A liquid-immersed transformer is composed of a magnetic core and coil assembly immersed in a fluid, which is normally a mineral oil. The fluid must have firslty good heat transfer characteristics and secondly electrical insulating characteristics.
An benefit of a using liquid-immersed transformer is that it allows us compact design. In normal practice, transformers that are above 10 MVA and/or 34.5 kV are liquid-filled. Since oils are signifcantly flammable, the liquid-immersed transformers must be installed with adequate care and precautions according to the flammability of oil. This aspect of liquid filled transformers has put forward challenges for indoor applications.
An benefit of a using liquid-immersed transformer is that it allows us compact design. In normal practice, transformers that are above 10 MVA and/or 34.5 kV are liquid-filled. Since oils are signifcantly flammable, the liquid-immersed transformers must be installed with adequate care and precautions according to the flammability of oil. This aspect of liquid filled transformers has put forward challenges for indoor applications.
Mineral oil used in transformer insulation systems degrades if it exposed to oxygen for a long period of time. In addition to this, mineral oil has a fairly large thermal expansion co-efficient.
When talking about the disadvantages liquid transformer, several systems are applied for the purpose of minimizing degradation. Liquid-filled transformers normally protect insulating oil with one of 3 types of preservation systems:
· sealed tank system,
· nitrogen blanked, or
· conservator.
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