On the significance of PD measurements in liquids

This paper presents experimental data and calculations concerning the measurement of partial discharges (PDs) in mineral oil. The influence of the RLC measuring impedance is studied. The investigations were done using either signals of simple shapes or real PD signals. PDs were produced with a point-plane gap in air and in mineral oil. The discharge currents in air are integrated by the usual RLC whereas in mineral oil the charge is strongly underestimated.