The faults of incomplete drying and exceeding limit often happen to the capacitive core of transformer’soil-impregnated-paper condenser bushing

which will harm safe and stable operation of electric power equipment.And these faults are usually difficult to be detected in the delivery test

acceptance test and preventive test for thebushing. In this study

the dielectric loss characteristics of the oil-impregnated-paper insulation and the thermal sta-bility of the condenser bushing were analyzed under variable temperature condition. Dielectric loss measurementand high-voltage dielectric loss test at high temperature were conducted for the bushings with damped or dry capaci-tive core

and the results verified the theoretical analysis. This test could become an effective nondestructive test fordamping fault of the oil-impregnated-paper insulation for high-voltage bushings. Test at high temperature is more ef-fective for exposing the damping fault compared with the test at ambient temperature

so it can be applied to the de-livery test. In addition

an online monitoring method for high-voltage condenser bushing was proposed based on thethermal stability of the bushing.