Exhibition of an ageing criterion based on partial detection for Medium Voltage equipment

Electrical failure prevention is a major issue for industry. In the field of medium voltage equipment, the determination of the state of health of this type of equipment and the evaluation of the time to failure, are very important. Partial discharge detection can be efficient to reach this objective. The acoustic and more precisely the ultrasonic method is a promising method for online, non-destructive and non-intrusive analysis. Thanks to this method, it is easier to reject the external noise on site; above all, measurements can be performed on in-service equipment. This paper presents the results of two experiments carried out on a dry Medium Voltage transformer enduring highly accelerated life testing. The studied partial discharges are surface partial discharges. The relationship between the acoustic energy emitted by these partial discharges and the ageing is investigated. It is shown that an ageing criterion can be derived from the observation of the evolution of an external acoustic signal.