Dry Type Transformers

Eltaş A.Ş manufactures cast resin dry type transformers upto 25 MVA and with maximum voltage rating of 36 kV. These transformers can be manufactured F or H temperature classes according to the customer requests and specifications.

We are proud of increasing the market share of domestic manufacturers in Turkey  with the start of manufacturing in 2005.

Our company has both “cast resin with fiber glass under vacuum technology” and “cast resin with quartz technology” which are used in manufacturing. Both of this two technology are referenced through German tech  and trouble free transformers are manufactured with the support of a Professional expert team.

The partial discharge parameter that specifies the transformer lifetime is <5 pC in our dry type transformers.

If dry type transformers compare with oil type transformers, minimising the fire risk in communal life places, not containing toxic chemicals inside that threats the human health in any kind of fire situation, being environmental friendly because of not changing oil and being exempt of oil leakages, taking up less place and maintenance free reasons are preferably.

Some of the areas that cast resin transformers are used;

  • Indoor and Outdoor Transformer Centers
  • Industrial and Oil Refineries
  • Metros
  • Oil Platforms
  • Power Plants
  • Schools
  • Hospitals
  • Airports
  • Shopping Malls
  • Wind Plants

Advantages of cast resin transformers;

  • Minimisation of cable investment costs with placing the transformer nearby the load centers
  • Lower sound level
  • Non-flammable and self extinguishing
  • Less area than oil immersed transformers for the same rating
  • Maintenance free
  • Moisture free coils
  • No need for drying for re-operation after deactivation for a long period
  • Coils can be changed on-site for any kind of reasons
  • Rated power can be increased %40 by cooling fans
  • Environmental friendly as it is not containing toxic chemicals inside
  • Distribution Transformers
  • Monophase Transformers
  • Earthing Transformers
  • Power Transformers
  • Transformers with On Load Tap Changer
  • Auto Transformers
  • Generator Transformers
  • Rectifier Transformers
  • Transformers with Air Force-Water Force Cooling (for Ship application)
  • Traction Transformers (for Subway application)
  • Transformers with Seismic Apparatus

1 - Coil Winding

2 - Core Production

3 - Vacuum

4 - Active Part Assembly

5 - Quality Control & Testing

Eco Design Transformers

With years of experience in the transformer sector, ELTAŞ supports the Eco Design Regulation. As a part of this, we design and manufacture our Cast Resin Dry Type Transformers according to Eco Design standards.

After the approval of the Kyoto protocol, the new environment-oriented and ambitious goal of the EU; to reduce greenhouse gas emissions by 20%.

The goals to be achieved in this scope include:

• 20% decrease in energy consumption;
• Raising power generation from renewable sources to 20% of the total; and
• 20% decrease in greenhouse gas emissions.

To achieve success towards this goal we implemented the concept of “Eco Design Transformer.” The two main goals of this concept are;

• Decrease in transformer losses and
• Significant improvement in transformer performance.

For detailed dimensions and losses; You can send an e-mail to [email protected] .



Our company serves for global market and manufactures according to the customer requests, current specifications and standards. If we sort some of these standards;

IEC 60076-11, NEMA ST 20, BS EN 50541-1, CSA C9-02, IEEE C57.12.01 , VDE 0532 / DIN 42523, TS 267 etc.

Low Voltage Windings

The foil winding technology is used for Low Voltage (LV) winding because of its technical advantages. LV winding is made of aluminium or copper foils according to the customer request. This technique reduces axial forces under short circuit and F or H (depends on customer request) class prepreg insulation materials are used in order to control radial short circuit forces. The coils are cured after winding to have dielectric strength against hardest industrial and atmospheres conditions. The LV windings are also manufactured as casted under vacuum depends on customer request.

High Voltage Windings

The high voltage windings (HV) are made of flat or round aluminium or copper wire with F or H Class insulation material. The HV windings are casted under vacuum to obtain voidless structure and cured slowly to have crackless coils. Due to Eltaş Cast Resin Transformers have very low Partial Discharge, they have very long life time.

Due to using additional cooling ducts in Eltaş Cast Resin Transformer’s HV windings technology, they have more affective cooling ability and strength advantage to HV pulses.


The core is made of highest quality, cold rolled grain oriented silicon steel. The cores are cutted and stacked with step-lap technology on fully automatic GEORG and TUBOLY machines. Lower no-load losses and sound levels are obtained with this method. The cores are protected against vibration and corrosion by resin coating and painting. The cores are grounded in accordence with required standards.


Two different technologies are used while performing casting operation.

Quartz - Filled Technology

  • Quartz is used as a filler material in resin system.

Windings are manufactured with double-layer paper insulation systems by using aluminium or copper conductor tapes in Quartz - Based Technology.

  • Fiberglass-reinforced resin technology (per customer request)

Fiberglass is used as a filler material.

Flat or round shaped aluminium/copper conductors can be used and with fiberglass reinforced resin, mechanical strength is unmatched.


Clamps are used for coil assembly in top and bottom side in Eltaş Cast Resin Transformers. This clamps hold the core and coils together. The coils are assembled with support blocks made of plastic with reinforced by fibre glass against short circuit and vibration. The wheels enable the transformer to be moved either lenght wise or side wise. All steel parts that are used in transformer assembly are painted with epoxy based paint against corrosion. The painting method is selected according to ambient atmospheric conditions of transformer’s site.

1. Temperature Control System (Standard equipment)

PT100 or PTC are placed in the LV winding to control the temperature rise in transformer windings. When necessary and if transformer has cooling fans this sensors switches on fans and switches off the transformer if the temperature rise continues and reaches the limits. Measurements can be transfered to computer with RS485, MODBUS, TCP/IP etc. communication protocols according to the customer request.

2. Forced Ventilation System (Optional)

Eltaş Cast Resin Transformer’s capacity can be increased %40 by adding fans which are selected with special design. The fans are switched on and off via sensors that assembled in the LV winding.

3. Anti-Vibration Pads (Optional)

Anti-vibration pads are used to decrease vibration on the transformer basement and to insulate this vibration in buildings, shopping malls etc. They are also used in lifting crane applications.

4. Enclosures (Optional)

Eltaş Cast Resin Transformers are manufactured IP00 (without enclosure) as standard. The enclosures against solid materials, water and dust are manufactured according to the customer request as per IEC 60529.

The Standart type enclosures are:

IP20 Indoor
IP23 Indoor and Outdoor
IP33 Indoor and Outdoor

The enclosures with higher protection degree can also be manufactured with special design forced air ventilated, water cooled, air conditioned etc.

5. Seismic Apparatus (Optional)

Eltaş Cast Resin Dry Type Transformers can be manufactured with seismic apparatus that avoids the movement of transformer and coils in earthquake according to the customer request. In these transformers special and high strengthened assistants are used for absorbing the vibration that occurs in earthquake. Our seismic withstand transformer has been passed the earthquake test in an European accredited laboratory with complying the radial and axial accelerations that are indicated in Tedaş specification. We passed the test in first time and transformer has been certified.

6. Other Accessories (Optional)

Surge arrester, current transformers, voltage indicator, enclosure heater, cable boxes that makes possible to enter the power cables from sides (only possible with enclosure), inter-lock system etc. are supplied according to the customer request.

7. On Load Tap Changers (Optional)

Energy grid voltages can be so variable in some areas. In these situations Transformers with on load tap changers are used to get a regular, specific fixed voltage. Eltaş manufactures transformer with on load tap changer upto 36 kV according to the customer request.