Temperature aging characteristics of class a insulation

This paper reviews the literature relating to the effect of temperature on the life of class A insulation. It presents test data on aging of built-up samples 100 mils thick, of varnished cloth, both black and yellow, over the temperature range 105 to 200 degrees centigrade. The effect of temperature on the insulation was measured by three different methods — physical condition by visual observation, bending of the insulation to produce cracking, and the lowering of the breakdown voltage of samples which had been immersed in water. The final results are given in the form of temperature-time curves for several degrees of deterioration as measured by each of the tests.