We always favoured technological development as a main factor to ensure competitiveness and high quality of its transformers.

An integrated Management system of all the required information for the design and manufacture of Power Transformers has been developed by Efacec.

Transformadores de Potência

Power Transformers


  • Interleaved windings, composed by rectangular coils. Coils with narrow width and a large surface. All coils are interleaved between pressboard washers with the surface in contact with the coil covered with small pressboard spacers, assuring coil cooling.
  • Rectangular shape magnetic core, composed by one single steel width and assembled in horizontal position. Core totally protected by a electrostatic shield connected to earth.
  • Upper tank (bell type), assure the compression of the core and phase(s). This particular construction assures the transportation in vertical or horizontal position.
  • Possibility of construction in dissociated phases configuration – three-phase transformer formed by 3 single-phase parts connected by a common cover, which receives the bushings and the connections between phases and the on-load tap changer.
  • Special Transformers – Phase-Shifters/Reactors (Shunt and Series)/Traction/Furnace/Rectifiers


  • Concentric windings formed by cylindrical coils of thin thickness and large surface. All the coils are insulated by pressboard barriers with pressboard spacers allowing the cooling by insulating mineral oil
  • Magnetic circuit with circular cross section is formed by vertical positioned sheets
  • The tightening structure of core and windings is designed to support the short circuit stress and to allow not only the active part untanking but also the lifting of the complete transformer
  • Special Transformers – Regulation/Traction/Furnace/Rectifiers/Reactors (Shunt and Series)
Transformadores de Distribuição

Distribution Transformers

Hermetic (Immersed)

Hermetic, mineral oil immersed three-phase distribution transformers, for indoor or outdoor installation.

PowerCast (Dry)

Cast Resin Dry Type Three-phase Distribution Transformers, commercially known as PowerCast.

Subestações Móveis

Mobile Substations

  • Reserve unit for energy supply
  • High Mobility
  • Flexibility
  • Reduced costs
  • Reduced time of delivery