Electric power transmission and distribution from source to the user can be placed into three categories

High tension networks : Beyond 33 kV

Medium tension networks : upto 33 kV Low voltage networks : upto 1 kV

For over a century, impregnated paper insulated cables held the sway in all the above categories. Impregnated paper has excellent electrical properties. Moreover, it has capacity to withstand a high degree of thermal overload without excessive deterioration. But it's hygroscopic nature requires the provision of a metal sheath to prevent moisture contamination.

There was therefore a long felt need for power cable insulation material which has a combination of non hygroscopic nature of thermoplastic materials, electrical properties of polyethylene and operational advantages of impregnated paper.

XLPE (cross linked polyethylene) has come up as the dream material. Since several decades now, it has steadily replaced impregnated paper.

What is XLPE ?

Low density polyethylene polymer is a compound of carbon and hydrogen having linear molecular structure. These long chains being independent, slide with respect to one another, resulting thermoplastic property of the material.

                                                                                      Polyethylene

In cross linking process, these chains are randomly bonded to one another, thus converting the independent molecules to a three dimensional linked network. Now, slippage between molecular chains is prevented and material becomes thermosetting.

XLPE