Asymptotic analysis of transient thermal field in a DC cable covered with insulation

摘要

Approximate method of determining the thermal field in a DC cable covered with insulation has been presented. The basis of the method comprises in decomposition of the system. In connection with that the two regions were considered separately. The first of them (i.e. a core) was modelled by the concentrated element of the first order. The insulation, in turn, was analysed as the element of distributed parameters type continuum RC. The adequate boundary-initial problem was solved with the aid of Duhammel's theorem and the method of separation of variables. Obtained relations were numerically processed and presented in a graphic form. The results of paper are the proof of the following thesis: on the basis of knowledge of the averaged time constant of a core it is possible to determine spatial-temporal distributions of the temperature within the whole cross-section of the system.