IEEE 738-1993

The purpose of this standard is to present a method of calculating the current-temperature relationship of bare overhead conductors. Conductor surface temperatures are a function of a) Conductor material properties b) Conductor diameter c) Conductor surface conditions d) Ambient weather conditions e) Conductor electrical current The first two of these properties are specific chemical and physical properties. The third may vary with time, and that variation is dependent upon ambient atmospheric conditions other than weather. The fourth, weather, varies greatly with the hour and season. The fifth, conductor electrical current, may be constant or may vary with power system loading, generation dispatch, and other factors.

Revision Standard - Superseded. A simplified method of calculating the current-temperature relationship of bare overhead lines, given the weather conditions, is presented. Along with a mathematical method, sources of the values to be used in the calculation are indicated. This standard does not undertake to list actual temperature-ampacity relationships for a large number of conductors in a large number of conditions.