Evaluation of dc insulation performance based on space-charge measurements and accelerated life tests

TLDR

Space‑charge observation is the most widely used technique for evaluating polymeric materials in DC insulation, especially high‑voltage cables, yet quantitative metrics linking the data to insulation performance are lacking. This study proposes pulsed electroacoustic test methods and parameters to assess the electrical performance of polymeric insulation under DC fields and examines their correlation with insulation life. The proposed parameters include space‑charge magnitude and mobility, internal electric‑field amplification, charge‑accumulation rate, and the threshold field for charge storage, all measured via pulsed electroacoustic technique. The paper presents examples for five candidate materials used in DC cable insulation.

Abstract

Space charge observation is becoming the most widely used technique to evaluate polymeric materials for dc insulation applications, particularly HV cables. However, quantities are still lacking that can help to summarize and interpret the huge amount of data resulting from space charge measurements, and that also are associated with the electrical performance of the insulation. The purpose of this paper is to propose test methods and parameters, based on the pulsed electroacoustic technique, which can be used for the evaluation of the electrical performance of polymeric insulation under dc fields. These parameters are related to the space charge magnitude and mobility as well as to the internal electric field amplification, the rate of charge accumulation, and the threshold field above which charge is stored in the insulation. In order to investigate the meaning of the parameters proposed for the assessment of insulation performance, the correlation between these parameters associated with space charge and insulation life is discussed. Examples are reported with reference to five different candidate materials for dc cable insulation.