Each basic unit is built up with a number of elements. The elements are wound with a high-grade specially biaxially oriented, hazy polypropylene film. High purity aluminium foil is used as a conductor between the polypropylene layers. The element assemblies are given adequate outside insulation. These are put in an all welded M.S. container. These containers are surface-treated so as to make them rust free. The containers are put in a vacuum chamber where they are simultaneously heated, dried and degassed so as to reach very high vacuums. While they are still under vacuum, they are impregnated with a special grade of capacitor oil. This oil is bio-degradable and thus constitutes no hazard to environment. The impregnated units are taken out, sealed and tested.

They are then degreased and painted. The painting system consists of phosphetising, a primer coat and two coats of enamel paint.

Externally, each unit has two separate earthing points, nameplate confirming to the requirements of IS-2834, discharge resistances and finally HRC fuses of adequate rating: