Diagnostic markers for AC power cable insulation aging based on space charge measurements

The results of space charge measurements carried out on specimens cut from high-voltage XLPE cables are discussed in this paper. The specimens were aged in the laboratory under electrical, thermal and thermoelectrical stresses, for various times, with the purpose of searching for diagnostic indicators derived from space charge data. It is shown that two quantities extracted from space charge measurements, that is, the threshold for space charge accumulation and the apparent, trap-controlled, mobility display a good correlation with aging time and stress, thus providing interesting markers for aging diagnosis and life estimation. Aging models are proposed correlating markers with aging time.