The transient ampacity of an overhead transmission line is a basis for load scheduling during peak period and for safe operation in an emergency.In this paper

a method for estimating the transient ampacity was presented via the transient thermal balance equation

and a computation model based on Runge-Kutta formula was proposed to avoid the error induced by coefficient of heat transfer and to ensure the accuracy of evaluation.The characteristic parameters

such as conductor’s temperature rise

transient ampacity

and remaining time

were analyzed with their calculation methods.The transient ampacity of an overhead transmission line was discussed according to the field data sampled by DLR system

and the results show that the transient ampacity of an overhead transmission line can be further developed.