Impulse Breakdown Characteristics of Transformer Oil with Cellulose Particles in Quasi-Uniform Field

This study presents an experimental comparison of the breakdown characteristics of oil samples with four cellulose particle content levels in a quasi-uniform electric field under lightning impulse voltage. For the experiment to resemble the actual working conditions of transformers and meet the on-site withstand impulse voltage test requirements, both the standard lightning voltage (SLI) and oscillating lightning impulse (OLI) are considered. The experimental results show that an increase in the number of cellulose particles directly weakens the oil insulation strength. At the same particle content level, the oil breakdown voltage under OLI is higher than that under SLI, and the breakdown time lag under OLI is longer than that under SLI. The breakdown time lag is more sensitive to the effect of particle content under SLI. This work is beneficial in deepening the understanding of the impulse breakdown characteristics of transformer oil within cellulose particles and in providing references for the on-site impulse test of oil-immersed power transformers.