Low voltage transformer indoor

Low voltage (LV) transformers are absolutely necessary components used to adjust the voltage of a power system and provide galvanic separation of the end user appliances. Since there is no need to have characteristics of high dielectric strength as the ones offered by oil immersed or cast resin transformers, the typical LV model is built with dry type VPI (vacuum resin impregnation) technique, which grants reliability and simplicity in construction, while also ensuring a functional and durable insulation of the electrical equipment.
FDUEG has been designing, manufacturing and supplying LV transformers as series or custom products for the past 20 years. The experience gathered, naturally developed through a close relationship with its clients, allowed to produce hundreds of different models, tackling and solving any single issue appearing on each of them.
This problem solving attitude is kept as guideline to help new customers, as well as the established ones who have been choosing FDUEG for years, to face and close any issue that may arise concerning the transformers needed.

Low voltage isolation transformer indoor FDUEG
Low voltage transformer indoor FDUEG

Low voltage LV Dry-typetransformers VPI (vacuum pressure impregnation): efficient, compact, long-lasting and maintenance-free

Characteristics and applications

A low voltage transformer needs to be compact, of long-lasting service life and efficient in handling the power transmitted. It is also desirable to reduce as much as possible the maintenance it needs during its operations, to avoid the costs related to programmed repair stops. FDUEG carefully works in the optimization of all of these features, taking the due care in designing core, windings, insulation and stabilization frames of its devices.
The VPI technology allows to play with the parameters involved with some margins and acceptable tolerances, adapting the static machine to any of the working conditions it could face once it has reached its final destination: aggressive or particularly hot environments, marine areas, considerable altitude where the air is thin are treated carefully and systematically. All of the consequential effects on the transformers can be tackled during the design phase, so that the insulation remains effective for many years of full regime service.

Metallic cabinets, whose IP degree spans from 20 to 44, are available for sale; the electrical machine can, in turns, be cooled naturally or with forced air on the windings. For the most demanding requests in terms of heat disposal, FDUEG can set up a water cooling (WF) of the transformer, so that the ampere rating can be considerably enlarged: up to 6 kA in continuous regime can be handled through this technique.

FDUEG delivers low voltage transformers that can be of single-phase, three-phase or three-to-single phase construction. Typical applications include isolation transformers for standalone machines or for larger portions of an electrical system, for auxiliary power supply, sensor applications or power electronics.

Custom design



Galvanic separation transformers

This kind of application deserves a separate and detailed mention, as its importance and diffusion are remarkable within the market of low voltage transformers.
Also known as isolation transformers, galvanic separation transformers are used for the sole purpose of physically detaching two circuits (or portions of the system) from an electrical point of view, with their magnetic link acting as power flow limiter (together with the electrical short circuit impedance) in case of fault in the supply compartment. The voltage level (usually 400 V line to line) in not modified in coupling the two circuits.

Since the local distribution line voltage of a plant is almost always the same, galvanic separation transformers are normally defined as series products, and characterized by their power rating. Besides these common devices, FDUEG is able to provide this type of static machines to be specifically fitted for a power rating that is not contemplated in the usual listings, or for uncommon voltage levels. In addition to this possibility, in order to supply the appliances with their nominal parameters, the design can be set up so that the output voltage automatically compensates the inevitable drop caused by the transformer’s own impedance.

Beside the electric performance of the device, its losses are, in particular, kept under control: the choice of materials for both core and windings ensures a perfect performance from zero to full load, without disturbances due to saturation of the ferromagnetic part. These features all concur in improving the overall efficiency in power transfer and consumption, and are enhanced by a construction whose purpose is to avoid hot spots and to keep the temperature under control all around the device.

All characteristics and certifications concerning low voltage transformers do hold for the electrical insulation application: these include rating, cooling media, protection towards the environment and any other special characteristic.

Special constructions

The biggest share of the business of FDUEG involves special transformers with custom construction upon a client’s request. By supplying products to players in the most diverse sectors of application, the expertise concerning any model and their possible usage is deep and wide, covering any kind of weakness that may arise, along with its constructive solution.

In particular, among the many, the following fields of application stand out:

  • High current transformers for industrial and testing facilities: they allow to handle very low voltages (up to a few tens of volt maximum) and relevant currents, reaching some kA, required by special and particular loads. FDUEG is able to supply this kind of device also as triplet of single-phase transformers, exploiting as much as possible their modularity from the point of view of cooling and reliability.
    The output voltage of this kind of transformers is deeply affected by their short circuit impedance, due to the large current flowing. FDUEG takes care in designing their products so that the output matches the requests of the clients in full load, with the due tolerance for the optimum regulation.
  • Single-phase and three-phase transformers for medical environment: since they are applied in key facilities, the standards regulating transformers for medical environment are stricter regarding all safety aspects, from overheating to electrical insulation and stability. These requirements all aim at a device whose supply is granted in any possible circumstance.
    Their typical application consists in providing galvanic separation to specific areas of the electrical power system.
  • Transformers to be used in naval and marine environment: they can be able to sustain large power, and sport a definitely compact frame dictated by the particular need for a small footprint occupation. All optional characteristics and auxiliaries, usually related to a marine environment, can be applied to the transformers of FDUEG: these include high IP degree cabinets, coated or painted according to the standards in order to sustain atmospheres characterized by high salinity.
    FDUEG is equipped to host the witnessed FAT (Factory Acceptance Tests) procedures that are usually required for this kind of applications.


Technical data

High current transformers Up to
Up to
1,1 kV


Transformers for medical environment Up to
Up to 3,6 kV AN 
Naval transformers Up to
10 MVA
Up to
3,6 kV


Industrial electric power supply
Power Plants
Public, Medical and Commercial Buildings
Renewable Energies
fdueg applicazioni steelworks
Test Lab & Research Institutes
Offshore Plants
Data Centers


    Contact us
    +39 0321 824131

    Related products

    • Italian
    • English