A procedure for space charge measurements in full-size HVDC extruded cables

Abstract

This paper proposes a procedure for space charge measurements in full-size HVDC extruded cables, that consists in a detailed protocol indicating voltage polarity, time intervals between measurements, volt-on and volt-off conditions, and so on. The proposed protocol accounts for the experimental practices of such kind of measurements in terms of poling time, depolarization time, heating and cooling of specimens. Such procedure seems particularly useful for assessing the space charge behaviour in terms of electric field of a cable that has undergone a prequalification test. The measurement can also give indication about the possibility of avoiding the repetition of prequalification tests and/or type tests in the case of HVDC cables, for which the Laplacian field profile cannot be taken - strictly speaking - as a reference for comparing the electrothermal stress level of new realizations with that of previously manufactured cables.