Non-intrusive partial discharge measurements of MV switchgears

Partial discharge (PD) activity results in the degradation of insulation systems in a range of high and medium voltage equipment and if left unchecked will eventually lead to disruptive failure of the equipment. Operating MV equipment with active partial discharge increases the risk of failure occurring at the time of switching leading to increased risk to the operator. An understanding of the processes involved in the degradation of various insulation types has enabled the development of instruments capable of non-intrusively detecting PD activity. The instruments are designed to assess insulation condition by detecting the presence of PD activity while the HV or MV equipment is energized and in normal service. This paper shows how two power utility companies have successfully introduced the widespread use of PD testing, what their main drivers are behind the adoption and the practical results, experiences and benefits gained consequently.