Everything about Transformer Oils
A power transformer is an integral part of any electrical substation. It is basically your responsibility and duty in ensuring that this will stay active and working 24/7. Here in this article, we are going to talk about transformer oils and the reason to why we are using transformer oils in power transformer.
In general, the oil that we are using for electrical power transformer insulation as well as cooling purposes is referred to as insulating oil or transformer oil. This oil is then used for the collection of partial distillation of the crude petroleum. Now, there are a couple of major reasons why making use of this insulation oil among power transformers are very important. For one, transformer oils are in charge of protecting the main core as well as winding of transformers. The transformer oils additionally act as an insulation so by that, it will protect the winding from direct contact in oxygen while stopping any type of oxidation reaction.
There’s another vital point to utilize in transformer oil in power transformer. It is absorbing any excess amount of heat when transformers are operational and keeping the transformer cool from within. With this in mind, the transformer oil main functions are to cool and to insulate the transformer. With this in mind, the transformer oils should have properties similar to very high dielectric strength, thermal conductivity and at the same time, chemical stability. When it’s held at high temperatures over extended time period in transformer, then the oil should be kept in these properties.
Now when it comes to the transformer insulation types. In most cases, there are a couple of transformer oil types that are being used and these are the Naphtha Based Transformer Insulation Oil and Paraphin Based Transformer Insulation Oil.
The common specifications of these transformer oils are pour point ?30 ?C or lower, flash point 140 ?C or greater and dielectric breakdown voltage 28 kV (RMS) or greater. Because as what mentioned earlier, the main functions of a transformer oil is to insulate and to cool the transformer. In an effort to better improve the cooling effect for large power transformers, oil-filled tank might be installed with external radiators through which the oil will be able to circulate through natural convection. Believe it or not, the power transformers that have capacities of thousands kVA might have its own oil pumps, cooling fans and oil-to-water heat exchangers just to ensure that it will work as expected.
Power transformers do undergo extended drying processes by using electrical self heating and the application of vacuum or sometimes, both to make sure that the transformer is totally free from any water vapor before introducing insulating oil to it. This is a big help in preventing the formation of corona as well as the subsequent electrical breakdown under load.
The oil filled transformers with conservator or oil reservoir on the other hand might have gas detector relay to detect gas buildup inside the transformer as a result of corona discharge, internal electric arc or overheating.