In this type of transformer, the magnetic circuit and the windings are immersed in an insulating liquid such as mineral, silicone, ester or vegetable oil. The choice of oil is linked to the type of installation and the specific requirement of the Customer and where it is necessary to ensure special guarantees in terms of environmental impact and safety in the event of a fire.
GBE SpA manufactures oil transformers for all applications, in particular transformers for distribution and special MV/LV, MV/MV, LV/LV, HV/MV, HV/LV and HV/HV transformers with power from 50kVA up to 50 MVA, up to voltages of 145 kV (BIL 650 kV), with vacuum or load tap changer.
The primary and secondary windings of the oil transformers are built of aluminium and/or copper with conductor insulation made of pure cellulose paper or, for small diameter wires, of double enamel.
These windings have an oval or circular section and concentric type, coaxial to the columns of the core.
The transformers can be hermetically sealed, with an air/nitrogen cushion or with conservator.
Transformers up to 6,300 kVA can be with finned tanks, but it is recommended for power above 3,150 to provide the conservator. For bigger powers, cold rolled stamped steel, galvanized radiators are provided on request.
GBE steelworks can create not only the profiles and bases used in transformers, but also standard finned tanks, standard radiators and special tanks for special requirements on the positioning of the terminal or for specific dimensions. The transformer may be provided with a protective box on the LV side and/or on the MV side or on both sides. Special cable box can also be provided with above or below cable entry, complete with connection bars, if necessary. Upon request, transformer can be supplied complete with a circuit breaker/switch on either the MV side or the LV side.
The surfaces of the domestic manufactured tank are treated with suitable preparation processes, phosphating, washing and coated with water-based coatings using the flow coating RAL 7031 method (approved by ENEL) or RAL 7033 which ensures excellent resistance of the coating in all environments. The guaranteed minimum thickness depends on the coating cycle requested, which can provide multiple layers with different coatings . The standard coating cycle is the C3, but for industrial or coastal areas with high humidity and corrosive atmosphere, GBE guarantees C4, C5i and C5M cycles.