Insights on the criteria of selection of vegetable and mineral dielectric fluids used in power transformers on the basis of their biodegradability and toxicity assessments

Abstract

Leakage of transformer dielectric fluids is a concern because it may pose a risk of environmental contamination. In this study, the deleterious effects of vegetable and mineral dielectric fluids in water bodies were investigated using biodegradability and acute toxicity tests with Danio rerio and Artemia salina. Regarding biodegradability, all four tested vegetable oils (soy, canola, sunflower and crambe) were considered as easily biodegradable, presenting degradation rates significantly higher than the Lubrax-type mineral fluid. Acute toxicity tests were performed in two separate experiments without solution renewal. In the first experiment, the organisms were exposed in direct contact to different concentrations of vegetable (soy) and mineral (Lubrax) oils. Total soy-type vegetable oil has a higher toxic effect than Lubrax-type mineral oil. In the second experiment, the organisms were exposed to increasing percentages of the water-soluble fraction (WSF) of both types of tested oils. The LC values for the water-soluble fraction of the Lubrax-type mineral oil were about 5 and 8% for the Danio rerio and Artemia salina bioindicators, respectively, whereas the vegetable oil did not present toxic effect, regardless of its WSF. These results have shown that a strict selection of dielectric fluids and monitoring the leakage from power transformers is a serious duty of environmental protection agencies.

Transformer mineral oil ingestion induces systemic sub-acute toxicity in Wistar rats

“…Transformer mineral oil (TMO) is reportedly not easily oxidized and is heat stable and so can withstand repeated heating for a long time (Modenes et al., 2018). Due to these properties that are considered desirable, some local Kenyan fried food vendors use it to blend cooking edible oils.…”

“…Transformer mineral oil (TMO) is a clear liquid with an odour of petroleum. It is used as insulating oil in transformers because it is stable at high temperatures (Modenes et al., 2018). Crude oil or petroleum has always been the primary source of TMO.…”

Oxidative Stability of Soybean Oil under Accelerated Transformer Conditions: Comprehensive Mechanistic Studies

“…Currently, versatile insulating oils are extensively employed in different electronic facilities, for example, transformers, and in most cases, these insulating oils are traditionally produced from the mineral oils . In view of the scarcity of the fossil feedstock and the environmental concerns about the leaking of the mineral oil based insulating oils due to their poor biodegradability, exploring biomass-based insulating oils has been attracting much attention because of their sustainability, excellent biodegradability, low toxicity, low flammability, etc. , …”

“…1 In view of the scarcity of the fossil feedstock and the environmental concerns about the leaking of the mineral oil based insulating oils due to their poor biodegradability, exploring biomass-based insulating oils has been attracting much attention because of their sustainability, excellent biodegradability, low toxicity, low flammability, etc. 2,3 However, exploring biomass-based insulating oils also faces some challenges that are related to their chemical compositions. In general, biomass-based insulating oils come from versatile vegetable oils, that is, natural esters, which are the mixtures of different glyceryl esters.…”