82 / 2022-03-11 12:21:31

Partial Discharge Inhibition Effect of the Al2O3/PTFE Functional Film Fabricated on the Insulating Pressboard

partial discharge,Oil paper insulation,functional film,power transformers,Nano-dielectrics

Oil-impregnated pressboard is widely used as an electrical insulation medium in power transformer. During the manufacturing process, the existence of defects in the insulating pressboard is inevitable. These defects may induce partial discharge (PD) within the transformer under high voltage, which could result in deterioration in materials and even lead to the final breakdown. At present, many researches have been focused on the PD phenomena of the oil-paper insulation, consisting in unveiling the PD characteristic of oil-paper under AC, DC and AC-DC combined voltage. However, rare research lay emphasis on the modification of the pressboard to inhibit PD and decrease the damage caused by PD. Currently, the technology of interface property tailoring becomes popular among the material modification methods. Compared with the method of nano-particle or micro-particle doping, surface modification owns the advantage in having little impact on the bulk property of the material. It is of great significance to find the novel surface modification method to suppress PD in oil-paper system. In this paper a functional composite film composed of Al₂O₃ and PTFE layers is deposited on the surface of the insulating pressboard by radio frequency (RF) magnetron sputtering. The PD characteristic of the sputtered and the untreated pressboard is tested under fixed AC and DC voltage respectively for comparison. The PRPD spectra under AC voltage and the parameters of the discharge quantities as well as time interval between two discharges under DC voltage are showed. SEM images show that the damage caused by PD on the sputtered pressboard surface is decreased owing to the functional layer. In addition, thermal aging test results show that the functional layer is thermal stable and still works after aging at 393K for 30 days. The functional layer could inhibit the development of PD and reduced the damage caused by PD in the pressboard. The functional layer is thermal stable and still works after aging. Al₂O₃/PTFE functional film was successfully fabricated on pressboard surface by magnetron sputtering. This film could inhibit the development of PD in oil-paper system. This research displays a novel way to enhance the insulation performance of the oil-impregnated paper.