We stand for the highest quality in technological development and recognized Worldwide as a reference designer and european manufacturer for power transformers, distribution tranformers and mobile substations, ensuring every solution is eficiente and competitive.

In 2020 we launched an innovative modular system concept for power equipment, which allows the same equipment to receive new features at the pace of customer needs. With the international patent “Modular system for applications in transformers No. PCT/IB2020/052435”, we respond to the market and customers’ needs, redefining the product placement methodology, based on a concept of system modularity.

The new concept will be applied to Efacec’s Core Power Transformers. It is estimated that in 2022 about 55% of the Core Transformers produced by Efacec will have incorporated this innovation and in 2023 all transformers of this type will be produced following this concept.

Our innovative modular system concept was recently awarded with the Red Dot Award, an award that recognizes outstanding industrial design of the 2021 year.

Transformadores de Potência

Power Transformers



Windings & Coils | Composed by a small number of copper coils interleaved with pressboard washers in a vertical position inside the transformer. Rectangular shape with rounded internal and external corners. High surface and narrow width. The LV and HV windings are interleaved to reach the ideal arrangement, which means the optimization of the short-circuit forces, losses and hot-spot temperature.

Pressboard Washers | The outside and the inside of the coils are covered with molded pressboard components to assure the required dielectric strength either between coils or between coils and core.

Phase Assembly | The phases are firstly installed in the lower tank compressed against the tank wall, before the core assembly. The upper tank is then assembled, assuring the compression of the core and phases.


  • Very good voltage distribution across the winding, due to the natural high series capacitance – excellent behavior to the fast transients (lightning impulses, switching impulses)
  • Minor DGA evolution along transformer life cycle
  • High resistance to short-circuits
  • Higher flexibility (vertical or horizontal position) both for shipping and for operation
  • Modular design option: dissociated phases configuration


  • 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


  • International patent “Modular system for applications in transformers No. PCT/IB2020/052435

  • The modular character is evident in the assembly and disassembly processes, which provides greater safety and ergonomics in the manufacture, transportation, installation and maintenance of the equipment
  • The reduction achieved in the equipment weight and size (more compact) allows to minimize the costs and complexity of transport logistics, as well as minimizing the ecological footprint, particularly in urban environments. It should be noted that all the elements that make up the transformer are recycled at the end of its useful life
  • With this concept, transformers will be prepared for the era of digitalization and 4.0. industry, allowing them to explore new features and applications in the digital management of networks and equipment
  • The modular system will be applied in equipment from 10MVA to 170MVA and up to 400kV and includes a range of innovative solutions in the architecture and assembly of external components, adding new functions, such as mechanical protection, noise, ultraviolet and ballistics, which improve the performance, durability and reliability of the product in the most diverse applications, whether urban or in extreme environments.
Subestações Móveis

Mobile Substations


  • To provide a solution to quickly replace the need for a power transformer/ substation, either complete or partially
  • The fastest recovery in the distribution/ transmission grid, either with all the equipment installed in the same trailer or with the equipment splitted by different trailers
  • The final design will always be a tailor-made solution, matching the customer requirements and its modus operandi


  • Emergency operation (seismic, outages, fire, floods, war, …)
  • Temporary power supply (overloads, line replacement, remote villages, …)
  • Maintenance works
  • Construction works


  • Spare energy units
  • High mobility
  • Low capital investment
  • Ready to use asset (connecting & energizing in approx. 12 hours)
  • Flexibility on operation
  • Compact designed solution
  • Tailor-made
Transformadores de Distribuição

Distribution Transformers

3phase hermetically sealed integrally filled distribution transformers in accordance with the requirements of IEC 60076 1-5 and Regulation (EU) No. 548/ 2014 (eco-design).

Oil immersed

  • Pole mounted
  • Ground mounted

Oil immersed

  • Cable connected
  • Unit substation

Special designs

  • Liquid immersed
  • Reactors

Dry Type Power Cast®

Ground mounted and special applications

Large distribution transformer – oil immersed

Substation transformer

Large distribution transformer – oil immersed

Mobile substation transformer