The process of creeping discharge-caused damage on oil/pressboard insulation

Authors : RUIJIN LIAO, ENDE HU, LIJUN YANG, LIAN DUAN

Pages : 1434-1445

View : 13 | Download : 8

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :This paper presents experimental research on creeping discharge by using cylinder-plate electrode configurations under AC voltages. The process of creeping discharge-caused damage on the oil/pressboard insulation was studied. First, the electric field distribution was achieved by Multiphysics software simulation. Afterwards, the phenomena that occurred in the entire damage process, such as ``white smoke``, ``white mark``, and ``black mark``, were recorded and analyzed. Furthermore, the micromorphology of the oil-impregnated pressboard was observed via scanning electron microscope insert ignore into journalissuearticles values(SEM);. Finally, the inner mechanism of the damage to the oil/pressboard insulation was explored according to the phenomena and the SEM morphologies. Results showed that during damage processes, the high electrical field strength insert ignore into journalissuearticles values(nearly 25.853 MV/m); at the weak-link point between the cylinder electrode and the pressboard directly caused the incipient discharge. The cavity, moisture, impurity, solid particle, and formation of a gaseous channel all contributed to the development of the damage. The ``white smoke`` consisted of gases that stemmed from the ionization of oil and evaporation of moisture. The ``white mark`` was the gas channel and pressboard carbonization was caused by discharge and high temperature, both of which were also the main causes of the emergence of ``black mark``. SEM images revealed that the pressboard successively experienced ``white solid``, ``crack``, and ``pitting``, which changed its surface roughness. The distorted electric field caused by gases, solid particles, and pitting further damaged the oil/pressboard. The pitting evolved into the starting point of the electrical trees and gradually led to the final breakdown.
Keywords : Transformer, oil pressboard insulation, creeping discharge, damage process, COMSOL simulation, surface morphology