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GEAFOL Cast-Resin Transformers

Environmentally friendly dry-type transformers

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    Low-voltage terminals

    Delta connection tubes with high-voltage terminals

    Insulation with a mixture of epoxy resin and quartz powder

    Coil support system to insulate core and windings from mechanical vibrations

    High-voltage tapping links ±2 x 2.5 % permitting adjustment to system conditions

    Clamping frame and truck for lengthwise or sidewise travel

    Three-limb core made of grain-oriented, low-loss electro laminations

    Low-voltage winding made of aluminum strip

    High-voltage winding made of vacuum-potted single foil-type aluminum coils

    Output range from 50kVA up to 0 MVA

    Operating voltages up to 52 kV

    Customized solutions for
    individual requirements

    You need specific information on GEAFOL transformers?

    Order info package

    GEAFOL is celebrating its anniversary!

    Based on trials of cast resin-insulated dry-type transformers in the 1950s, the GEAFOL cast-resin transformer, with its pioneering winding concept, was officially launched in 1965. Since 1966, GEAFOL has been the perfect solution wherever distribution transformers have to guarantee maximum safety in the direct proximity of people. Other outstanding features of the GEAFOL transformers are their high dependability, long life and low environmental impact.


    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.


    Brochure "GEAFOL cast-resin transformers"

    Brochure "Planning Guidelines"

    Fairs (extract)

    Find out why the GEAFOL is setting new standards

    Exceeding highest safety standards

    GEAFOL dry-type transformers satisfy the requirements of the highest-defined classes, as proven by comprehensive testing:


    • E2 Environmental class
    • F1 Fire resistance class
    • C2 Climate category

    GEAFOL Cast-Resin Transformers can be designed to fulfill the new EU requirements for transformers, which will apply throughout Europe starting in July 2015.


    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


    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 offer dry-type transformers with copper windings.

    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 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:

    Explore the GEAFOL

    Installation and operation

    The following operating instructions guide you through installation, connection, temperature monitoring, commissioning as well as cleaning and inspection of your GEAFOL:


    The Siemens GEAFOL App

    With our GEAFOL App for Apple and Android devices, you can watch the operating instructions on- and offline on your tablet or smartphone:

    Ongoing service

    Our responsibility does not end upon delivery. On request, we provide comprehensive assistance for GEAFOL dry-type transformers:

        - Programming control systems

        - Taking measurements on-site


    In addition, we offer individual trainings for your employees and professional training events. For more information, feel free to contact us.

    Do you have any questions regarding our services?
    Contact our support

    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.


    Brochure "Transforming know-how into success”





    GEAFOL contributes to eco-friendly power on the high seas

    -12 %

    approximate savings on CO2 emissions

    0 %

    approximate overall machinery efficiency

    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

    Top performance under extreme circumstances

    0 m

    drilling depth below the sea floor



    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