303kV/7.2 kV station service transformer

[jacob13]

How to get auxiliary power for 500kV switchyard which does not have any transformer - just breakers and disconnects? Can we buy 300kV/7.2kV, ~300KVA single phase transformers? Any another ideas will be appreciated.

 

[rcw retired EE]

Bring in another service from the local utility distribution system. If necessary for reliability, back it up with a small diesel generator. That was the cost effective solution for one of our clients.

 

[prc]

The problem we cannot make a 500KV 300KVA power tarnsformer is the minimum conductor size required.Minimum rating will be atleast 20 MVA to get mechanically reliable HV winding. Otherwise it will become a voltage transformer.It is not good to compromise the integrity of 500 kV circuit by means of such a small unit feeding station.

 

[FPelec]

Jacob13,
In the utility I work with, when MV supply is not available nearby, we use small SF6 transformers with nominal voltages 400 kV /0.4 kV and rated power 125 kVA (single phase unit). Actually, as prc said, they look more alike to voltage transformers rather than power transformers. Note that they can include a disconnector inside the "tank".
You can find attached a brochure from one major manufacturer; I'm sorry but i didn't manage to find it in English.


Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[bacon4life]

Looks like they make several different models:

http://search.abb.com/library/Downl...LanguageCode=en&DocumentPartId=&Action=Launch

 

[jacob13]

Thanks for the information, bit they do not have 500kV voltage class.