Space charge measurements in cables using the PEA method:-signal data processing considerations

Acoustic characteristics in the new cable PEA system have been analysed and it has been confirmed theoretically that the new system can provide the same sensitivity and resolution as the curved electrode system. The new system offers several advantages such as easy assembling sample, intimate contacts at the interfaces and its suitability for different sized cables. Several factors that influence the quantitative charge distribution in cable geometry such as divergence (both in pulsed electric stress and acoustic pressure) and attenuation/dispersion of the acoustic wave in thick insulation are discussed. A data processing technique has been developed which considers all of the above factors in order to improve the measurement accuracy both in sensitivity and spatial resolution. The results from the two XPLE power cables with different thermal treatments have demonstrated that the new system, together with data processing algorithms is capable of measuring space charge distribution and its change with the treatments.