On the computation of electric field and temperature distribution in HVDC cable insulation

The paper presents certain aspects of electrical/thermal failure of dc power cables. Closed form theoretical formulations for computing the critical stress and temperature due to an external heat source in the form of a steady current through the conductor is presented. The criticality here implies an unstable state of the dielectric and is shown, more often than not, to be different, from that corresponding to thermal decomposition limits. Formulation and solution of continuity equations under first and second kind boundary conditions taking account of electric stress and temperature-dependent dc conductivity is covered. Using the suggested model, stress and temperature distribution in the body of the insulation can be obtained to a reasonable degree of accuracy.