Oil-paper bushing has been widely used in power system because of its good electrical and mechanical properties. Due to the influence of temperature, gravity and other factors, the moisture in the bushing is often unevenly distributed. In order to study the influence of uneven damp on the dielectric response characteristics of oil-paper insulation and realize the accurate distinction of damp types, a simulation model of uneven damp oil-paper insulation and the corresponding potential distribution model were constructed based on the basic principle of frequency domain spectroscopy (FDS) and Maxwell loss theory, and the corresponding field strength distribution characteristics were analyzed. Furthermore, two-layer stack and three-layer stack oil-paper insulation samples were prepared under laboratory conditions, and the differences and variation characteristics of the FDS curves under these two uneven damp conditions were compared and analyzed. The results show that the dielectric loss curve shows obvious loss peak and curve fluctuation when the oil-paper insulation is unevenly damped. With the increase in the number of layers, the difference between the three-layer stack and the two-layer stack increases in the low frequency band, which can be used to distinguish the types of uneven dampness.

moisture distribution;Frequency Domain Spectroscopy;oil-paper;uneven damp