Effects of Molecular Structure on the Physical, Chemical, and Electrical Properties of Ester‐Based Transformer Insulating Liquids

Abstract

This article presents the experimental studies carried out on the environmental friendly polyol ester insulating liquids to investigate the effect of molecular structure on the physical, chemical, and electrical properties. Six different polyol esters that can be produced from the transesterification of various methyl esters with neopentylglycol/trimethylolpropane alcohols were synthesized and compared with those of refined, bleached, and deodorized palm oil (RBDPO) and mineral transformer oil. The finding suggests that the physical properties like fire point, pour point, and viscosity are very much affected by the molecular weight and molecular composition of the polyol esters. The electrical properties are also highly influenced by the molecular structure-related characteristics, such as the polarity, dipole polarization, carbon chain length, and degree of branching. The results confirm the findings of previous studies that the polyol esters and RBDPO have more polarity and dipole polarization compared to mineral oil. The experimental evidence showed that the newly synthesized insulating liquids have favorable thermal and electrical properties, thus suggesting that the insulating liquids have the potential to replace conventional insulating liquids to provide a more sustainable power system in the future.

Investigation on micro‐mechanism of palm oil as natural ester insulating oil for overheating thermal fault analysis of transformers

“…It has been reported that eliminating H atoms on β‐C (i.e. β‐H atom) of triglyceride molecules can effectively improve the thermochemical properties of natural ester molecules [49]. Common synthetic ester insulating oils are hindered esters that lack β‐H.…”

“…The chain reaction propagates through β‐scission, which leads to C‐C bond decomposition and the formation of large quantities of small unsaturated hydrocarbons. The process of β‐scission of the C‐C bond can also activate the substrate and generate many new free radicals [49]. In addition to β‐scission, which is dominant, conjugated reactions have been observed, which are important because the reactions' products can combine with olefin compounds through Diels‐Alder reactions to produce naphthenic hydrocarbons and aromatic hydrocarbons.…”

Prospects of Plant-Based Trimethylolpropane Esters in the Biolubricant Formulation for Various Applications: A Review

“…In three reports by our group (Raof et al, 2019b;Raof et al, 2019a;Raof et al, 2019c), the high oleic TMPE was synthesized from palm oil methyl ester. We studied the effect of molecular structure on the physicochemical and electrical properties in detail.…”

“…The only drawbacks of this ester are its physical properties such as high viscosity and pour point which does not conform to the IEC standard. Thus, in a different study, we blend the TMPE with mineral oil and 80%/20% blend (TMPE/mineral oil) was found to be promising with properties nearest to the standard values for transformer liquid insulation (Raof et al, 2019c). The blend provides significant benefits to utilities in terms of improved fire safety, biodegradability, and performance properties.…”

Alternative Fluids – with a Particular Emphasis on Vegetable Oils – as Replacements of Transformer Oil: A Concise Review

“…Phosphoric esters have high fire point and permittivity. In certain aspects, such as breakdown voltage, dissipation factor and resistivity, they are supposed to be comparable or even better than mineral oil, but they tend to also have some negative aspects because they pose some environmental risks [24,41]. Because of the latter, their use is rather limited.…”