GEAFOL® cast-resin transformers – resistant to overvoltage by design

Distribution transformers are mainly used where electricity needs to be transformed from the medium voltage level down to low voltage, or to another incoming grid voltage level.

bySiemens Energy



Extremely safe, reliable in operation and environmentally compatible – Siemens Energy cast-resin transformers provide great customer benefits

Distribution transformers are mainly used where electricity needs to be transformed from the medium voltage level down to low voltage, or to another incoming grid voltage level. Unlike traditional fluid-immersed transformers, cast-resin transformers operate with high-voltage windings fully encapsulated in cast-resin insulation, instead of transformer oil or other liquid insulating materials, which makes a tank with insulating and cooling liquid unnecessary. Thanks to this apparently simple idea, the technology has been successful since its market launch in 1966. The percentage of cast-resin transformers, compared with traditional, oil-immersed distribution transformers, continues to grow worldwide – with good reason, as they offer characteristic benefits.

To avoid long low-voltage cable routes that increase transmission losses, transformers are usually installed near the electrical loads. This almost always means in areas frequented by people, which is why transformers must operate extremely safely and reliably. This applies as much to high-rise buildings, hospitals, data centres, metro stations, ships, and oil rigs as it does to paper mills, rolling mills, airports, and other infrastructure with high power requirements. In addition, transformers often operate near passers-by and residents, only separated from their immediate surroundings by the wall of a secondary unit substation or transfer substation or by a metal housing. That’s why safety is everyone’s top priority.

Dry-type cast-resin transformers provide a particular degree of safety in operation, especially due to their electrical strength and excellent fire behaviour – they are flame resistant and self-extinguishing. At the same time these transformers are eco-friendly and virtually completely recyclable, which makes them the perfect choice for areas where environmental protection is required. There are practically no restrictions on the place of installation of cast-resin transformers.

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