The practical comparison of conductor operating temperatures against IEEE and CIGRE ampacity calculations

The maximum operating temperatures of energized conductors denotes the current carrying capacity. Historically, power utilities have used deterministic and probabilistic methods to calculate the thermal rating and operating temperature of conductors. By determining operating temperatures accurately the efficiency of overhead transmission lines can be increased and utilized closer to their thermal limits. Generally, conductor ampacity calculations are based on IEEE and CIGRE ampacity standards. Heat balance equations are used to determine the heat gain and heat loss of conductors. This paper reviews the practical implementation of measuring conductor operating temperature by means of installed temperature sensors and simultaneously comparing measured values against the values determined by IEEE Std 738-2006 and CIGRE brochure 207 ampacity calculations.