Oil filled transformers without conservators or oil level gauges

[edison123]

I have attached two drawings of a 750 KVA and a 2000 KVA, 6.6 KV/415 V oil-filled "sealed-for-life" transformers with a pressure relief valve with electrical contacts (?) on the top. The OEM claims that these trafos are sealed for life and do not require conservators or oil filling valve or oil level indicator.

Is there any standard that specs these type of conservator-less trafos ?

Muthu

http://www.edison.co.in

 

[edison123]

Also, these trafos do not have a nitrogen blanket on top. OEM claims these are hermetically sealed trafos.

Muthu

http://www.edison.co.in

 

[Marmite]

Areva has a range of hermetically sealed transformers, as do several other manufacturers. I think they can be built in accordance with any of the usual specs, DIN, IEC60076 etc.

http://www.areva-td.fr/solutions/liblocal/docs/Products/30314_Level3_v2_loRes.pdf

Regards
Marmite

 

[edison123]

Thanks Marmite. I am learning about this type of trafos. Seems to be of recent origin. They claim the radiators expand under load to accommodate the oil expansion. My question is wouldn't that sideways expansion drop oil level in the tank.

Muthu

http://www.edison.co.in

 

[rasevskii]

A similar type of trafo was made by Schorch of Germany. The Oil was slightly pressurized by a device on the top of the tank using a spring-loaded piston in a cylinder. That was 10 years ago. Not sure if they still are being made.

regards, rasevskii

 

[jghrist]

In the USA, standard padmount distribution (MV-LV) transformers are sealed construction without conservators. There are filling and draining provisions, however, and an oil-level gauge.

See IEEE/ANSI C57.12.26, Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers for Use with Separable Insulated High Voltage Connectors, High Voltage, 34 500 Grd Y/19 920 Volts and Below; 2500 KVA and Smaller, Requirements

 

[edison123]

Thanks rasevskii and jghrist. Unfortunately I do not have that standard. oddly, these transformers have oil draining outlets but appear to have no filling points. Also, is an oil level gauge a must for a hermetically sealed trafo ?

Muthu

http://www.edison.co.in