encapsulated and open winded transformer

[vinod]

:ashamed1:We installed encapsulated dry tyoe transformers inside the building.What is the difference betwenn encapsulated and open winded transformer?
Please clarify..

 

[templdl]

A open wound transformer is where the transformer core and coil are installed in a ventolated enclosure where air is allowed to enter the enclosure toward the bottom area of the enclosure and exit out of the enclosure toward the top to cool the core and coil. The enclosure is designed such that it protects from contact of live parts.

The encapsulated transformer is a core and coil that is place into an enclosure, then it is encapasulted with a mixture of sand a resin which set. Then the end of the enclosure is installed. The transformer is essentually totally enclosued and non-ventilated. The transfomer is cooled be dicipating its heat from the surface of the enclosure.
Encapsulated transformers a generally eclusive to the smaller KVA transformers but are available to over 150kva.
There a NEMA 3R and can be 4X and 12.

 

[templdl]

A open wound transformer is where the transformer core and coil are installed in a ventilated enclosure where air is allowed to enter the enclosure toward the bottom area of the enclosure and exit out of the enclosure toward the top to cool the core and coil. The enclosure is designed such that it protects from contact of live parts.

The encapsulated transformer is a core and coil that is placed into an enclosure, then it is encapasulted with a mixture of sand and epoxy resin which sets. Then the end of the enclosure is installed. The transformer is essentually totally enclosued and non-ventilated. The transfomer is cooled be dicipating its heat from the surface of the enclosure.
Encapsulated transformers a generally eclusive to the smaller KVA transformers but are available to over 150kva.
There a NEMA 3R and can be 4X and 12.

 

[vinod]

Is there any reason to use encapsulated XMR instaed of open wound xmr?

 

[templdl]

Smaller KVA transformers may only be available in encapsulated. Having worked for a DTDT manufacturer I f ound that the cost of manufacturing them is about the same as a ventilated and, as such, you mat not have a choice but the encapsulated. As the KVA increases ventilated become less costly.

One must remember that a ventilated transformer does require periodic inspection to assure that the transformer core and coil area and ventilation opennngs are dust free so that the air flow is unobstucted.
Ventilated transformers are NEMA 1 where encapsilated are NEMA 3r.

 

[jeremysterling]

Ventilated transformers are NEMA 1...

Rainshields are used often to put ventilated XFMR's outside.

 

[templdl]

jeremysterling,

You are correct regarding the rain shields where ventilated transformers in the higher KVA sizes with weather shields are much, much less expensive than encapsulated transformers of the same KVA. In the majority of installation it is the most economical and best choice
However, it is important to note that even a ventilated transformer with weather shields is susceptible of getting packed with snow is some areas which must be considered such as Alaska. As such ventilated transformers even with weather shields may not be the best choice there.
These the encapsulated transformer is more suitable.