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Hermetic power transformers

Hermetically sealed power transformers are ideally suited for the harsh environment of offshore platforms.

They have neither a conservator, nor any dehydrating breather. Oil expansion is absorbed by the specially-designed tank and radiators. Moreover, the onload tap changer, when used, is fitted with vacuum contact chambers which prevents oil decomposition due to the switching operation.


  • Substantially longer service life
  • Reduced maintenance thanks to lower oil ageing, no dehydrating breather and no hydro-compensator


  • Up to 245 kV, 200 MVA or 170 kV, 250 MVA

Engineered - Hermetik Transfo in plant - 136MVA 123-11kV ONAF