Vacuum Pressure Impregnated (VPI) Transformers

VPI transformers, a new construction concept, are suitable for installations that require particular attention to the environment, with minimum flammable material.

The windings up to 1.1kV class are made in foil or strip in a continuous layer; for higher voltages, the winding is made of disks connected in series or parallel according to the voltage or power of the winding.

The insulation can be used in class F or H and the impregnation is made with class H polyester resin

All production with air insulation has a small amount of flammable material, less of the resin solution and without any term of comparison with the oil solutions.

The transformer impregnated in air is not only suitable for distribution, but also for any type of special applications (such as the resin transformer). There are no particular limitations for the insulation levels, although generally it is not used for classes higher than 36 KV.

This type of transformers can be provided with a protective box, according to the desired IP. The boxes are painted with epoxy paint according to the RAL requested (RAL standard 7032) with pickled or galvanised sheet for outdoor installations.

Special applications for the outdoors include the creation of an aluminium box complete with MV ceramic bushing and LV resin insulators.