The construction of this type of medium voltage transformer requires the IRAM 2250 and IEC 76 standards.

They can be constructed according to 3 variables:

a. With expansion tank.
b. No expansion tank. Airtight with expansion chamber.
c. No expansion tank. Hermetic integral filling.

The latter, as the name implies, are completely filled with oil, there is never an exchange of air with the atmosphere, thus preventing the entry of moisture and the contact of the fluid with the oxygen of the air.

Reducing oxidation degradation and increasing oil and transformer life with minimal maintenance.

Its finned bowl absorbs the differences in volume produced by changes in temperature.

It is compact in appearance and small in size.

They are hermetic impregnated in mineral oil and can be submerged under the water.

Its application is for those places with ease of flooding as much rain as for ascent of the sheets.

For this, its surface paint scheme has an epoxy base with high zinc content and bituminous epoxy termination.

Due to its usefulness and design, it has, besides normal ones, special accessories such as:

· Plug-in MT connectors with pole-type operation - elastimold type.
· BT - insulated copper rods with epoxy.
· Externally operable limiting sheaths and fuses.
· Pressure gauge for internal pressure control.
· Pneumatic valve for the evacuation and injection of nitrogen.
· Safety valve to release excessive nitrogen overpressure.

The production line of FOHAMA ELECTROMECANICA is prepared for the manufacture of electric transformers up to 30MVA and tensions of 132kV.

Each transformer is designed and manufactured according to customer requirements and specifications, complying with national and international standards and standards IRAM, IEC, ANSI, IEEE.

Design of windings with insulation systems conventions on kraft paper and hybrid systems in Nomex - kraft paper.

Use of inhibited mineral oil, not inhibited and esters as insulating liquid. Synthetic and natural esters are requested by customers, for having great advantages like high temperature of inflammation and to be biodegradable.

For the preservation of the insulating liquid, a high quality flexible membrane system can be included to avoid contact of the liquid with the air, preventing oxidation and humidity.

Switches without voltage, under load or both can be installed. On-load switches with vacuum or oil switching technology are available. On request a filter unit can be installed in combination with the switch.

To prevent overvoltages and protect the transformer, surge arresters are coordinated with the system.

Designs with different cooling systems ONAN - ONAN / ONAF - ODAF - ODWF according to requirements, controlled by electronic or electromechanical thermal images. Equipment for direct temperature measurement of core and windings via fiber optic are available.