T:+44 208 681 1223 E:enquiries@otds.co.uk Tweeter Facebook

Cast Resin Transformers | Dry Type Transformers

Cast Resin Transformers | Dry Type Transformers

OTDS manufactures 3 phase cast resin transformers up to 15mva and dry type up to 150kva. Our voltage range is up to 36kv for cast resin units and 3kV on dry type transformers.

Our three-phase transformers of cast resin type, class F insulation system with natural (AN) cooling are designed for indoor installation. If required, forced cooling (AF) to increase the rated power up to 40% and enclosures of up to IP44 are available.

Our cast resin transformers are manufactured in accordance to IEC60076-11 and a quality system in conformity of ISO 9001.

See our attached documentation for our general catalogue, drawings and gallery for some high quality images of our cast resin transformers and dry type transformers.


We also manufacture a wide range of distribution and oil filled transformers.

Please send us your requirements enquiries@otds.co.uk


The cast resin transformers  are regarded as a convenient and largely cost-effective alternative to traditional oil filled transformers. The insulating resin seals the unit from the atmosphere, ensuring that the unit can be installed in a polluted environment close to the load. This means that, though dry type transformers are not suitable for outdoor use and are often larger in size than their oil filled counterparts, they are perfect for use in areas that experience high fluctuations in temperature or are exposured to condensation and dust.

Dry Type Transformers

Dry type transformers offer plenty of benefits when used for indoor applications or in areas with extreme climatic conditions. A dry type transformer will cool by air ventilation rather than the use of oil, eradicating the fire risk posed by oil filled units. As there is no need to replace the oil regularly, these units require minimal contamination checks and very little maintenance over time.


  • Our cast resin transformers are self-extinguishing and are guaranteed to protect against fire hazards
  • All of our cast resin and dry type units are fully insensitive to extreme or harsh environments and are resistant to pollution or condensation
  • Easy to install and maintain


  • Infrastructural projects
  • Public and commerical buildings
  • Switchgear substations
  • Small industries (including the textile and automotive sectors)

Standard Manufacture And Features;

  • Primary Voltage Up To 24 Kv;
  • Secondary Voltage Up To 0,690 Kv
  • Insulation Class Up To 24 Kv
  • Connection: Delta/Star With Neutral, From 100 Kva To 3150 Kva (Other Upon Request)
  • Vector Group: Dyn11 Or Dyn5 (Other Upon Request)
  • Frequency: 50hz
  • Core Made With Insulated Grain-Oriented Magnetic Steel Foil
  • Encapsulated Alluminium Primary Winding
  • Impregnated Alluminium Secondary Winding
  • Primary Voltage Tap Changers
  • Lv Terminal Plates
  • Bi-Directional Rollers
  • Lifting Lugs
  • Earthing Terminal
  • N° 3 Pt100 Temperature Sensors Connected In A Box
  • Electronic Temperature Monitoring Unit
  • Data Plate
  • Protection Grade Ip 00


Special Options;


  • Primary Voltage Up To Kv36
  • Dual Primary Voltage
  • Dual Secondary Voltage
  • Multiple Secondary Voltage (E.G. For Use In Pv Systems)
  • Copper Primary And Secondary Windings
  • Non-Standard Losses And Voltages (Upon Request)
  • Non-Standard Connections And Vector Groups (Upon Request)
  • 60 Hz Frequency
  • Electrostatic Shield Between Primary And Secondary Windings
  • Mv Outer Cone Elastimold Type Separable Connectors
  • Air Forced Fans
  • Forced Air Cooling Electronic Monitoring Unit
  • Digital Output Rs485 Module Or Analog Output 4-20ma Module
  • Infrared Temperature Monitoring System (Recommended For Mv/Mv Transformers)
  • Ip 31 Protection Grade Panel Enclosure, Mounted On The Transformer – Ral 9002 Paint
  • Tropicalisation Up To +55°C (For Installation In Countries Such As United Arab Emirates)
  • Customisation For Use In Arctic Weather Conditions With Temperatures Down To -60° C (E.G. Russia)
  • Surge Protection Kit (Strongly Recommended In Case Of Connection To Overhead Power Lines Or Lines Without Surge Protection)
  • Other Features Upon Request.