When three-core cable in distribution system needs to load larger emergency loads for other line fault or power repair

the time the cable can resist the overload is an urgent issue for cable running and monitoring department.The 10 kV three-core cable is taken as the research object in this paper.Firstly

a cable transient thermal circuit model is established

and the transient temperature rise of the cable is divided into two parts

the steady state component and five transient components including different thermal time constant.Secondly

by means of the method of data fitting

the parameters of different transient components are determined

then the calculation formula of cable emergency time is obtained under the action of emergency loads.Finally

the transient temperature rising experiments are designed under different emergency loads.The experimental results show that

using the proposed method the emergency time of cable can be calculated accurately

which provides the basis for the emergency capability evaluation of the three-core cable and power emergency dispatching.