Usually, any liquid filled transformer will need oil or liquid in order to cool, while dry type transformers will only use high-temperature insulation systems which can be environmentally safer.
In the dry type transformers, there will be no moving parts, and hence such transformateur à sec which in English is called as dry transformer will need minimal maintenance.
Therefore, you can find its application in schools, hospitals, chemical plants, factories and buildings where safety against fire is vital.
You can easily install them indoors and also outdoors where there is sufficient ventilation.
There is one drawback and that is it can be easily influenced by dust, dirt, moisture or corrosion as its windings are usually exposed to air. So, you need to periodically clean to prevent any build up of dust and any other contaminants over some time.
What are the various types of dry transformers?
Many different construction methods are employed to manufacture various types of dry transformers, based on different kinds of environment and also based on their applications you will find many types of dry transformers. Few of them are as follows:
- Open wound transformers
You can find such transformers for indoor uses where the conductor coils will be pre-heated and after that further heated. Then they are dipped in varnish at a higher temperature.
In order to cure varnish, coils will be baked by using dip-and-bake method.
- Vacuum pressure impregnated transformers
Vacuum pressure impregnated transformers usually are constructed by using high-temperature insulation that will have high-temperature materials that is coated with moisture-resistant, high-temperature and polyester sealants by employing vacuum impregnation process.
- Vacuum pressure encapsulated transformers
Similar to the above transformers, where polyester sealant will be replaced by certain resin made out of silicone. In order to manufacture these transformers several dip processes are involved, which is followed by curing of the coating in an oven.
These transformers are very high resistant to humid or caustic environment and also various effects of saline water.
- Cast-coil resin transformers
These transformers are quite reliable and are exposed to various extreme conditions and need minimum amount of maintenance. They can also withstand any kind of short circuits.
Due to this reason cast-coil resin transformers can now be used where only liquid-filled units earlier were available particularly for harsh environments. You can find their applications in ships, tunnels, nuclear plants and cranes and mining industries.
Whatever may be your application, there are all types of transformers available which includes medical isolation, toroidal, power transformers, 3-phase transformers, SMPS and audio line matching etc.