High dielectric strength and long service life are important basic properties of transformers for medium and high voltage applications. Besides the least pos­sible residual moisture of the insulation (cellulose material), the dimensional accuracy of the windings is another point to focus on during production and drying.

According to state-of-the-art technology, the best and fastest process is the simultaneous hydraulic pressingduring drying in hot-air or Vapour Phase equipment. This way of proceeding significantly contributes to achieving a better quality of the windings.