MV/LV Dry Type Transformers

A distinctive element of the dry transformer is the fact that the magnetic circuit and the windings are not immersed in an insulating liquid.

It could be MV/LV, MV/MV, or LV/LV with cast coils or resin impregnated coils.

Cast Resin Transformer:

• The MV coil - cast in resin
• The LV coil - cast or impregnated in resin.

Definition impregnated in resin (in-air transformer)

• The MV coil - impregnated in resin
• The LV coil - impregnated in resin

The core is made of high magnetic permeability grain-oriented electrical sheet, with with a 45 degree cut and intercalated step lap joints method. Alternatively, it could be of amorphous type, and which is a crystalline structure that guarantees extremely low losses, up to 4 times lower compared to the standard grain oriented solution.

The MV windings are made with fully automatic machines which insulate the wire or strip, either aluminium or copper, with class F or H insulation materials. The MV windings can be impregnated in polyester resin or cast in epoxy resin. The epoxy resin is loaded with aluminium, silicone and other additives that modify the mechanical characteristics and the TG (transition temperature). This guarantees to meet the most severe climate and environmental classes such as: low temperatures down to -60°C or high temperatures up to +60°C, and any other saline high condensation environment or environment with high pollution as required by the regulations in force for some types of application.

The LV windings are made of aluminium or copper foil or strip, insulated with class F or H materials and vacuum pressure impregnated with class H high cementing polyester resin that gives the coil excellent insulation and mechanical sealing. For special applications the insulation used is the pre-impregnated type and on request can be cast on an epoxy resin mould. The terminals are automatically welded for the whole length of the winding, to provide easy accessibility and high mechanical resistance to electrodynamic stresses.

All steelwork is of GBE production and is galvanised to allow installation in even the most aggressive environments. For some installations, the transformer can be equipped with IP protective box required for indoors or outdoors.

Therefore, GBE production are suitable for installations in hospitals, banks, public and residential buildings, and also on ships, galleries, subways and offshore platforms.