Calculation of sensitivity requirements for rapid measurement of insulation deterioration rates

This paper will provide calculated estimates of the sensitivity needed for several methods used to indicate slow-insulation deterioration. The sensitive methods particularly considered are gas product chemical analysis (gas chromatographic or mass spectral), gravimetric, and differential thermal analysis (DTA). The question of the magnitude of the effects with slow reactions at lower temperatures and the limitation on rate measurements with such methods will be considered. Extension of such measurements from accelerated high temperatures, where deterioration is relatively rapid, down to lower temperatures nearer to apparatus operating temperatures, gives promise of more rapid determination of insulation life—providing such results can be correlated with functional performance. The calculation is based on known or published chemical heats of reaction and decomposition rates at elevated temperatures, and extrapolation of such data to lower temperatures. Possible sources of error and interpretation of results will be considered.