit no electrical resistance below certain cryogenic temperatures. This effect was first observed in mercury in 1911 at the University of Leiden in the laboratory of H. Kamerlingh Onnes, the first person to liquefy helium and reach temperatures as low as 1.7 Kelvin (K) (or minus 271.3 degrees C or minus 458 degrees F). From the initial discovery until 1987, development was largely based on materials at 4K and was characterized as Low Temperature Superconductors or LTS. In 1987, materials were developed which could exhibit superconducting properties at temperatures as high as 90K. This is still very cold, but it was a breakthrough because these materials could be cooled by liquid nitrogen which is much easier to work with and is considerably cheaper than liquid helium. This class of materials was called High Temperature Superconductors or HTS.
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 HTS vs. Copper:
When stacked up against a comparable copper wire based electric machine, future superconducting motors and generators could potentially offer a 2-3x size reduction with higher efficiency - thereby reducing volume and weight, which both translate directly into cost savings. |
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| How Does HTS Wire Compare to Copper? |
Most power applications today rely on copper wire to conduct electricity. However, with the rapid progress of HTS technology in the last decade, superconducting wire promises to become a viable copper alternative for advanced power systems. Second Generation (2G) HTS wire carries more than one hundred times the current of an equivalent size of copper wire and also has zero resistance to direct current electricity. These attributes can translate into significant reductions of cost, size and weight for motors, generators, and power cables.
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| First Generation (1G) vs. Second Generation (2G) HTS Wire |
| First generation (1G) HTS Wire has been commercially available since late 1990s. 1G HTS wire is prepared through a powder-in-tube process, embedded in a non-superconducting matrix, such as a silver alloy somewhat similar to the way traditional wire of copper or aluminum is made. 1G HTS wire uses a filamentary structure similar to Low Temperature Superconducting (LTS) wire. This design is inherently costly because of its reliance on using large amounts of silver. |
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Companies that currently produce 1G HTS Wire are migrating to Second Generation (2G) HTS Wire because of its superior performance in a magnetic field and improved mechanical properties, and lower potential cost. 2G HTS Wire is designed to be able to replace 1G HTS Wire in form, fit, and function, with expectations to surpass 1G wire in electrical performance and overall economics. It is fabricated through a completely different process. 2G HTS wire consists of depositing HTS materials layers onto a thin, flat, metal substrate. The HTS wire essentially looks like tape – a thin, narrow strip of metal. Thus, it requires no powder or rods to be bundled with other rods, as does 1G HTS Wire, and has the potential to be highly cost effective to produce. In addition, the HTS industry made another very significant decision to use YBCO as the preferred HTS compound. STI has been developing and producing HTS products using YBCO and other HTS materials for over 15 years to best align cost and performance.
Today, HTS wire producers are challenged to scale their 2G HTS wire manufacturing capacity to meet industry volume, cost and performance requirements. STI's 2G HTS wire product roadmap is on track to aggressively address each of these challenges.
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| Information sources on HTS Technology: |
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Brian Moeckly and Vladimir Matias (HTS Program Peer Review, June 30, 2010) |
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Brian Moeckly and Vladimir Matias. (STI Presentation, November 23, 2009) |
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Brian Moeckly and Vladimir Matias (HTS Program Peer Review, August 5, 2009) |
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Navigant Consulting, Inc. (HTS Peer Review, August 4, 2009) |
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Navigant Consulting, Inc. (HTS Peer Review, July 29, 2008) |
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Navigant Consulting, Inc. (HTS Peer Review, July 25, 2006) |
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Los Alamos National Laboratory Website |
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Wikipedia Website |
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