Assessment of Moisture Content in XLPE Insulation of Power Cable Using Dissipation Factor Measurements

This paper presents a technique to assess the moisture content in cross-linked polyethylene (XLPE) cable insulation through frequency domain spectroscopy (FDS). An XLPE power cable sample has been taken from a power utility company. Twenty artificial holes were created with a dimension of 0.5mm in diameter and 2.5mm in depth to simulate the moisture content in xlpe insulation. Frequency domain spectroscopy (FDS) was performed over the frequency range of 20 Hz to 10K Hz with the help of a 6500B impedance analyzer. Dissipation factors were calculated for five different cases, namely without holes, five holes (W
1
), ten holes (W
2
), fifteen holes (W
3
), and twenty holes (W
4
). Statistical parameters were calculated for five different cases, like average value and standard deviation of the dissipation factor data for assessing the moisture content in the xlpe insulation of the power cable. A clear relationship was found between moisture content (ppm) and average value as well as moisture content (ppm) and standard deviation of dissipation factor. These relationships can be modelled with suitable equations which can be useful for moisture.