Detection of water trees in medium voltage cables by RVM, without reference measurements

Measurement of the polarization spectrum by Recovery Voltage Measurement (RVM) is one among several methods, which are proposed in the literature to characterize the state of deterioration of water-treed cable insulation. It has previously been shown that it is possible to use RVM for detection of water trees in PE and XLPE cables. In this paper the authors present a methodology that allows the detection of water trees at low DC test voltage without the need for a reference measurement. This methodology makes use of a so called division spectrum, which is obtained from the results of two separate recordings of the polarization spectrum.