• Standard: manufactured with an oil conservator that enables the volume variation in oil, minimizing the oil-air surface contact. The air exchange with the atmosphere is done though an oil conservator that uses silica gel as hygroscopic agent. These transformers can be manufactured either with conventional radiators or corrugated wall panels.


• Hermetic: these work under variable pressure depending on the oil's temperature, with no need of interaction with outside air avoiding the oxidation of the cooling liquid and the corresponding periodic oil analysis.
  They require only minimum maintenance.

       Hermetically sealed transformers: also known as Compact Transformers; these           transformers are fully filled with oil, with an exclusive constructive system that absorbs the           cooling liquid's dilation by means of the expansion of its corrugated tank walls.
         Nitrogen Chamber: oil dilation is absorbed by the nitrogen chamber.