A Power Cable Thermal Aging Insulation Resistance Degradation Model

An Insulation Resistance (IR) degradation model for a power cable under thermal aging conditions is developed. The power cable insulation is constructed from the combination of a number of small segments. Segment types are classified into two types - degraded and non-degraded according to a previously published Dichotomy model. The ratio (${\mathrm {V}}_{\mathrm{d}}$ of the volume of degraded segments to the total cable insulation volume is evaluated as a function of aging time and aging temperature where ${\mathrm {V}}_{\mathrm{d}}$ degradation is determined using the cumulative distribution function (CDF) of an exponential distribution and the Arrhenius Model. The total resistances of the power cable insulation is evaluated by summing the resistances of all segments. The relationship between the size of segments and the calculated volume IR as a function of time is investigated to establish the sensitivity of the model as a function of segment size.