Support rod of composite material for power transformer coils

At large size transformers, there are slots between the iron core and the coil around it. This is partly because the boundary of the iron core is gradual and partly because at such large size, it is not possible to exactly match the dimensions of the iron core and that of the inner ring of the coil. Therefore, wooden rods are generally placed in the grades of the iron core, which are ground to the appropriate size. This operation on each transformer requires several hundreds of labour hours. However, the matching will not be perfect even so. Due to the matching defects, shortcuts may spoil the transformers.

The Transpolym technology by the development of Kompozitor applies a composite structure to replace the wooden rods as per the following method:

Textile tubes (Textube) of 15-45 mm diameter and tenth of mm wall thickness are placed in the grades of the iron core. Following that, the transformer coil is placed on the iron core within a few minutes. The ends of Textube tubes standing out of the transformer widen out. The resin mixed with the catalyst is filled in the Textube tubes. The pressure by the composite presses the Textube tube against the surface of the coil and it that state it gets hardened “irreversibly”. This makes a perfect match with no human labour needed at all.



Transpolym material characteristics:

Density: 2 kg/dm3
Bearing strength (perpendicular): 115 MPa -15°C
110 MPa 20°C
80 MPa 130°C
Flammability: Non-flammable DIN 4102


Textube dimensions, parameters:

Internal diameter: 15-45 mm
Length: 1-5 m
Wall thickness: 0,15 mm
Tensile strength (chain): 60 MPa
Tensile strength (weft): 140 MPa
Operational temperature: -50-150 °C

Advantages of the use of Transpolym:

  • Significant labour hour saving (80%).
  • Outstanding matching accuracy.
  • High mechanical hardness.
  • Protects the coil from breaking.
  • Operational temperature -50-130°C.


The development of the Transpolym product began in 1996, since when is has continuously been installed in the 200 to 320 MVA transformers produced by CG Electric Systems Hungary Zrt. (formerly Ganz Transelektro Zrt.). This is also the technology process the Indian Crompton Greaves Limited transformer producer applies.