Cast Resin Transformers

Cast Resin Transformers


Carroll & Meynell have established close links with European manufacturers of Cast Resin Power Distribution Transformers.

Cast Resin Transformers offer a cost effective and convenient alternative to the more traditional Oil Immersed high voltage distribution transformers

The transformer itself consists of two types of winding. The high voltage winding (3KV up to 36KV) is vacuum cast into an insulating resin that completely seals it from the atmosphere. The low voltage winding (up to 690V) is wound with a pre-impregnated insulating paper that is heat treated to bond the coil together. These two windings are then placed concentrically on the legs of the transformers’ magnetic core.


Cast Resin / Oil Immersed comparison


No oil required
Low maintenance running costs
No requirement for oil spillage containment infrastructure


In-door applications only
Larger physical size
Initially larger purchase cost


Cast Resin Transformers are built in accordance with IEC 60076 they meet the following approval certifications

Climatic C1
Transformer suitable for storage and operation in ambient down to -25°C
Environmental E2
Suitable for highly polluted environment with substantial condensation
Fire F2
Self extinguishing that does not give out toxic substances or matte smoke


The standard electrical specification is for a High Voltage to Low Voltage delta to star step down transformer. However we can supply to a range of electrical specification options

  • Low Voltage to High Voltage step up
  • Full Rated Dual High Voltage windings e.g. 11KV / 20KV
  • Zig-Zag interconnected star Low voltage vector groupings
  • Dual seconday outputs for Delta / delta-star vector group transformers
  • K-Factor rating to allow for harmonic content loading

As standard the units are supplied with

  • Primary and Secondary Aluminium winding conductors.
    (Copper conductors are available on request.)
  • The HV windings are supplied with ±2.5%, ±5% taps
    The units are supplied with PT100 thermal monitoring sensors in each coil and a programmable TSX1 Thermocontroller *
  • Units are supplied with wheels

In addition to the transformer we can supply a range of accessories to suit the needs of the installation, these include

  • Enclosures
    • Rated IP21 or IP31
    • Bolt on access panels or Hinged lockable door panels
    • Floor mounting or transformer mounting
    • Choice of gland plate materials
    • Pre-Punched fitting holes for High voltage switches, Castell interlocks etc
  • HV Terminal Box
  • LV Terminal box
  • LV Bar Work
  • Cooling Fans to increase the transformer rating by up to 40%
  • TSX6c Fan Control unit
  • Option for PTCR sensors with TSX3 Relay monitoring unit *
  • Anti-vibration Pads
  • High Voltage Terminal Protection e.g. Elastimould fittings or Resin Pots

* Monitoring units are supplied loose for installation within the switchgear panel

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