Study on Calibration Method for Space Charge Measurement by Pulsed Electro-acoustic Method

In solid insulation systems, the space charge generated by the insulator under a high DC electric field is one of the factors determining the properties of the insulation material, and its measurement has become an indispensable method of evaluating insulation materials. As one of the common measurement methods of space charge, the pulsed electroacoustic (PEA) method detects the time-domain acoustic signals generated by the interaction of the space charge with the pulsed electric field through a piezoelectric transducer, and thus the position and value of the space charge are deduced. Recently, measurements utilizing the PEA method have become a reality for ultra-high voltage DC insulation systems such as full-size DC cables. However, the spike noise generated by the high-voltage pulses applied during the measurement process can lead to fluctuations in the offset and tilt of the baseline of the response signal, which can lead to errors in the measurement and analysis results. For the measurement of thick specimens, it is difficult to eliminate this effect due to the small response signal. In this paper, the method for minimizing this error is discussed using the measurement results of a parallel plate electrode insulation system as an example.