Hermetically Sealed Type Transformer with Buchholz Relay 1

[sykimk]

I need your advices on the subject.
As I know, buchholz relay is generally required for protection of conservator type transformer.

However, the client spec. requires buchholz relay for hermetically sealed type transformer as well.

I wonder whether it is excessive requirement or not.
If a buchholz relay cannot be applied to hermetically sealed type transformer, then could you please give me some tips how to persuade my client?

Thanks in advance.

 

[davidbeach]

Is there a separate requirement for a Sudden Pressure Relay, or has the client used the word Buchholz where Sudden Pressure should have been used instead?

 

[waross]

Hi
See site

http://www.indubras.com.br/ingles/produto10.htm

Compare
"Sudden Pressure Relay",
"Gas Detector Buchholz Relay", and
"Gas Detector Relay".

OPERATING PRINCIPLE

The Gas Detector Buchhholz Relay is normally installed between the transformers main tank and the oil expansion tank.

If you have an oil expansion tank, you may consider a Buchholz relay.
If there is no oil expansion tank, a buchholz relay is not appropriate.

If the transformer is sealed with a gas space above the oil level consider the "Sudden Pressure Relay" that davidbeach suggests.

One of the functions of a buchholz is to detect sudden or rapid flow of oil into the conservator or oil expansion tank. If you do not have a conservator it will be challenging to install a buchholz. If you do succeed in installing it, (with a blanking flange on the conservator side, for example) it may not function.
A sudden pressure relay responds to sudden pressure.
A buchholz relay responds to sudden flow, and from that it infers sudden pressure.
I assume that your hermetically sealed transformer has a gas charge above the oil level. This will defeat the "Gas Detector" feature of the buchholz.
respectfully