A test technician’s toolbox can never have too many options. The more ways we can detect or confirm a problem in a piece of equipment, the better. Early in my career at Duke Energy, I was never satisfied with just one test result indicating a problem, and I often second-guessed myself as to whether the equipment was bad or if …
To explain VLF tan delta, we must first explain the reason it was developed and how the concept and equipment used to perform this test came about. Tan delta is still a form of high-potential (hipot) testing but utilizes the advantages of both AC and DC testing while eliminating many, but not all, of the disadvantages. The very-low-frequency (VLF) portion …