English to Italian Tech/Engineering Energy / Power Generation Trasformatori

XXX is a very robust fluid and studies have demonstrated its long term stability, even at elevated temperatures.
For years, it has been successfully used worldwide in **breathing** and sealed transformer systems.

Si parla dei trasformatori per le linee elettriche. Qualcuno sa come si chiamano i trasformatori "breathing" che penso siano l'opposto dei trasformatori sigillati (sealed)? Grazie.