“…Acoustic emission method (AE) has become one of the most commonly used methods for few decades, and known as one of the most non-invasive methods that may be applied during normal operating conditions, without having to turn off the diagnosed device -contrary to other methods, which require temporary overhaul of the tested unit (Boczar et al, 2014;Cichoń et al, 2014;Glowacz et al, 2018;Olszewska, Witos, 2012. Furthermore, it is still the only method that is fully applicable for PD localization under on-site conditions (Coenen, Tenbohlen, 2012; Kraetge et al, 2013; Mehdizadeh et al, 2013). Despite the above-mentioned advantages, AE method also has some limitations, for example: no charge calibration has been possible so far (however, research in this field has been ongoing for several years (Witos, Gacek, 2005)), relatively low sensitivity which indirectly results in quite high relative sensibility to external disturbances (compering to e.g.…”