Study on microstructure and electrical properties of oil‐impregnated paper insulation after exposure to partial discharge

摘要

This paper studied microstructure and its relationship with electrical properties for oil‐impregnated paperninsulation during partial discharge damage process. Material analysis apparatuses such as for atomic forcenmicroscopy and X‐ray diffraction instrument, combined with electrical analysis apparatuses such as highresistancenmeter, dielectric spectra meter, and cylinder–cylinder electrodes, were employed to investigatenmolecule chain structure, aggregation state structure, permittivity, dielectric loss factor, volumenconductivity, and electrical strength of oil‐impregnated paper insulation during the damage process.nResults reveal that crystal regions of insulation paper suffer more severe damage during partial dischargendamage process compared with the amorphous regions. Crystallinity exhibits an increasing trend andncrystal grain orientation is enhanced, whereas crystal grain size, crystal type, and two‐phase‐coexistentnstructure are retained. Increased crystallinity and enhanced crystal grain orientation result in permittivity,nvolume conductivity, and dielectric loss factor decreasing, but electrical strength increasing. Changes in thenactivity of molecules, ions, and electrons are the results of variations of crystallinity and orientation; thesenare the main reasons for the change in electrical properties. Copyright © 2011 John Wiley & Sons, Ltd.