Very Low Frequency HV Test of Cable Lines: an Affordable Non-Destructive Assessment of XPLE Insulation

Today, the HV withstand testing with DC or AC voltage of industrial frequency is required for all newly constructed or repaired cable lines. DC Testing of XPLE insulated cables inevitably shortened the length of service of a cable due to the formation of volume charge in the water-filled microcavities. On the other hand, the test equipment used AC voltage source of industrial frequency is expensive and difficult to operate in the field due to high capacitance of a cable line. To solve this problem, we suggest using very low frequency (VLF) test on 0.1 Hz. The advantages and disadvantages of VLF testing are compared. Additional parameters that characterize not only the performance, but also the residual life of the cable can be obtained with VLF tests are studied. These include measuring of partial discharge intensity and loss factor tan δ.