Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems. Группа авторов
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СКАЧАТЬ live conductors. Insulation oil (traditionally, mineral insulating oil) is used preliminarily for insulation of the core. The main functions of the insulation oil in an oil‐filled transformer are as follows:

       Oil acts as an insulating medium: Provides insulation for the conductors.

       Oil serves as a coolant by dissipating internally generated heat: Heat dissipation is done in conduction, convection, and radiation modes with the help of solid insulation and cooling tubes.

       Oil acts as a diagnostic medium for prognosis of aging characterization of in‐service oil‐filled transformers: Small volume of the liquid is collected from the transformer to test according to the standards for diagnosis and prognosis in understanding the situations prevailing in the transformer (similar to blood in human body).

       Oil acts as a barrier to the laminated sheet steel core by preventing direct contact with atmospheric air.

      Mineral insulating oils extracted from crude petroleum are being used in transformers successively since decades. However, due to various technical demands/benefits, health/safety aspects, and environmental concerns, alternatives for mineral oils are of high demand by the industry. There is a need to shift the transformer insulation technology to a suitable new alternative and biodegradable liquids. Ester‐based dielectric fluids, both natural and synthetic fluids, have been subjected to extensive research since decades. The performance of these new insulating liquids is found to be affirmative and comparable to mineral insulation oils. Despite their overwhelming technical benefits, very few utilities started using these alternative insulating fluids. One of the reasons includes the availability of limited diagnostic and prognostic information in the existing knowledge. The reclamation aspects and service experience of these new insulating liquids also remain as a pertinent challenge for the utilities.

      Liquid insulation in transformers plays a critical role in assessing the lifetime of a transformer. Useful life of a transformer relies on the electrical health and effectiveness of insulating oil. Owing to prevalent thermal conditions within an in‐service oil‐filled transformer, the performance of solid insulation paper, pressboard, etc., and the effectiveness of the insulating oil to serve as an insulator and as a coolant, reduces significantly over a period. High thermal excursions in the transformer tend to accelerate the aging process of the oil–paper insulation. Eventually, insulation paper degrades by releasing certain gases, moisture, furan‐based compounds, and suspended particles percolating into the insulation oil; thus, enhances the deterioration of oil. As per ASTM D117‐18 [20] standard, commonly adapted parameters of insulation oil to monitor the transformers are classified as electrical, physical, and chemical.