Experimental study of XLPE power cable insulation detection based on the electrical capacitance tomography sensor

The XLPE cables are a vital part of power transportation. Defects in the insulation of the cable body and its accessories may lead to economic losses or safety hazards, and the current installation quality of cable terminal joints lacks effective detection methods. Since the permittivity of the cable insulation will change accordingly when there is a defect in the cable insulation, Electrical capacitance tomography (ECT) is a technique that can display the spatial distribution of permittivity of different media. In this work ECT is applied to the detection of insulation defects in XLPE cables. An eight-electrode array sensor is manufactured, and the cable capacitance is detected with an impedance meter. The cable sample sheath layer was cut into a defect area with a length of 20 mm, a width of 10 mm, and a thickness of 1 mm to simulate an air gap defect. The capacitance value of the intact cable and the defective cable is measured by the sensor and impedance analyzer, and the image of the internal structure of the cable is established using the linear back-projection algorithm. Experimental results show that ECT algorithm can detect the air gap defect in the XLPE cable insulation, but the imaging accuracy still needs to be improved.