GEAFOL Cast-Resin Transformers

Our environmentally friendly GEAFOL dry-type transformers are setting new standards

Wherever distribution transformers have to assure the utmost safety in areas frequented by people, GEAFOL® cast-resin transformers are the ideal solution. With GEAFOL, the limitations of liquid-filled transformers are avoided, but the proven electrical, mechanical and especially thermal characteristics are retained.

GEAFOL transformers from Siemens Energy exceed highest safety standards and comply to all relevant laws and regulations.

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

  • E3 Environmental class (higher classes on request)
  • F1 Fire behaviour class (highest defined class)
  • C3 Climate category (higher classes on request)

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.

We produce the GEAFOL in accordance with VDE 0532-76-11/IEC 60076-11/ DIN EN 60076-11 and the Ecodesign Directive from the European Commission. Other standards, such as GOST, SABS, or CSA/ANSI/ IEEE, can also be taken into account on request. 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

EU requirements for transformers

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

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.

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.

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 transformers are insulated with an epoxy resin/ quartz powder mixture instead of oil - a very environmentally friendly alternative. Besides, GEAFOL dry-type transformer are completely recyclable​.

GEAFOL transformers from Siemens Energy are produced as Sensformers per default. This means they are equipped with sonsors, that are transmitting operational status data to a secure storage and analytics tool. Operators can optimze operations based on customized data analytics.

Sensproducts Website

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:

PTC thermistor temperature sensors, PT 100 resistance temperature detectors or a capillary tube thermometer can be employed for temperature supervision of GEAFOL transformers.

Radial-flow fans with temperature-dependent control can be installed to provide capacity reserves and to cover peak load periods. In this way, the transformer output can be raised by up to 50 percent.

To provide protection for the transformers against environmental influences and to prevent people from coming into contact with the transformer, we offer standard housings, and optionally, modified housing designs.

To simplify installation and connection, the transformer is optionally available with connection on the HV or LV side, top, or bottom. Plug connections are available as well.

Find the right GEAFOL / CARECO dry-type transformer

Making a difference

Siemens Energy GEAFOL cast-resin transformers are built for operations and environments all over the world. They not only meet highest customer requirements, but comply with both national and international standards.

Make use of our services

For your convenience, we have gathered relevant downloads in one spot. If your question is still unanswered, please feel free to contact our Energy Support Team.

Brochure downloads

GEAFOL Neo: Convincing technology creates compact performance
PDF (5 MB)
GEAFOL for wind applications: Environmentally friendly, robust, and highly efficient
PDF (387 KB)
Operational manual: GEAFOL and CARECO dry-type transformers
PDF (1 MB)
Cast-resin transformers / China
PDF (4 MB)
Operational manual / China
PDF (4 MB)

Contact the Customer Support Center


Humboldtstr. 64


Contact form

For general information, please visit

Digital showroom

Transformer services

Transformer laboratory