On the variability of PD results among expert independent laboratories

In spite of the fact that no evidence exist that PD amplitudes can somehow be used to estimate the expected “life” of generator components such as Roebel stator bars and multi-turn coils, certain portions of industry have assumed that pass-fail criteria based upon absolute PD amplitudes are meaningful enough to be used as pass-fail tests for Roebel bars and Multi-turn coils. In this context the present work evaluated the ability of expert independent laboratories to generate reproducible PD readings when performing PD tests on the very same set of bars.