Production is carried out in accordance with the technical specifications received from the client. All dimensions and relevant technical parameters must be indicated: internal diameter, outer diameter, coil height, winding patterns with the number of turns and tapping links, conductor-section values, insulation class etc …

On request, we can provide windings with sizes and dimensions which we determine ourselves and are calculated on the basis of the technical specifications submitted by the client.

Production is carried out in a manner compliant with provisions relating to “Quality Systems” in the ISO 9001 (2000) regulations. In accordance with these rules, the entire manufacturing process is checked, from the moment raw materials are received (e.g. conductors, resins etc …) to the final ‘finished products’ stage. Particular attention is paid to the winding, assembly and resin casting phases.

Partial discharge tests

We have carried out partial-discharge measurements on several of our coils in accordance with the IEC 726 standards, detecting values ​​constantly below the value of 10 pico-coulomb (pC). We guarantee this level of partial discharge, as long as the assembly of the transformers respects the necessary dimensional and procedural parameters, and in particular the distance between the HV and LV coils and distances to ground.

Impulse test

We have performed impulse tests on numerous transformers assembled with our coils, in accordance with the IEC 5.1.76 standards and with a positive outcome.
The observations concerning partial discharge tests remain valid also for this type of test and, that is, the transformers must be assembled in accordance with the dimensional parameters.

Thermal-shock test according to IEC 726

This test consists in lowering the temperature of the coil to -25 ° C over 8 hours, and maintaining this temperature for a further 12 hours.
The coil must then be powered with a current at twice the rated value, rising to an over-temperature of 110 ° C, without causing cracks.

The windings are provided with an identification card and the related test results sheet. If requested by the client, the following tests will be carried out:

  • ratio measurement
  • measurement of resistances
  • insulation test (to earth and secondary)
  • over-voltage test
  • partial-discharge test


On request, we can provide clients with pressure pads, which are used to maintain low-voltage windings centered and levelled with respect to resin coils.
The pressure pads are produced with highly resistant plastic material.
As is known, rubber plugs are used to compensate for slight differences in the sizes of HV and LV coils and, above all, to offset dimensional variations of the coils caused by working temperatures.


At the client’s request, we also provide electronic control units for the detection of the temperatures of the three LV windings and the core.
Besides monitoring the temperature of the 4 sensors, these units provide relay contacts for an alarm signal that can be used for the release of the transformer.

The client's logo can be set in the resin to a depth of 2-3 mm in the terminal section at the front of the coil. The location of the logo will be agreed with the client.


Prices are determined in budgetary proposals in accordance with the client's specifications.


The coils are guaranteed for 24 months from the date of delivery.
The coils are guaranteed for 24 months from the date of delivery.