Cast Resin Transformers Features

Cast Resin Internal Structure

Cast Resin Transformer Cross Section

HV Winding

• LV terminals for connection cables
• Core uses ‘step-lap’ cutting technology of grain-oriented magnetic steel sheets to reduce energy loses, vibration and reduce noise.
• HV windings. Sequences of  aluminium or copper conductors are insulated with polyester film, cast under vacuum in epoxy resin. This ensures partial discharge at less than 10%. Dielectric materials are Class F.
• LV windings use aluminium or copper foil conductors with flexible pre-impregnated class F/H insulating materials oven cured for polymerisation. This also substantially reduces axial stress of short circuits.
• Self-extinguishing Class F1 epoxy resin. Also protects the transformer from hudity and corrosion.
• Zinc-coated frame
• Primary windings are fitted with a 5 position tap changer +/-2 x 2.5%. (Other values available on request.)
• Standard vector group is Dyn11. (Other vector groups are available on request.)
• Transformers are normally designed for 40 °C ambient temperature, but can be designed for locations with ambient temperatures of up to 55 °C.
• Overload protection. Each transformer is supplied with 3 x PT100 thermo resistors, inside each LV winding, which can be connected to a temperature control unit (optional)
• Standards. Meets conformity class E2C2F1 Environmental, Climatic, Fire Behaviour. Each transformer undergoes routine testing (IEC 60076-11) for the following:
  • Winding resistance
  • Voltage ratio
  • Short circuit impedance
  • Load losses
  • No-load loss and current
  • Applied voltage test
  • Induced voltage test
  • Partial discharge