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# IEEE 738

## Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors

inactive
 Organization: IEEE Publication Date: 17 June 1993 Status: inactive Page Count: 50
##### scope:

Introduction

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 property may vary with time, and that variation is dependent upon ambient atmospheric conditions other than weather. The fourth property, weather, varies greatly with the hour and season. The fifth property, conductor electrical current, may be constant or may vary with power system loading, generation dispatch, and other factors.

The equations relating electrical current to conductor temperature may be used in either of the following two ways:

- To calculate the conductor temperature when the electrical current is known

- To calculate the current that yields a given maximum allowable conductor temperature

For the purposes of this standard, either the electrical current is assumed constant for all time or it is assumed to undergo a step change from an initial current to a final current. The ambient weather conditions are assumed to be constant with time in both the steady-state and transient calculation methods described in this standard.

This standard includes mathematical methods and indicates sources of the values to be used in the calculation of conductor temperatures and conductor thermal ratings. However, because there is a great diversity of weather conditions and operating circumstances for which conductor temperatures and/or thermal ratings must be calculated, the standard does not undertake to list actual temperature-current relationships for specific conductors or weather conditions. Each user must make his or her own assessment of which weather data and conductor characteristics best pertain to his or her area or particular transmission line.

The calculation methods in this standard are also valid for the calculation of conductor temperature under fault conditions.

### Document History

October 19, 2012
Calculating the Current-Temperature Relationship of Bare Overhead Conductors
The standard describes a numerical method by which the core and surface temperatures of a bare stranded overhead conductor are related to the steady or time-varying electrical current and weather...
November 16, 2006
Standard for Calculating the Current-Temperature of Bare Overhead Conductors
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 the following:...
IEEE 738
June 17, 1993
Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors
Introduction 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...
January 1, 1986
STANDARD FOR CALCULATION OF BARE OVERHEAD CONDUCTOR TEMPERATURE AND AMPACITY UNDER STEADY-STATE CONDITIONS
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