Here is most of the text of a summary prepared by the developers, Com Ed and Southwire. The complete Word document with graphics can be downloaded at:
http://www.ufto.com/clients-only/fotc.doc (password needed)

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**ComEd – Southwire Alliance Develops Novel Fiber Optic Transmission Conductor (FOTC)

In 1999, ComEd began work with Southwire to investigate a new concept to accurately determine the thermal behavior of overhead transmission lines during operation. It is the conductor temperature that dictates the thermal rating and available clearance under a line. However, as of yet no satisfactory method has been developed that measures conductor temperature axially throughout its length as well as radially.

A novel overhead transmission conductor system that uses optical fibers as an integral part of the phase conductor has been developed by ComEd and Southwire (Patent Pending) and placed in service on the ComEd system.

Operational since February 21, 2002, the 138 kV FOTC system uses distributed temperature sensing (DTS) to measure the temperature of the optical fibers that are embedded in the conductor. DTS allows accurate temperature measurement along the entire length of the FOTC line at different locations within the conductor.

Prior to the field demo, the FOTC system was tested and characterized by the NEETRAC {see UFTO Note, 17Jan02} and Oak Ridge National Lab (ORNL). Significant discoveries on the temperature behavior of the transmission conductor under various test conditions were found. For example, the impact of wind on radial temperature drop across a conductor and the impact of solar radiation on a conductor varied significantly from IEEE Std 738 during extreme weather conditions.

Field Trial Installation: The Fiber Optic Transmission Conductor (FOTC) was installed using a special dead-end assembly and an optical insulator. The installation method was the same as a conventional one, except that special care was taken to separate and protect the optical fibers from the conductor at the dead-end location.

The graph shows an example of the temperature data that is available in real-time from the FOTC system. With the FOTC system it is a simple matter to show the temperature of any desired interval lengths of the FOTC line. [graphic: Temperature versus Time Profile of 138 kV FOTC Line]

Utilities have a need to maximize the use of their assets. FOTC provides the medium for utilities to determine the real-time thermal operating limit of a transmission conductor in the most accurate way possible. It also provides the means to transmit data or voice communications. As the utility industry continues to evolve through transmission open access, new innovations such as FOTC will help pave the way to competitive advantage.

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Southwire will pursue the development and commercialization of FOTC under a license from ComEd. A market study is underway, and in particular the partners want to learn more about how much FOTC can increase transmission capacity, and how utilities will judge the merits and value for use on their own systems.

Contacts for Additional Information
Jim Crane, ComEd, 630-576-7034, james.crane@exeloncorp.com
Gene Sanders, Southwire, 770-832-4988, gene_sanders@southwire.com