The aging characteristics of the Nomex paper for the flameproof dry-type transformer

The insulation system of a flameproof dry-type transformer under the combined thermal, electrical, mechanical, and environmental stresses undergoes gradual deterioration, which ultimately leads to transformer failure. It is hence important to test the aging characteristics of the Nomex insulation paper (aramid paper) which is the main insulation material of the flameproof dry-type transformer. In the paper, thermal and electrical aging of aramid paper specimens was performed, and during which the DP (degree of polymerization) of aramid paper specimens were measured, periodically. The experiment result indicate that DP of aramid paper specimens dramatically declines with the thermal and electrical aging time. And the microstate observation result indicate that the mechanism of the thermal aging and electrical aging for the aramid paper is different.