Natural ester insulating oil possesses advantages such as a high flash point and inherent biodegradability. However

their molecular structures contain unsaturated C=C bonds and β—H functional groups

making them prone to oxidative degradation and stray gas generation. Currently

there is limited research on effective methods to suppress gas evolution in these materials. To address this challenge

this study proposes a component regulation strategy by introducing trimethylolpropane nonanoate (TMPN) to mitigate gas generation in natural ester (NE). TMPN was synthesized via vacuum esterification

and a series of TMPN-NE blends with varying TMPN concentrations were prepared and characterized. An electro-thermal-flow multi-field coupling experimental platform was constructed to investigate the gas generation behavior of the modified oil. Simultaneously

the AMS software was employed to construct composite models of NE and TMPN-NE systems. The mechanism of gas suppression at the molecular level was elucidated by calculating the diffusion coefficient of oxygen atoms. Experimental results indicate that the addition of 3% TMPN yields the most effective gas inhibition performance. The calculation results show that the oxygen diffusion coefficient in the TMPN-NE system is approximately 5% lower than that in NE

primarily due to the steric hindrance introduced by the TMPN structure. This study provides critical insights into the suppression mechanisms of gas formation in natural ester insulating oil

offering a theoretical support and practical guidance for promoting the long-term and stable operation of power equipment.