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Output from a real-time sag, tension, and ampacity program was compared with measurements collected on an outdoor test span. The test site included a laser range-finder, load cells, and weather station. A fiber optic distributed temperature sensing system was routed along the conductor and thermocouples were attached to the conductor's surface. Nearly 40 million data points were statistically compared with the computer output. The program provided results with a 95% confidence interval for conductor temperatures within 10°C and sags within 0.3 m for a conductor temperature of 75°C. Test data were also used to determine the accuracy of the IEEE Standard 738 models. The computer program and the Standard 738 transient model gave comparable temperatures for temperatures up to 160°C. Measured temperatures were used to estimate the radial and axial temperature gradients in the ACSR conductor. The effect of insulators and instrumentation attached to the conductor on the local conductor temperature was determined. The real-time rating program is an alternative to installing instrumentation on the conductor for measuring tension, sag, or temperature. The program avoids the problems of installing and maintaining expensive instrumentation on the conductor, and it will provide accurate information on the conductor's temperature and ground clearance in real-time.
Date of Publication: July 2010