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Insulation structures based on cellulosic materials and mineral oil have been the standard solution for transformers for the last hundred years, both in distribution and power transformers. These structures typically consist of a solid-liquid arrangement, aimed to divide larger voltage drops in smaller steps, creating small volumes of liquid with high dielectric insulating performance and reaching...
Natural ester liquids are increasingly established in power transformers, especially if the water protection and prevention of fire hazard in operation region of transformer are in focus. They show a comparable dielectric strength to mineral oil in homogeneous and slightly inhomogeneous fields. Nevertheless, differences exist between natural ester liquids and mineral oils in terms of electrical properties...
The design of feasible insulation for converter transformers requires the understanding of field distributions in insulating materials, which are normally a combination of oil and cellulose-based materials. The AC field distributions within the insulation system depend on permittivities of materials. Contrary to AC field distribution, DC field stresses are determined by conductivities of the insulating...
HVDC equipment is normally stressed with AC, DC and super-imposed stresses during its operation time. Contrary to AC field distribution, DC field stresses are determined by the conductivity of the insulating materials, which consist of insulating liquid and cellulose-based transformer board. As a result, a deep knowledge of the permittivity and conductivity of barrier-oil insulation materials are...
Using natural ester liquids as insulation material in power transformers offers many advantages compared to conventional mineral oils. There are, for example, higher flash and fire point, greater water solubility, and better environmental sustainability. Despite several studies confirmed the equivalent dielectric capacity for the typical construction elements of transformers, some studies representing...
Natural ester liquids as insulation material in power transformers offer many advantages compared to conventional mineral oils. Some have, for example, higher thermal capacity, higher flash/fire points and better environmental sustainability. Despite several studies confirmed the equivalent dielectric capacity for the typical construction elements of transformers, some studies representing extremely...
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