Resin Transformer

Product ID: Resin Transformer

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The cast resin transformer is a special type of dry transformer (CEI 14-8). The dry transformer are the transformers without active part immersed in a liquid insulation. When a transformer has one or more windings casted is commonly know as Cast Resin Transformer.
The cast resin transformers has obtained a huge evolution in terms of building techniques and used materials (i.e. epoxy resin), and for this reasons they are founding now a very considerable feedback from the market inquiries, also thanks to them to nothing maintenance despite of oil transformers and also characteristics and reduce at minimum fire risk and ambient impact.
The medium voltage active parts of a cast resin transformer are casted with epoxy resin and warmed under vacuum to prevent the origin of micro air bubbles and gasses inside of insulating materials.
These casting process gives give to the winding a perfectly cylindrical shape with a smooth surface with less deposition of dust and pollutants and / or corrosive. This process allows to the winding to be also mechanically robust and waterproof.
The casted windings are spitted in more winding’s part, each of this part has a single wire for each layer, the reason of this projection choice is that this type of construction reduce to minimum the voltage gradient in the interior of the winding and so also the probability of initiation of partial discharge. The winding is usually done in aluminum. Aluminum is used because its coefficient of thermal expansion is very similar of resin coefficient, so the changing of temperature of the transformer in this case can generate only very limited mechanical forces.
The low voltage winding are manufactured with a single strip of aluminum identical in height to the medium voltage winding.
This particular construction, with low voltage winding in a single aluminum foil and medium voltage winding in more strip of aluminum reduce the axial forces in case of short circuit.
The insulation between the wire is ensured with a foil of pre-preg epoxy resin material, this one with a thermal treatment and also in the normal use goes to mate making solid the winding and resistant but at the same time free to move with a certain elasticity.
The windings manufactured with these methods are very resistant to condensation and pollution.

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Cast resin transformer