Effect of Metal Oxide Nanoparticles on the Breakdown Voltage of Transformer Oil Containing Cellulose Particles

Failures are sometimes attributed to the deterioration of insulating oil, with contamination by cellulose particles. Such contamination lowers the dielectric strength of the oil. This study investigates the effect of cellulose contamination on the impulse breakdown voltage of transformer oil and evaluates the potential of nanofluids as a remediation strategy. A controlled amount of cellulose particles is added and dispersed into mineral oil at a concentration of 0.02 g/L to simulate a contaminated oil sample. Titanium dioxide (TiO₂) and aluminum oxide (Al₂O₃) nanoparticles are then dispersed into the contaminated oil at concentrations of 0.02 and 0.04 g/L. Impulse breakdown voltage is measured under both positive and negative polarities using electrode gaps of 1 mm and 2.5 mm, while dielectric permittivity is also measured to assess polarization effects. The influence of nanoparticle type and concentration is analyzed considering relaxation time and electron scavenging mechanisms. The results show that cellulose contamination markedly reduces dielectric strength, whereas the addition of nanoparticles effectively restores and, in several cases, enhances the insulating properties beyond those of uncontaminated oil.