​​​Overhead line designers typically assume the conductor temperature is homogeneous through the thickness of a conductor and use the surface temperature to calculate the sag of a line. If the core temperature of the conductor is significantly hotter than the surface temperature, then this assumption is invalid and the lines will sag more than predicted. Thus, it is important and useful to know if this core-to-surface exists and if it is large enough to affect the sag calculations. In this project, NEETRAC conducted experimental studies to evaluate the effects of a wide number of factors (current, tension, conductor type, aluminum area, percent steel and odd/even layers) on the core-to-surface temperature differences of conductors. This research was a follow-on to an earlier report on an initial small sample size and diversity of constructions.

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