Abstract :
Tests on unbleached unsized linen paper of high purity indicate that the physical defects implied by the various pyroelectric theories of insulation failure appear secondary to, and manifested as a result of, the chemical changes involved. These chemical changes result in both increased power factor and decreased dielectric strength of the insulation. The investigation shows that chemical results of overheating of cellulose insulation in service may be disastrous even within a range of temperatures not generally associated with dangerous physical effects.