Recent field experience in PD assessment of power cables using oscillating voltage waveforms

The paper reports on service field experiences with PD diagnostics on distribution cables using damped oscillating voltage waveforms: This test method was introduced some years ago in particular for on-site tests. Standard test procedures using continuous AC voltages are very cost intensive due to the high capacitive power demand of the cables and the resulting large sizes of the test sets, whereas other alternative methods do not reproduce similar PD than under service conditions. Experiences from the service field reveal that the oscillating voltage waveforms (OVW) method shows a very high sensitivity of PD detection and recognition of electrical treeing. Examples for critical assessment values have been determined for cross linked polyethylene (XLPE) cables as well as for oil-paper (PILC) cables allowing the network operator to decide which maintenance operation has to be performed on the distribution cable.