Preventive maintenance testing of primary XLPE underground distribution cables and the application of the .1 Hz VLF test method

VLF testing is being considered as the safe alternative to DC Hipot testing of XLPE and mixed cables because of the known problem of induced space charges, which will cause premature failures in this type of cable. The IEEE work group 400.2 is working on a recommendation regarding the VLF test methodology. The paper compares different VLF technologies and discusses the correlation between field test data and test parameters.