Principals and field experience with the 0.1 Hz VLF method regarding the test of medium voltage distribution cables

The IEEE standards group is currently addressing the topic of field testing methods for underground power cables. The first step has been accomplished by issuing the IEEE 400 document, which is also referred to as the Omnibus document and serves as the umbrella for all field test methods to be covered under individual standards or user guides within the 400 series of documents. The IEEE 400.1 document will become the new test document covering all field DC test methods. The IEEE 400.2 will address very low frequency AC field test methods, also referred to as VLF test methods. VLF testing is being considered as the safe alternative to DC Hipot testing of XLPE and mixed cables, which will cause premature failures in this type of cable because of the known problem of induced space charges. The paper compares different VLF technologies and discusses the correlation between field test data and test parameters.