XLPE Screenings and Insulation by Extrusion

Conductors made through stranding process are subjected to this operation to form cores. The process requires three extrusion operations, which are done simultaneously using three extruders but a common head.

The core consists of three concentric layers of extruded material. The first is a layer of black semi conducting compound formed over the stranded compacted conductor using the first extruder. Just on top of this a layer of white insulation compound is extruded to form the second layer and finally through another extruder a layer of black semi conducting compound is extruded over insulation layer. The semi conducting layer formed over conductor is called conductor screen and the one over insulation is called insulation screen. The three layers i.e .conductor screen, insulation and insulation screen are formed through a common head known as triple head.