On Some Imperative IEEE Standards for Usage of Natural Ester Liquids in Transformers

Abstract

From the recent past, biodegradable dielectric fluids are becoming popular across the global utilities for use in oil-filled transformers. To date, several utilities have started using biodegradable insulating fluids for new and retro-filled power and distribution transformers. The intent of this article is to compare and analyze various aspects that are involved in the successful operation and maintenance of mineral oil and ester filled transformers. The comparative analysis in this article is aimed at properties, condition monitoring, diagnostic, and reclamation aspects of ester filled transformers. The imperative and pertinent standards, including IEEE Std C57.106, IEEE Std C57.104, IEEE Std 637, IEEE Std C57.147, and IEEE Std C57.155 remain the target objectives for potential analysis. It is hoped that this critical analysis will be useful for utility and condition monitoring engineers in understanding several key aspects of ester fluids vis-à-vis traditional insulating fluids. The present analysis might also be useful for researchers and industry interested in alternative dielectric fluids for transformer insulation technology.

Use Performance and Management of Biodegradable Fluids as Transformer Insulation

“…Higher viscosity is generally a product of the interaction of esters with atmospheric air. On the other hand, the oil density and pour point is less related to the degradation and may not be helpful for the ester aging assessment purposes [42]. The oxidation stability can potentially be another parameter to evaluate the performance of the ester; however, experience shows that even using standardized methods, there is no agreement between the laboratory evaluation and the field performance of these fluids.…”

Fullers Earth Treatment for Esters Liquids used in Power Apparatuses: Inferences and Arguments

“…For this reason, companies, factories, and owners of electrical networks do not hesitate to spend many thousands of dollars on transformer maintenance and devices to protect its health integrity. Given that insulation systems in the transformers play a critical role in deciding the health index and service life of a transformer, high emphasis is laid on the transformer's insulation system [2]. In addition to protecting these important machines, the utility engineers need to have the condition of transformers assessed in order to prevent malfunction and avoid premature aging [3].…”

“…The reclamation aspects of mineral insulating liquids used in transformers and liquid-filled electrical apparatus is reported in the IEEE standard C57. 637 [2]. There is no established standard for the reclamation of ester liquids [2].…”

“…637 [2]. There is no established standard for the reclamation of ester liquids [2]. Nevertheless, various authors reported the regeneration of esters with various adsorbents.…”

“…The factory dehydration and degassing process remain the same; the treatment temperature should be around 70°C. High temperatures will influence the oxidation stability of the ester liquids and definitely have a notable impact on the weight of the available antioxidants in the bulk of the liquid [2]. To the best of the author's knowledge, this treatment temperature is not yet investigated by researchers or reported in the existing literature.…”