Field correlation between electromagnetic and high flux stator core tests

In stator core interlamination insulation fault tests, there is a commonplace expectation that the Quad signal detected by EL CID is correlated to the high flux test, at the rate of 5-10°C/100 mA. Evidence to date has been supportive but inconclusive. A new opportunity has been taken to review 106 reported core fault test results from the field on turbo and hydro-generators, where both tests were conducted on the same fault. A number of normalisation corrections were proposed and applied, which resulted in the population mean trend correlation lying between 8.5-10.7°C/100 mA with a 95% confidence factor. The central quartiles embrace the 6-12°C/100 mA range, close to the expected rate.