Dehydration is done by circulating the transformer oil through columns with granular synthetic adsorbents that attract water molecules and permanently bonding them to the active surface within the pores. By this procedure, the insulating oil is dried in a few hours or days. However, the drying of cellulose insulation is a far slower process.

By maintaining an imbalance of moisture content between oil and cellulose, with continuous oil drying, water diffusion from wet cellulose insulation to dried oil is achieved, thus removing moisture from deeper layers of solid insulation.

99 % of water in power transformer is stored in cellulose insulation
1 % of water is in the oil

Preventive maintenance
Corrective maintenance

Field of Application

New or previously dried power transformers- continual maintenance of low moisture level in both oil and cellulose insulation. 

Transformers with increased content of moisture – reduction of moisture in complete insulation, improvement of insulation characteristics, increase of power transformers safety and its lifetime