At the assembly stage, the mechanical stability of the windings plays a particularly important role.
End and tapping leads of all the windings are connected by special extra flexible, insulated copper cables, which are rigidly braced in position. In oil forced units, oil is circulated inside the winding by specially designed pipes of insulated materials.
High mechanical rigidity is achieved by hydraulic pressing at calculated force and tightening all pressure screws. The core-coil assembly is put into the oven for dehydration process.