EREA dry power transformer
There are two types of transformer configurations:
- Dry transformers
- Immersed or oil-filled transformers
These transformers are composed of coils wrapped in an epoxy resin without intermediate liquid, which allows them to withstand thermal shocks well. The presence of epoxy resin prevents dielectric leakage and the risk of fire or explosion. The coating allows them to be resistant to external agents such as dust and humidity.
These transformers require little to no maintenance. They are also more environmentally friendly than immersed transformers.
These transformers are designed for indoor installations. For example in shopping malls, hotels, industry or high-rise buildings. Some countries make the installation of this type of transformer mandatory for all high-rise buildings.
Immersed transformers, also called oil-filled transformers, are immersed in a liquid which is either mineral oil from petroleum or, as a more ecological alternative, vegetable oil from plants. This liquid is used as a dielectric.
These liquids are flammable, so a number of safety devices such as a DMCR or DGPT2 protective relay must be used when operating them.
These transformers are suitable for indoor and outdoor installations. Unlike dry transformers, due to the presence of flammable liquids this type of transformer requires protection against fire risks. There are therefore installation constraints. For example, they are not permitted in high-rise buildings.