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This guide describes VLF withstand and other diagnostic tests and the measurements that are performed in the field on service-aged shielded medium and high-voltage cables rated 5 kV through 69 kV with extruded and laminated insulation. VLF test methods utilize ac signals at frequencies less than 1 Hz. The most commonly used, commercially available, VLF test frequency is 0.1 Hz. Whenever possible, cable systems are treated in a similar manner to individual cables. Tables are included of the recommended test voltage levels for installation, acceptance, and maintenance tests.
This guide is intended to provide troubleshooting and testing personnel with information to test shielded medium- and high-voltage cable systems rated 5 kV through 69 kV using VLF ac techniques.
Revision Standard - Active. Very low frequency (VLF) withstand and other diagnostic tests and measurements that are performed using VLF energization in the field on shielded power cable systems are described in this guide. Whenever possible, cable systems are treated in a similar manner to individual cables. Tables are included as an aid to identifying the effectiveness of the VLF ac voltage test for various cable system insulation problems.