Influence of Partial Discharge on Dissipation Factor Measurement at Very Low Frequency

For diagnostic assessment of electrical insulation in high voltage power equipment, partial discharge (PD) and tanδ (DDF) measurements are the most popular methods. In this paper, an experimental study to investigate the influence of partial discharge on DDF measurement is presented. Laboratory measurements were carried out on a service-aged 11-kV XLPE cable which had insulation defect. Sinusoidal voltage was applied at very low frequency (0.1 Hz) and at power frequency (50 Hz). Measurement results reveal that diagnostic characteristics such as discharge magnitude and repetition rate are strongly dependent on the excitation frequency and have a considerable influence on the tan-delta measurement.