/images/TDUpdate2.gif/images/southwire_100x70.jpgTemperature Sensing May Boost Transmission Revenue - 2003TempSensingMayBoostTransmissionRevenueApr2003.htmWhen profitable short-term power transport opportunities come up, you want to take advantage of them. But how much load can your transmission conductors really handle on any given day, when capacity varies with changes in air temperature and wind speed?
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Temperature Sensing May Boost Transmission Revenue - 2003

Grid capacity is based on conductor temperatures. Accurate measurements could optimize grid usage.

Nobody wants to leave money lying on the table. When profitable short-term power transport opportunities come up, you want to take advantage of them. But how much load can your transmission conductors really handle on any given day, when capacity varies with changes in air temperature and wind speed? Southwire is working to help you know.

"Southwire is exploring new conductor-temperature sensing technology that may help power grid operators know what their day-to-day capacity really is," says Gene Sanders, Southwire product development engineer. "There is a potential for large paybacks in increased grid throughput."

Embedded fiber optics sense conductor temperature

The measurement technology Southwire is exploring is called Distributed Temperature Sensing (DTS), and it uses fiber optic strands contained in the overhead conductor. By monitoring key optical fiber characteristics, grid operators can get an accurate, span-by-span temperature profile of conductor runs up to 15 miles.

"Today's grid capacity estimates are typically based on worst-case assumptions," says Sanders. "In the Southeast on a summer day, the assumption may be that the air temperature is 104°F with very little breeze. Under those conditions, a conductor might be limited to 1,000 A, for example."

But if the air temperature in the example is actually 75°F and there is some wind, 1,000 A may leave the line 40°F below its limit. Embedded-fiber technology can help identify that unused capacity while avoiding thermal overloads that might damage the conductors or violate sag limits. In conjunction with a major mid-west utility, Southwire has been testing a pilot DTS installation on a 138kV line since February of 2002 and results so far are very promising.

"We're looking forward to a time when we can optimize grid capacity with accurate conductor temperature data," says Sanders. "One day, direct measurement of conductor temperatures may be the norm. Southwire is helping it happen."