Cast Resin Dry Type Transformer

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Cast Resin Dry Type Transformer (CRT Type)

Balaji Power Automation is well known for three phase cast resin dry type transformer manufacturer, supplier and exporter from India.

Our cast resin dry type transformers comply with national along with international standards such as IS 11171, IEC 60076-11, BS and CE. Also we use enclosure of IP55 Degree of Protection rating.

We manufacture cast resin dry type transformers up to 5 MVA and 33 kV Class. These transformers are air cooled.

Technical Specification:

RatingUpto 5 Mva
Duty TypeOutdoor/Indoor, Ground Mounted Type& Pole Mounted Type
Voltage ClassUpto 33Kv
No Of Phases3 phase
Frequency50/60 Hz
Vector GroupDyn1 or Dyn5 or Drn11 or any specific
Class Of InsulationF , H Or C class as required
Temperature Rise90.C to 115.C above ambient temperature of 50.C by resistance method or as per customer’s requirement
Tap ChangerOff Circuit or On Load
Tapping Range+-2.5% X 2 for OCTC or +-2.5% X 2 & -2.5% X6 for OLTC as per customer requirement
Winding MaterialAluminum Or Copper with multi paper NOMEX covering
Applicable StandardsIS 11171,IEC 60726
EnclosurePaintingPowder Coated with RAL 7032 Shade or as per customer requirement

Manufacturing Process

Manufacturing Process Core:

Three limb core construction is used. Core sheets conforming to drawings are made from Cold Rolled Grain Oriented (CRGO) Silicon Steel sheets. Individual sheets come duly coated with inorganic insulation. Circular Core cross section is used which is obtained by assembling number of steps of different widths. Number of steps and step widths are optimized to gain maximum advantage. Mitred joints are used between the limb plates & yoke plates. Fibre -glass tape banding hold the core tight and reduce the noise level. Treatment given to the completed core, protects it from atmospheric corrosion.


Both the H.V. and L.V. windings are made from copper conductors. Round wire, rectangular strip or foil is used depending on current to be carried. Layer type or cross over type winding is used depending on current / voltage to be handled. Windings are cast under vacuum.

On the H.V. side, inserts are provided to receive tap changing links. Inter connections between H.V. phases are obtained by links made out of copper tubes with their ends formed into lugs. These links are insulated by means of heat shrinkable tubes.


Protection against Overload/high winding temperature can be provided by Thermistors. ALARM and TRIP are provided, when required, by means of Thermistor or RTD sensors can be provided with 2 set points.

Advantage of Cast Resin Transformers:

  • No Fire Hazard.
  • Near Load Center or even near to load.
  • Low as transformer is near to load. Also cable drop is reduced.
  • Negligible smoke generation.
  • Suitable for indoor use as no fire risk.
  • Can be fitted outdoor in IP 45 enclosure.
  • Suitable for as low as -25° C ambient temperature.

Application of Cast Resin Dry Type Transformer:

These transformers are utilized in small and medium voltage distribution network for hotels, feeding basements or stilts of high-rise buildings, air ports, stadium, shopping malls, chemical, refinery plants and industries located in coastal regions.

Balaji Power Automation is amongst the leading names of Cast Resin Dry Type Transformer in India.

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