Technical Specifications:
Hermetic transformers are designed as completely closed to the atmosphere. The internal pressure of the transformer is adjusted during oil pumping using special equipment. While the transformer is under load, it tolerates the volume expansion in the heated oil due to thermic effects, through the boiler in the wave wall structure, which has an elastic structure and also fulfills the cooling function. In order to ensure that the transformer is completely filled with oil and no air remains, oil compression is carried out in special vacuum chambers. The core and coil structure is the same as the transformer with expansion tank.

Usage Advantages:
• Since Hermetic Transformers are closed to the atmosphere, the insulation oil does not come into contact with oxygen and the insulation deterioration caused by oxidation is eliminated.
• Hermetic Transformers have a long life in terms of insulation; and therefore the service life of the transformer is extended.
• Hermetic Transformers do not require periodic maintenance other than cleaning under normal conditions and use.
• Since there is no expansion tank in Hermetic Transformers, its height decreases in terms of dimensions. This provides an advantage in substations where height is a problem.

Disadvantage over other types:
• The possibility of on-site intervention, maintenance and repair is low in Hermetic Transformers. In every case where the hermetic pressure adjustment is or will be impaired, it requires hermetic pressure adjustment with the necessary equipment under vacuum again.