A study on ionization potential and electron trap of vegetable insulating oil related to streamer inception and propagation

作者：Li, Jian^*; Wang, Yachao; Wang, Feipeng^*; Liang, Suning; Lin, Xiang; Chen, Xiuping; Zhou, Jinghan

来源：Physics Letters, Section A: General, Atomic and Solid State Physics , 2017, 381(44): 3732-3738.

DOI：10.1016/j.physleta.2017.09.037

• Vegetable insulating oil
• Streamer
• Ionization potential
• Electron affinity
• Electron trap
• Density functional theory

Vegetable oils, mainly composed of triacylglycerol molecules, have been widely studied as new insulation materials in the recent years. In this work, we study the electronic properties of various triacylglycerol molecules with different degree of unsaturation by density functional theory (DFT). The ionization potential (IP), electron affinity (EA), and electron trap are estimated by theoretical analysis and experiments. The results show that the C atoms of cis C=C double bond make the primary contribution to the highest occupied molecular orbital (HOMO) of unsaturated triacylglycerol molecule; the IPs of fully unsaturated triacylglycerol molecules are almost confined to the narrow ranges from 7.30 to 7.45 eV in gas-phase and from 6.77 to 6.84 eV in liquid-phase correspond to LnLnLn and 000 molecules, respectively; the atoms of ester group and neighboring atoms make the primary contribution to the lowest unoccupied molecular orbital (LUMO) of both saturated and unsaturated triacylglycerol molecules; the EAs of triacylglycerol molecules are confined to the narrow ranges from -0.34 to -0.18 eV and the chemical trap is estimated to be 0-0.16 eV; the total trap is 0.32-0.36 eV. The IP distribution character and shallow trap feature maybe the main causes that vegetable oils demonstrate a low resistance against the fast streamers. The work can provide theoretical basis to molecular modification for performance improvement of vegetable insulating oils.

• 出版日期2017-11-29
• 单位重庆大学