... for testing power cables, transformers, switchgear, rotating machinery and other Very Low Frequency Tester for High Voltage Cable VLF-40KVProduct DescriptionAC ... cables and electrical apparatus is now easier than ever!VLF (Very Low Frequency) Testers are suitable for testing power cables, ... PASS/FAIL AC test is the best test.By their very nature, cables will fail in installation or in service. ...