Different piezoelectric structures applied to acoustic detection of impulse and corona partial discharges

Electrical discharges are frequent phenomena responsible for most breakdown failures reported in electrical distribution systems and are commonly related to the accelerated aging of equipment. Therefore, the detection of electrical discharges is important to avoid severe damage to equipment and to improve companies´ preventive maintenance. Acoustic sensors have been successfully used to monitor partial discharges (PD) in power transformers, although they are too costly for use with distribution transformers. An alternative solution to such sensors are electromechanical films (EMFi) also known as ferroelectrets or piezoelectrets, due to their frequency responses (up to hundreds of kHz), high piezoelectric d₃₃ coefficients (hundreds of pC/N) and low cost of manufacture since they are polymer-based and can be produced on large scales. Focusing on piezoelectrets and electrical discharges in this work, we present a comparative study with two different piezoelectric structures applied to impulse and corona discharge detection. From this, different waveforms from different PD were obtained and the most suitable piezoelectric configuration for detecting electrical discharges was evaluated.