Optimizing palm oil insulation with rice husk powder: A mechanistic study of breakdown voltage enhancement

Siti Sarah Junian; Sebastian Dayou; Mohamad Zul Hilmey Makmud; Jedol Dayou.

This study investigates the enhancement of breakdown voltage (BDV) in palm oil (PO) insulation by varying concentrations of rice husk (RH), aiming to address the mechanisms responsible for its performance optimization. Dielectric (real permittivity and loss tangent) and physicochemical tests were conducted. At low RH concentrations (up to 0.20 g/L), well-dispersed RH particles effectively reduce dielectric loss tangent to a minimum of 0.0083 and moderately decrease real permittivity due to optimal charge trapping and improvement of homogenized electric fields. Beyond 0.50 g/L, particle agglomeration becomes dominant, leading to a sharp increase in both real permittivity and loss tangent, degrading BDV performance due to interfacial polarization and increased conduction paths. The inverted U-shaped viscosity trend shows a transition from stable RH dispersion to agglomeration. While moisture content was also analyzed, moisture scavenging was not identified as a dominant mechanism. UV-Vis spectroscopy confirms the presence and varying concentrations of RH particles. This research provides mechanistic insights into the interplay between filler concentration, dispersion quality, and electrical properties, which highlights the importance of dispersion control for optimizing natural ester-based insulating fluids. This study is unique in demonstrating how the U-shaped trends of real permittivity and loss tangent mirror the inverted U-shaped BDV curve, suggesting a common mechanistic foundation for optimizing natural ester-based insulating fluids.

KEYWORDS: Breakdown voltage; Loss tangent; Natural esters; Palm oil (PO); Real permittivity.



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