Analysis of EL CID - High Flux test field correlation

In stator core tests, there has been a long-standing expectation that the Quad signal detected by EL CID is correlated to the high flux test, at the rate of 5-10 °C/100mA for faults. Limited experimental and survey work has provided some evidence for this premise, but remained inconclusive. A new opportunity has been take to review 106 reported core fault test results for both 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/100mA with a 95% confidence factor. The upper and lower quartiles embrace only a 6-12 °C/100mA range, thus falling close to the expected region. There was some evidence though not conclusive that hydro-generators have a slightly higher 95% confidence correlation than turbo-generators at 9.8-12.9 °C/100mA.