Superconducting Fault Current Limiter

Australians quietly develop something completely different.

A "fault" in a transmission or distribution circuit is nasty business. Circuit breakers open up, and that not only interrupts service to a lot of customers, it can also put a surge on the system. Worse, most fault clear themselves almost immediately, and then a decision has to be made, either by a person or by the equipment, whether and when to reclose the breaker. This is rough on the system, and the breakers themselves are expensive and hard to maintain.

A Fault Current Limiter (FCL) is a subtler way of dealing with momentary faults. It recognizes a sudden high current that’s not supposed to happen; it "inserts" a high impedance in the line momentarily to block that current, and returns to normal once the situation corrects itself. This is not an easy task, however. Currently (no pun), FCLs are far from ideal. Air core reactors using metallic copper conductors incur high operational losses, have limited response time, and wear out easily. What’s more, the breakers usually trip anyhow.

It’s long been recognized that FCLs are a great application for high temperature superconductors (HTSC). In fact, it’s seen as the first and best application of HTSCs on the power system. The basic idea is to put a superconducting element in the circuit in such a way that if too high a current comes along, the element goes "normal" or momentarily stops being a superconductor. This supplies the temporary high impedance to limit the current, and once the current drops, the superconductor goes back to being a superconductor and lets the current can flow again. This happens almost instantaneously, faster than a mechanical switch, and with "softer" transitions.

A SC FCL could thus detect abnormally high current transients in the grid, e.g. from lightning strikes, in a fraction of a cycle, and control the fault current so that system equipment can absorb it safely, protecting valuable downstream infrastructure.

Superconductors go "normal" if the temperature gets too high, or if the magnetic field gets too high. A SC FCL relies on the latter type of "quenching". The base current passing through the device produces a magnetic field below the level that would turn off the SC — a fault current will increase the magnetic field enough to do the trick.

SC FCLs are the subject of intense R&D efforts worldwide. ABB installed a prototype at a substation in Switzerland in 1997. The DOE is funding a new $12M program (, and EPRI is offering a major study (

A conference earlier this month presented the very latest on SC, including power applications. Note the three FCL sessions. Applied Superconductivity Conf, ASC 2004, Jacksonville, FL, October 3-8, 2004

Essentially all these efforts to date are using the bulk property of SC, and involve putting the entire load current through the SC itself, as described above. This leads to designs that are highly complex and which require a lot of SC material (i.e. very expensive wire or tape – which is proving difficult to make in large quantities). Moreover, none have progressed beyond the R&D stage and or early field beta trials. (Note – in most designs, a shunt actually supplies the impedance, not the quenched SC element, — even more complicated.)

Meanwhile, Down Under!

Meanwhile, a quiet development program in Australia has come up with a novel approach which has already been successfully demonstrated, and which is coming to North America. They developed their own SC tape and SC coils (and manufacturing method), and they invented and patented a 3-phase FCL that works in an entirely different way. It is actually more of a "controller" than a limiter of fault current.

It is a HTSC-enabled saturated magnetic core inductor. The load current passes through a copper coil on one side of a laminated-steel core. A DC coil on the other side maintains the core in a fully saturated state of magnetization. The number of copper turns are set so that a fault current in the AC coil will drive the iron core out of saturation (on the negative swing of the waveform). The coil then presents a large current controlled reactance, clipping the fault current at the design value.

All of this is explained in detail in a white paper presented in 2003, and which is available on request. Download 3.5 MB — (password required)
The design uses only a small amount of superconductor, simply to maintain the core magnetization (the only reason you need SC for this is that ordinary coils would be too big and lossy). More important, it works; it’s simple, robust, and versatile; and it will be available in a year at a reasonable price point. Key advantages include:

Superior Fault Condition Performance
– Very fast response time – protection functions activate in a fraction of a cycle.
– Large dynamic range – accommodates overloads without degradation and recovers instantly.
– Superior dynamic performance – suppresses initial transients more fully with much shorter decay times.
– Self-triggering/self-governing – operates instantly because of fundamental physical laws, no external sensing or controls required.

Low Cost
– Low operational cost – very little electrical losses in standby mode.
– High durability – very low cycle fatigue – operates through multiple operating cycles or fault events with little or no degradation.

– Expandable architecture – can be field or shop reconfigured to meet future requirements or changing grid characteristics.
– Small footprint and flexible form factor – compact to fit within space constraints and can be configured differently for local requirements.

Positive Grid Impact
– Improved grid reliability – clips fault currents completely without de-energizing the downstream grid.
– Transparency to the grid – no discernable impact during standby.

The technology has undergone substantial simulation, prototyping, and testing. The company sees no significant technical barriers and is on target to begin low-volume manufacturing and field installations of three-phase commercial units within 12 months.
The Australian company was recently acquired as a subsidiary of SC Power Systems, a US company, and operations have been moved to the US. They’ve already engaged in substantive dialogue with potential early customers and have validated the demand for its first three-phase units (15KV, nominally 10KAmps/phase).

They’ve contracted with NEETRAC (see UFTO Note 17Jan02) to prepare test procedures compatible with IEEE standards. NEETRAC member utilities are lining up to be the hosts for utility field tests scheduled for Q4, 2005. The company welcomes the opportunity to explore application needs, and will be taking orders as early as 2005.


Woody Gibson, 415-277-0179
SC Power Systems, Inc.
San Francisco, CA

The company is also raising equity funding. They presented at the NREL Industry Growth Forum, Oct. 18-20 in Orlando A business plan is available from the company.

Technology Transfer Opportunities – Oak Ridge National Laboratory



Final Report

Technology Transfer Opportunities in the Federal Laboratories

Oak Ridge National Laboratory

Oak Ridge, Tennessee

June 1998

Prepared for:

Utility Federal Technology Opportunities (UFTO)


Edward Beardsworth


Overview & Organization
Technologies & Programs

This report is part of a series examining technology opportunities at National Laboratories of possible interest to electric utilities


This report is proprietary and confidential. It is for internal use by personnel of companies that are subscribers in the UFTO multi-client program. It is not to be otherwise copied or distributed except as authorized in writing.



This report details findings about technology and technology transfer opportunities at the Oak Ridge National Laboratory that might be of strategic interest to electric utilities. It is a major update and revision materials developed previously, and is based on a visit to the lab in April 1998, and also draws from various publications, collateral information and website content.


A special note of thanks to Marilyn Brown for arranging the agenda and her gracious and tireless support, and to all the ORNL staff who gave generously of their time and attention.

Also to Mr. Scott Penfield of Technology Insights, who accompanied the visits (as a representative of one of the UFTO utilities) and kindly provided his written account of the meetings for use in the preparation this report.

ORNL — Overview & Organization

Oak Ridge National Laboratory (ORNL) is a “GOCO” lab (government-owned, contractor operated). Lockheed Martin Energy Research Corp. is the contractor that manages ORNL. (Lockheed Martin also manages the Y-12 Plant in Oak Ridge, Idaho National Engineering Lab and Sandia National Lab.)

ORNL has a matrix organizational structure, where “divisions” aligned primarily by discipline have the people, and “programs” have the projects and budgets. On some occasions, divisions do get funds and projects of their own. ORNL finds that matrix management can work well if there is a balance of power and the right incentives.

Both divisions and programs live in research “ALD’s” or Associate Laboratory Directorates, headed by Associate Lab Directors who along with other administrative and support groups report to the Laboratory Director (Alvin Trivelpiece).

ORNL’s four research ALD’s are:

=> Energy and Engineering Sciences — Gil Gilliland 423-574-9920

(Div: Engineering Technology, Fusion., Instrum & Control)

(Prog: Energy Effic/Renew Energy, Energy Technology, Fossil Energy, Nuc Technol)

=> Life Sciences and Environmental Technologies

(Div: Chemical Technol, Energy, Environmental Sci, Life Sciences)

=> Adv. Materials, Physical and Neutron Sciences

(Div: Metals & Ceramics, Physics, Solid State, Chemical/Analytical Sci . . .)

=> Computing, Robotics, and Education

(Div: Computer Science and Mathematics, Robotics and Process Systems…)

There is work in all four ALDs of potential interest to utilities. The point of contact for this study was established through the Energy Efficiency and Renewable Energy Program, which oversees activities involving 11 different research divisions. Contact was also made with the Fossil Energy Program, with a similarly broad scope. Divisions encountered include Engineering Technology, Instrumentation & Control, Metals & Ceramics, and others.

Staffing level is now at approximately 5000, of which 1500 are scientists, of which about 1/2 are PhDs. ORNL’s 1997 budget was about $550 million. Of this amount, the largest program areas were Energy Research (28%), Environmental Management (25%) and Energy Efficiency (16%). Nuclear programs, which were once the principal focus of the Laboratory, are identified at a level of 4% in the overall budget; however, when supporting research topics (e.g., High Flux Isotope Reactor (HFIR), materials, NRC Programs, etc.) are included, some $100 million can still be identified as nuclear related.

A major new initiative at ORNL is the Spallation Neutron Source facility. The 1999 budget year will constitute a major test for this project, as it will include a construction line item for the first time. If approved, construction is expected to take 6-7 years. A new ORNL directorate has been established to oversee the Spallation Neutron Source project.


Key Contacts:


Primary UFTO contact:

Energy Efficiency and Renewable Energy Program:

A.C.(Tony) Schaffhauser, Director, 423-574-4826,

Marilyn Brown, Deputy Director, 423-576-8152,

Working with ORNL:

Technology Transfer: (Licensing and CRADAs)

Dean Waters, Acting Director, Office of Technology Transfer,


Sylvester Scott, Director, Licensing, 423-576-9673,

Partnerships: (CRADAs, User Program, Personnel Exchanges, Guest Research Assignments)

Louise B. Dunlap, Director, Office of Science and Technology Partnerships,


Public Relations: Joe Culver, Director, Public Affairs,


Partnership Mechanisms

ORNL makes use of an increasingly broad array of contracting mechanisms, including CRADAs, Work for others, User Facility Agreements, etc. Greater use of simpler standard formats makes the process much quicker than in the past.

They are seeing an increasing number of “100% funds-in CRADAs” (i.e. no cost sharing by the lab) from industry, as a cheaper alternative to work-for-others with essentially equivalent intellectual property rights. The Lab also will have as many as 4000 guest assignments per year, 1/4 of which are from industry, where visitors use the facilities or work with staff on CRADAs, etc.


Energy Efficiency and Renewable Energy Program

Tony Schaffhauser, Director 423-574-4826

Marilyn Brown, Deputy Director 423-576-8152

The EE/RE Program is a matrix organization that draws on several line divisions at ORNL for the majority of its personnel and technical facility resources, to set up multi disciplinary teams. DOE is the sponsor for most of the work, but they see industry and the public as the real customer.

ORNL budget expenditures controlled through the EE/RE Program office amount to some $80 million. The ORNL Energy Efficiency/Renewable Energy (EE/RE) budget was lower in 1996, but the level now appears to be stable.

Major Research and Development Areas

=> Transportation systems, including advanced automotive technologies, advanced materials, utilization of alternative fuels including biofuels, and transportation data.

=> Efficient building systems and for state and community programs, including heating, cooling, and refrigerating equipment; roofs, walls, and foundations; insulating materials; technology transfer; and retrofit of existing residential and commercial structures.

=> Industrial processes, such as bioprocessing, electric motor systems, advanced turbine systems, advanced materials, industrial heat pumps, and evaluations of energy-related inventions.

=> Utilities, including high-temperature superconductors (for transformers and transmission cables), power transmission and distribution systems, electric and magnetic field effects, biomass for power generation, and international programs (including IEA and APEC programs).

Technologies & Programs

Superconducting Technology Program for Electric Energy Systems

Fossil Energy Technologies

Real-Time Corrosion Monitoring

Hot Gas Filters

Materials R&D

Furnace Wall Corrosion with retrofit low-NOx burners

Effects of Coal impurities on fireside corrosion

Improved Stainless Steels

“Perfect Microstructures”

Nickel-Aluminide Alloys

Sulfidation Resistant Alloys

Building Technology Center

Frostless Heat Pump

High Efficiency Refrigerator (1 kwh/day)

Power Systems Technology Program

Energy Conservation Standards for Distribution Transformers

Flywheels and Energy Storage Technologies

Utility Restructuring and Electric Power Ancillary Services

Grid Reliability-Control Center Survey

Electric and Magnetic Fields Bioeffects

Research and Public Information Dissemination (RAPID) Program

Advanced Turbine Systems

Bioenergy Program

Motor, Steam, and Compressed Air Challenge Programs

Oak Ridge Centers for Manufacturing Technology (ORCMT)

Electric Machinery Center

Power Electronics Technology Center and Inverter Technology

Instrumentation & Controls

Machine Condition Monitoring and Diagnostics

Electrical Signature Analysis (ESA) for Utility Applications

Nonlinear data analysis–Component Failure Prediction

NRC/INPO plant database

Photonics and Hybrid Lighting

Superconducting Technology Program for Electric Energy Systems

Bob Hawsey 423-574-8057

Web sites:

(See special report and series of articles on “Superconductivity in Electric Power,”

pp 18-49, IEEE Spectrum, July 1997)

The discovery of high-temperature (i.e., above the boiling temperature of liquid nitrogen) superconductor materials dates to 1986. Since that time, the challenge has been to develop these brittle, ceramic-based materials into a form that can be produced and practically used. DOE research in this area has taken a major step increase, from $19 million in 1997 to $32 million in 1998. (By comparison, Japan is investing $100 million/year in superconductor research.)

DOE HTS Program


Jim Daley, Team Leader, 202-586-1165,

or Joe Mulholland, Utility Liaison


The DOE HTS program supports a balanced technology development effort. Wire and device technologies are developed through a large number of collaborative projects between U.S. national laboratories and industry, and systems technologies are supported through the SPI and other vertically integrated project teams.

DOE’s Superconducting Partnership Initiative (SPI) is a systems technology program designed to accelerate the development of HTS electric power systems. Begun in the fall of 1993, the SPI encourages the formation of vertically integrated teams comprised of partners who usually do not interact in the development cycle, involving close collaboration among system integrators, wire and device manufacturers, end-users (typically electric utilities)

Major projects include

– 5,000 hp high-temperature superconducting (HTS) motor

– 100 MVA HTS generator,

– 115 kV and 12.5 kV HTS transmission cable (2 projects)

– 5/10 MVA HTS transformers (2 projects)

– 15 kV HTS fault current limiter (2.4 kV successfully tested in 9/95 at a utility host site)

Fault Current Limiter

Later this year, pre-commercial (alpha) prototype will be tested by So Cal Edison and Lockheed Martin. Rating is 15-kV, normal 2 kA, intercepts/reduces by 80% a 20-kA peak symmetric or 45 kA peak assymmetric fault. Also functions as a 1/2 cycle circuit breaker. If demo successful, Edison will install it at a substation, and anticipates $1million in savings from avoiding need for a second bus. Next stage will be beta units.

Contact: Eddie Leung, Lockheed Martin program manager

619-874-7945, ext. 4636,

ORNL is participating in two of these partnerships.

Transformers — There is a strong need for medium power transformers (10-150 MVA) that are smaller, more efficient and free of fire hazard, to meet the growth in urban power density. These transformers will go inside building and in multistory substations, and provide higher ratings from existing substations.

— Waukesha Electric Systems (WES), Waukesha, WI

For the Waukesha program, ORNL is responsible for the engineering, design and science of the cooling system, while Intermagnetic General is producing the HTSC coil. WES did the core, instrumentation tank, pumps and test rig. An initial 1 MVA prototype has been constructed and entered testing at WES in February 1998. Initial results are good–the first operational US HTSC transformer easily sustains 2X overloads. Rochester Gas & Electric (RG&E) and Rensselaer Polytechnic Institute (RPI) participated in this initial demonstration.

The next step will be a 5 MVA system, which will provide power to the WES plant beginning in 1999. A larger utility advisory group is participating in this second step (includes several UFTO members). The initial commercial target is a transformer in the range of 10-30 MVA.

Contact: Pat Sullivan, VP Marketing, Waukesha, 414-547-0121, x 1531.

There is a separate transformer development effort that involves ABB, EdF, Los Alamos National Lab (LANL) and American Superconductor.

Cable — HTSC Cables hold the promise of far greater capacity– 5X the power in the same 8″ diameter pipe of conventional buried cable, and without the losses, heat, oil and range limitations.

— Southwire,Carrolton, GA

The Southwire HTSC cable project is expected to culminate in an initial demonstration at Southwire in 1999. The planned 100 ft, 3-phase, 12.4 kV, 1250 Amp cable will provide power (30 MVA) to Southwire facilities. Southern Co, Georgia Transmission Co, and So Cal Edison are partners. DOE is providing half of the $14 million. Southwire has built a 200 ft clean room manufacturing facility, and recently delivered a 5 meter test cable to ORNL for testing.

Pirelli and Los Alamos are pursuing a parallel HTSC cable initiative, with participation by Detroit Edison. The initial objective is a 25 kV line.

Other HTSC development initiatives mentioned include motors/generators (including flywheel motors/generators under development at Boeing) and kaolin magnetic separation equipment being developed by Dupont for the paper industry.

NOTE- More uility participation is needed–to provide advice, and as partners, cofunders and beta test hosts. Any kind of innovative proposal is more than welcome.

RABiTS (TM) Process for Coated High-Temperature Superconductors

Oak Ridge researchers have produced a roll-textured, buffered metal, superconducting tape with a critical current density of 300,000 amperes per square centimeter in liquid nitrogen, which may pave the way for the future manufacture of practical yttrium- or thallium-based conductors for electric power applications.

To produce a superconducting wire sample, the ORNL researchers first developed a process called rolling-assisted biaxial textured substrates, or RABiTS(TM), which enables the superconducting materials to have a high degree of grain alignment in all directions, a necessary condition for more efficient current flow through the superconductor.

MicroCoating Technologies (MCT) in Atlanta and ORNL announced on April 16 that MCT has licensed key patents. “MCT scientists within a six-month period have successfully deposited both HTS coatings and oxide “buffer layers” on several single crystal oxide substrates. MCT also successfully deposited buffer layer on textured nickel. The epitaxy of some buffer layers is as good or better than with any other deposition technique to date. In addition, MCT’s open atmosphere process can meet or exceed industry-wide cost targets to enable commercial-scale production of superconductor technology.”

Other licensees include Midwest Superconductivity and Oxford Superconducting Technology, with two more pending.

Fossil Energy Technologies

Rod Judkins 423-574-4572

ORNL described some additional advancements in materials and technology for fossil and related applications that were not addressed in the ORNL survey of utilities (developed by Technology Insights and sent to UFTO members in mid 1997). Some examples are:

Real-Time Corrosion Monitoring: A flash of laser light is impinged on a fossil boiler wall. By observing the infrared response of the area, corrosion related effects, such as thinning, debonding and delamination can be inferred.

Hot Gas Filters: In partnership with manufacturers, ORNL has developed two distinct classes of hot gas clean up filters.

– A ceramic composite (SiC-based) filter developed with 3-M is primarily targeted to fluidized bed combustion applications. The filter has been tested in AEP’s Tidd Plant and a Studvik incinerator in S. Carolina. It is available through 3-M. Contact Ed Fisher, 612-736-1005

– A lower temperature (700 – 1000 deg C) iron-aluminide filter, with high resistance to sulfidation, has been developed in partnership with Pall Corp. (Portland NY) and is nearing commercial introduction. An alternative to ceramics, it can be made with standard manufacturing equipment. Tests at the University of Cinncinnati show excellent corrosion resistance. Coal gasification is the target application.

Materials R&D

Ron Bradley 423-574-6095

Ian Wright, 423-574-4451

Furnace Wall Corrosion with retrofit low-NOx burners — root cause is flame licking walls, so that control of flame characteristics using sensor-feedback arrangements should be the best solution. Hence, there is a need to develop sensors to monitor flame condition as input to control mechanism. ORNL has approaches for this, using chaos theory to analyse the flame signatures, for instance (Stuart Daw, David Schoenwald). There will also be a continuing practical need for diagnostics, coatings, repair techniques, etc., since not all boilers will be amenable to combustion control, and the use of multiple and varying coal sources will lead to continuing corrosion problems in some parts of the furnace wall. Sulfidation-resistant ferritic alloys (ORNL’s iron aluminides) promising as overlay/cladding, but difficult to apply reproducibly. Development program with Lehigh Univ-utility boiler consortium (Prof. Arnie Marder) is showing good promise.

Effects of Coal impurities on fireside corrosion — Chlorine limits based on fundamental misunderstanding–only a problem when other combustion problems (flame impingement) present. Developing in situ probes to measure short-term corrosion.