Acoustic Sensor for Partial Discharges with Thermoformed Piezoelectret Technology: Calibration with the Electrical Sensor

Partial discharge (PD) is a localized electrical phenomenon that compromises the insulation of high-voltage equipment and, if left unmonitored, can lead to premature equipment failure. Reliable PD detection is essential for assessing insulation integrity within power systems. However, conventional detection methods are often costly and invasive, posing safety risks due to the required proximity to energized components. The primary objective of this study is to estimate the charge released by PD events, expressed in picocoulombs (pC), using a thermoformed piezoelectric acoustic sensor. To this end, PD signals were generated and analyzed under controlled laboratory conditions, comparing the acoustic measurements with those obtained through a conventional electrical method employing a high-frequency current transformer (HFCT). The analysis revealed a determination coefficient of r = 0.94 between the RMS values of the acoustic signals and the charge values (pC) of the electrical signals. These results confirm the sensor’s high acoustic sensitivity, enabling statistical characterization of PDs and improving high-voltage equipment monitoring. The findings contribute to advancing non-invasive monitoring techniques in electrical engineering, enhancing the accuracy of insulation degradation assessments.