Assessing Retrofilled Ester Fluids’ Impact on Mitigating Sulfur Corrosion in Power Transformers

This study examines the effectiveness of different ester fluids (PFAE, FR3, and MIDEL 7131) in preventing sulfur corrosion in power transformers. Through the utilization of techniques such as Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), X-ray Fluorescence Spectroscopy (XRF), tensile strength measurements, and surface resistivity measurements, the degradation of paper and liquid insulations in retrofilled transformers due to sulfur corrosion is assessed. The findings revealed that sulfur corrosion results in the formation of copper sulfide, which degrades paper insulation, leading to decreased tensile strength and surface resistivity values. Notably, retrofilling with PFAE demonstrated a sulfur intensity reduction of 99.57 %, significantly outperforming MIDEL 7131 at 96.02 % and FR3 at 91.61 %, compared to mineral oil’s 80.87 %. SEM-EDX and XRF techniques provided valuable insights into the chemical composition and elemental analysis of the insulation materials, aiding the understanding of sulfur corrosion. The findings of this study are relevant to various transformer types operating under comparable conditions, highlighting the importance of cu