A new thermal rating approach: The real time thermal rating system for strategic overhead conductor transmission lines -- Part II: Steady state thermal rating program

Abstract

The elements of the steady state thermal rating program are described which includes how the convective heat transfer from overhead conductors is affected by wind turbulence, wind direction, velocity profile (a function of height above ground, temperature lapse rate, and type of terrain), conductor surface type (stranded or smooth), conductor pitch, and the proximity of conductors in a bundle configuration. Equations are developed for the thermal conductivity and the kinematic viscosity of air. It is also shown how the conductor temperature may be solved directly by formulating a biquadratic equation rather than utilizing an iterative procedure.