Our know-how


Transfos MARY réalise sur demande la conception, l’étude et la production de transformateurs et de bobines spéciales répondant aux cahiers des charges les plus exigeants en termes d’économies d’énergie, du durabilité dans des environnements extrêmes ou de spécificités d’applications.




With more than 70 years of expertise and know-how, Transfos MARY offers single-phase, three-phase, standard and specific transformers with characteristics and performance perfectly adapted to the requirements of its customers in industry and the tertiary sector.

  • Single-phase and three-phase dry electrical transformers
  • Standard and specific technical characteristics
  • Special windings
  • Moulded transformers (series only)
  • TIG welding (aluminium winding)
  • Vacuum impregnation (better protection option)
  • ISO 9001 certified


Production options

The regulation tabs allow you to select different operating voltages.
  • Additional insulation: in case of failure of the main insulation, discharge of the defect to the ground without communication with the secondary.
  • Static interference attenuation: In the case of a computer power supply, it releases part of the static interference of the network to the ground.
Additional safety devices, the probes allow to check the operating temperatures of the transformer. Thermostatic probes, PT100 and PTC are available.
On request, we carry out a special treatment with a layer of “anti-flash” varnish on the entire device and improve the resistance to moisture, fungi, mold and conductive dust.

The impregnation under pressure and vacuum allows a complete and deep application of the protective varnish for the transformer. This process is more efficient than simple soaking but remains much longer and more expensive. This process allows a better mechanical hold of the varnish and further improves the durability of the transformer.

The anti-vibration pads absorb any vibrations produced by the magnetic circuit.

The optional bearing rollers allow the transformer to be moved over a very short distance (1 to 2m) to facilitate installation and maintenance.


Option available for transformers in enclosed versions, primary and secondary protection circuit breakers assembled and wired in factory.


Standard box up to 2500 VA.Protects against foreign solid bodies with a diameter of 1 mm or more. Protects against vertical drops of water.


Standard box from 3150 VA.Protects against foreign solid bodies with a diameter of 12.5 mm or more. Protects against vertical drops of water.IP23 and IP31 available on request.


Protected against dust (dust penetration is not completely avoided, but dust does not penetrate in sufficient quantities to interfere with the operation of the transformer or safety). Protection against water splashes.


Dust-proof (no dust penetration). Protection against spray water.


You are looking for a data sheet for a single-phase or three-phase low voltage dry transformer or additional information on our other standard and specific products, see our product search module.

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Having climbed all levels of production, from assembly to winding, I produce, with my team, high-quality transformers that meet the demands of our customers around the world.

Ludovic – Production manager

22 years at Transfos MARY

“Participating in the transformation of the world”

It is exciting to design transformers to meet the different needs of our customers.

Patrick – Design office manager

30 years at Transfos MARY

“On request transformers”

With our high-performance test benches, we guarantee the quality and reliability of our devices.

Pascal – Tests operator

20 years at Transfos MARY

“Being at the heart of the security of your facilities, all our devices are controlled.”

Making coils with yarns as fine as hair (5 hundredths), welding them requires rigour, meticulousness and important know-how.

Eric – Precision winding

13 years at Transfos Mary


Always listening to our customers to advise them and define the best solutions together.

Valérie – Office-based sales manager

17 years at Transfos Mary

“Listening is the key”