The technology of GEAFOL dry-type transformers

The GEAFOL principle has succeeded in producing distribution transformers with excellent electrical, mechanical and thermal characteristics, which have also proven to be particularly compatible with the environment.
Compliance statement

Siemens Energy complies with the laws and regulations affecting distribution transformers

Siemens Energy is closely monitoring the development of transformer regulations worldwide e.g. European Eco Design Directive and US DOE rules. Siemens Energy adheres to the rules and regulations communicated e.g. in US and Europe and complies with all relevant requirements for every transformer product delivered. As a trustful and responsible partner Siemens Energy understands the importance of these regulations and will continue to monitor potential future requirements. We will continue to adapt and comply with all relevant regulatory changes.

Find out why the GEAFOL is setting new standards

Exceeding highest safety standards

GEAFOL dry-type transformers conform with the fire behavior, environmental and climate classes defined in standard IEC 60076-11 as follows:

  • E2 Environmental class (E3 on request)
  • F1 Fire behaviour class (highest defined class)
  • C2 Climate category     (C3, C4, C5 on request)

Since July 1, 2015, transformers that are installed within the European Economic Area (EEA) must meet the ecodesign requirements of the new directive, provided that they fall within the scope of the directive. Because the directive is a measure to implement Ecodesign Directive 209/125/EC, the CE mark is used as evidence of compliance. GEAFOL Neo transformers are designed accordingly and are particularly low-loss and economical. The transformers fulfill standard DIN EN 50588-1. In addition, the GEAFOL Neo can already be configured in accordance with stage two of the Ecodesign Directive, which sets even stricter minimum standards for energy efficiency and must be implemented by July 1, 2021.

EU requirements for transformers

We produce the GEAFOL in accordance with VDE 0532-76-11, IEC 60076-11, DIN EN 60076-11, DIN EN 50541-1 and EN 50588-1 (ecodesign). GEAFOL dry-type transformers also can be designed to meet special national specifications, or customers’ wishes. The high quality standard of the GEAFOL transformers was confirmed from the result of several tests: For example, one and the same GEAFOL transformer has passed all defined routine, type, and special tests, as well as additional tests, with flying colors. The comprehensive safety certification enables the use in almost every environment and under extremely harsh conditions such as:

  • Ambient temperatures of ± 60 °C
  • Aggressive, salt-laden atmospheres
  • Great mechanical stress e.g. on ships, cranes or nacelles of wind power plants

Declaration of conformity

Brochure "Behavior of GEAFOL transformers in fire"

Brochure "GEAFOL certificates"

Maintenance-free & eco-friendly

GEAFOL dry-type transformers are insulated with an epoxy resin and quartz powder mixture – an eco-friendly material that makes the winding

  • almost maintenance-free
  • moisture-resistant
  • tropicalized
  • flame-retardant
  • self-extinguishing

No toxic gases are produced, not even under the effects of arcing. And the specially developed spacers of the coil support system ensure isolation of vibrations from the iron core, which means very low noise levels.

Electrically safe

The coils of the high-voltage windings are made of aluminum foil.

Why foil windings?

  • They combine simple winding techniques with high electrical safety.
  • Insulation is subjected to less electrical stress than in other types of windings.
  • The result: high power frequency and impulse voltage withstand capability.

Why aluminum?

  • Thermal expansion coefficients of aluminum and cast resin are similar.
  • The result: thermal stresses due to load changes are kept to a minimum.

On request, we also offer dry-type transformers with copper windings, namend CARECO.

No gas inclusions

The high voltage windings are potted with epoxy resin under vacuum at a high temperature:

  • Undesirable gas inclusions are prevented.
  • Freedom from partial discharges (up to twice the rated voltage) is provided.

The low-voltage strip winding is also made of aluminum. The width of the aluminum strip is equal to the length of the coil:

  • Axial short-circuit forces in the transformer are reduced.

The conductor strip and insulation material are bonded together by heating:

  • A compact unit with sufficient strength to reliably withstand radial forces is created.


GEAFOL dry-type transformers still have benefits even at the end of their life cycle: without any danger to the environment, 94 percent of the material can be recycled.

Find the right GEAFOL / CARECO dry-type transformer

Accessories and individual solutions for our transformers

For our GEAFOL dry-type transformers, we offer accessories and tailored solutions that suit your individual needs. Here is a selection of additional equipment available upon request:

New housing design

Proven technology in a new design

Innovation is something you can also see, at least when it comes to the new, award-winning GEAFOL housing whose stylistic idiom is based on the new transformer family design. Besides these purely visual aspects, the housing offers our customers other benefits as well.

Higher mechanical stability

Because the transformer and housing are delivered on a common base frame as a permanently mounted unit, they offer an extremely stable, robust overall configuration. This is further supported by the mechanically fixed installation of the transformer and the use of phases at the housing corners. Crossbraces can also be used at the transformer on request.

Greater flexibility and safety

The housing roof can be opened from the inside to permit hoisting by crane. The bolts connecting the housing and transformer are accommodated inside the housing for a higher degree of personnel safety. And thanks to the fully modular construction, a subsequent upgrade to a higher protection class (IP class) is possible at any time. Versions for indoor and outdoor installation in multiple protection classes as well as various installation options such as, for example, “infrared window,” are available. Further information upon request.

Explore the GEAFOL

Success stories and case studies

Learn more about latest applications of Siemens’ GEAFOL transformers


Contact and ongoing service

Ongoing service

Our responsibility does not end with the delivery – beside the application of our service engineers on-site we offer individual trainings for your employees. For more information we are gladly at your disposal at any time.

Contact us and get your GEAFOL transformer

Do you need a tailored transformer solution to meet your unique business challenges? Tell us your requirements and we will find the right GEAFOL dry-type transformer

We offer customized solutions for your needs

Contact us


Make use of our services

For your convenience, we have assembled relevant downloads as well as details of support contacts below.
Fields of operation

Discover the many fields of operation

Since 1965, over 100,000 GEAFOL Cast-Resin Transformers have proven themselves in power distribution or converter operation around the globe. Whether in a wind park in Tasmania, a paper production factory in South Africa, or the Transrapid line between Shanghai and the Pudong, our dry-type transformers ensure reliable power supply anywhere, any time.

GEAFOL contributes to eco-friendly power on the high seas

-12 %

approximate savings on CO2 emissions

0 %

approximate overall machinery efficiency

Siemens has been awarded to equip 20 Mærsk Triple E ships – the world’s largest and most modern container ships – with eco-friendly power generation systems. 40 GEAFOL Cast-Resin Transformers, each with a capacity of 4,400 kVA, will be part of the waste heat recovery system on board.   *The first Triple class ship: the Mærsk Mc-Kinney Møller in Bremerhaven, Germany

Reliable energy for Germany’s largest cloud

0 MW

maximum power consumption

0 km2

Despite its huge IT area, the data center ranks among the most modern and energy-efficient in its class

Siemens has installed power distribution systems in the biggest data center in Germany, operated by Deutsche Telekom. The systems are specifically designed to meet the data center’s high demands: a power interruption of more than 10 milliseconds can lead to massive disturbances. 18 GEAFOL Transformers, each with a capacity of 2,500 kVA, ensure a reliable power supply.

Top performance under extreme circumstances

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drilling depth below the sea floor

  Siemens supplied two complete power packages for Statoil‘s new semi-submersible drilling units on the Norwegian Continental Shelf. 2,400 kVA GEAFOL converter transformers keep the systems running and guarantee low maintenance and service – even under extreme harsh ambient conditions.

Fairs and events

Stay up do date in the matter of GEAFOL

Learn more about the GEAFOL at one of the following trade fairs: