Diagnosis by colorimetry of aged insulating paper of transformers

The authors measured changes in the average degree of polymerization and those in the color of insulating paper. It was found that changes in the average degree of polymerization of insulating paper were closely correlated with color difference changes. This result suggests that the average degree of polymerization of the insulating paper may be estimated by colorimetry. Furthermore, the method may be applied to the insulation diagnosis of oil impregnated transformers.