Experimental Analysis of Aged XLPE Cable Using Return Voltage Measurement

XLPE cables are widely used for underground power transmission and distribution. Therefore, condition assessment of cable insulation is important. In this work, Return Voltage Measurement (RVM) is carried out to diagnose and characterise temperature - humidity aged XLPE cable insulation. The XLPE insulation is aged under constant stress and cyclic stress. The effect of both temperature and humidity is considered while ageing the samples. It is observed that return voltage characteristics change with ageing conditions. The measured parameters i.e. maximum return voltage, time to reach maximum return voltage and slope of the rise of return voltage are recorded. The calculated parameters i.e. p - factor and reliability factor are obtained using MATLAB curve fitting tool. Both the measured and calculated parameters is seen to change with ageing conditions. With ageing, the parameter values decrease compared to unaged XLPE. Therefore, the measured and calculated parameters can be used as ageing marker. Also, it is observed that percentage of relative humidity plays an important role on ageing.