A new accelerated aging procedure for cable life tests

Abstract

A new accelerated aging procedure for cable life tests has been proposed in this paper. The objective has been to minimize the total test costs using cable samples subject to the constraint that all relavant cable characteristics should be preserved by the samples. The procedure utilizes a combined approach based on available physical and mathematical models and laboratory accelerated aging tests. The behavior of dielectric strength, dielectric loss angle, capacitance and loss of mass in XLPE cable models subjected to different aging conditions (voltages and temperatures) has been monitored in order to verify the proposed procedure. Investigations have proven that the results concerning aging effects obtained under combined stresses (simultaneously electrical and thermal) are different from those obtained under single-stress aging. The degradations caused by combined stresses cannot be directly related to the changes caused by the single stress, i.e. their superposition is not valid. It has been found that tan delta can serve as a representative indicator of other cable properties relevant to aging phenomena.