Where is it used?
Like some other types of oil, such as motor oil, transformer oil’s purpose can be found in its name. This type of oil is designed for use in power transformers, which play a critical role in the energy grid. It is also called insulating oil for this reason.
What does it do?
Unlike other oils, transformer oil is not designed to reduce friction. However, it is designed to help reduce temperature – motor oil does this to an extent, as well. With that being said, this oil also has a second, even more important, task. That is, it is designed to insulate a transformer. Because of this, the oil differs greatly from other types of lubricants in terms of properties. In order to be used within a transformer, an oil must:
- Have a high dielectric strength
- Have high thermal conductivity
- Have high chemical stability
- HMust be able to maintain all characteristics at very high temperatures and for long periods of time
Transformer oil is used to preserve a the windings and core within a power transformer. Without this oil, transformers would quickly overheat and suffer damage from corona discharge, arcing, and more.
Types of Transformer Oil
Most transformer oils are mineral oil based. The two most common options on the market are paraffin-based transformer oil and naphtha-based transformer oil. Of these, naphtha oil oxidizes more easily, but the sludge produced during oxidation is more soluble than what is produced within paraffin-based oil. This means that the sludge does not collect at the bottom of the transformer where it would eventually obstruct convection circulation within the oil.
Paraffin-based transformer oil does not offer the same benefit and sludge can more easily collect at the bottom of the transformer. It also has a high pour point, which can be an issue in colder climates.
Transformer oil is primarily used in the world of power generation. However, it does have uses in other situations. It can be used in any situation in which insulation is necessary within an electrical component, and is well-suited to very high-voltage applications. For example, high-voltage switches and capacitors, as well as some types of circuit breakers can benefit from the cooling and insulating properties of this oil.
Finally, because transformer oil is a safety precaution, it must be tested regularly and replaced when its properties have been altered. On-site inspections should be conducted twice per year, and samples should be tested for dissolved gasses annually. If a transformer has been in operation for five years, the transformer oil should be subject to Furan testing every two years.