Identification of Multiple Defects in Solid Insulation Using Combined RF and IEC60270 Measurement

Using an integrated measurement system, partial discharge activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio-frequency (RF) pulse energy and the apparent charge measured according to IEC60270. Plotting the energy of the RF pulses against the corresponding apparent charge produces a correlation that will be sensitive to the shape of the underlying current pulse, which would be expected to vary depending on the type and severity of the defect. This paper presents combined measurements for several resin insulation samples containing a number of voids of known dimensions. Results indicate that using a combined measurement strategy, it may be possible to discriminate between discharge activity occurring in each void based on the correlation between apparent charge and RF energy.