Reducing contaminants that provide initiation points for trees can be expected to deliver better cable performance. Today s medium-voltage insulation materials are much cleaner than those of 20 years ago. Laser scanner technology can detect very small contaminants in the insulation. Identification of contaminants has led to greatly reduced contamination levels, and specifications on contaminants have become much tighter since the 1970s. Current laser scanning equipment can detect contaminants in XLPE down to 25 microns.
Laser scanners can also detect non-uniform material.
If a situation in the reactor where the compound is manufactured causes a non-uniform condition or scorching of the compounds, these defects can be detected and process corrections made. Once it s clean, keep it clean The entire insulation manufacturing environment has also seen significant improvements. The clean insulation compounds have to be kept clean during packing, shipping, movement in the cable plant and during extrusion. At the compound manufacturing end, that calls for measures such as clean-room conditions for packaging, packaging that eliminates fiber contaminants, and dedicated clean hopper cars. There have also been many improvements in the actual cable manufacturing over the past 20 years.