Ultra-Low frequency dielectric loss measurement of high voltage submarine cable at low electric field

Abstract

As the main factor influencing 220 kV submarine power cable, thermal aging will accelerate the insulation degradation process and finally lead to insulation failure. The ultra-low frequency dielectric loss can evaluate the degree of insulation aging, and has been widely used in 10-35kV cables, but there is no further study in 220 kV submarine cables. In this work, an ultra-low frequency voltage was applied to 220 kV submarine cable. The dielectric loss can be obtained by analyzing the phase relation between voltage and current of the tested cable with the method of this work. The experimental results show that the dielectric loss tangent value is influenced by the output of ultra-low frequency power supply. The value will increase when the output voltage increases or the frequency decreases. The dielectric loss tangent increases with the increase of aging time under the same measurement voltage and frequency. Therefore, the results in this work show that the dielectric loss at low electric field has a significant relation with the thermal aging stage of submarine cable.