Partial Discharge Analysis of Natural Ester Oil Based Nanofluid Impregnated Pressboard Insulation

The transformer insulation system relies on solid and liquid insulation for safe and efficient operation, directly impacting lifespan. Various nanoparticles (NPs) have been introduced in liquid insulation to enhance dielectric properties, but issues like agglomeration limit their effectiveness. To overcome this limitation of agglomeration, the NPs are impregnated on the surface of the pressboard insulation, offering stable thermal and electrical performance. It is established in the previous literature that the addition of these NPs in solid insulation will suppress the partial discharge (PD) generated but it is not been extensively studied. So, in this work, an extensive study is conducted to analyze the effect of the NPs on the suppression of PD in the pressboard insulation. In this paper, the PD analysis is carried out for natural ester oil (NEO) based nanofluid-impregnated pressboard (NFIPB) insulation. These samples are compared with mineral oil (MO) NFIPB insulation for comparison pur-poses. This study uses two types of NP: insulating -TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, and semiconducting -ZnO NPs. The pressboard samples are modified with NPs through weight-to-volume concentrations of 0.05 wt% and 0.1 wt% for TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and ZnO. Scanning electron microscopy (SEM) analyses the NP dispersion on NFIPBs. PD tests follow IEC 60270, measuring PD inception voltage (PDIV) per IEC TR 61294 and phase-resolved partial discharge (PRPD) patterns for all the NFIPB samples. The study explores the impact of NPs on PDIV and PRPD patterns, emphasizing their role in improving PD performance.