Condition assessment of HV cable based on broadband dielectric spectroscopy

In this paper, the broadband dielectric spectroscopy (BDS) method is applied to different service aged, 110 kV cables samples, to obtain their permittivity and tan delta under a frequency range from 0.1Hz to 107Hz. The service time of the service aged samples vary from 1 to 27 years. In particular, the permittivity and tan delta under 0.1 Hz and 50 Hz were analyzed to support the field test and on-site diagnostics. The results of service aged XLPE slices show that tan delta and the imaginary part of relative permittivity increased obviously after 15 years operation and the trend is more obvious as the duration of service increases, whilst the real part experienced little change. In order to apply this study to condition assessment of in-service cables, a set of revised criteria is proposed based on analysis of 0.1 Hz tan delta and IEEE standard 400.2 recommended values.