Estimation Accuracy of Electric Field in Cable-Insulating Wall Based on Space Charge Measurement

A method to evaluate the accuracy of space-charge measurements by estimating the electric field distribution in the insulating walls of cables is proposed in this work. Time-domain deconvolution is used to derive the stable and fully automatic processing techniques necessary to manipulate the large data required to perform the statistical analysis. The evaluation method optimizes the deconvolution parameters and analyzes the space charge waveform, which is usually only used as a reference waveform. The proposed method was validated by analyzing pulse electroacoustic waveforms obtained from a 66 kV-class extruded cable under dc voltage application. The impulse response of the observation system was optimized to provide a 95.4% confidence interval of 0.8% ± 24.1% for the waveforms, which were observed under application of a dc voltage of 30 kV. Similar estimation accuracy was confirmed for waveforms measured under application of 45 kV. Therefore, the accuracy estimated using the reference waveform can be applied to waveforms observed at high voltages that can induce both space-charge accumulation and field distortion.