Two-dimensional Space Charge Measurement in Cable Joint Model Using the Pulsed Electroacoustic Method

This study discusses the space charge measurement in a scaled cable joint model as a move towards its application to full-scale HVDC cable joints. A prototype of the improved PEA cell is created using a high-sensitivity PEA cell with polymer acoustic coupler combined with a 16-channel piezoelectric sensor array. The measurement employs Pulsed Electro-acoustic (PEA) method on HVDC cable joint model with 6.6mm thick XLPE cable insulation and 11mm thick EPDM joint insulation. The feasibility of the PEA cell with a 16-channel sensor array was examined by applying a pulse voltage to the shield layer of the joint box and maintaining the cable screen at ground potential. The measurements obtained from 16-channels were deconvolved considering acoustic divergence, pulse field intensity and acoustic attenuation. The PEA cell dedicated to joints allowed the recording of interfacial charge buildup near to the triple junction at the deflector in a 2-D cross sectional profile.