| | | A wide variety of high voltage cable designs is offered by nkt cables to provide most economic solutions. Various types of conductors, insulation, metallic screening and sheathing, corrosion protective layers etc. are available. Conductors The cable conductors can be made of copper or aluminium. The choice is a matter of customer's preference or current carrying capacity. Large size solid conductors are made of aluminium. Available conductor constructions: V round solid conductors up to 2000 mm2 (RE) V circular stranded compacted conductors up to 1200 mm2 (RM) V circular conductors with shaped wires up to 2000 mm2 (RM, Keystone conductors) V segmental conductors up to 2500 mm2 (RMS, Milliken conductors) V oval shaped stranded compacted conductors up to 800 mm2 for external gas pressure cables (OM) The conductors are manufactured to meet the requirements of the relevant national and international standards. For special applications the conductors can be made watertight. Insulation The insulations for low pressure oil filled cables and for conventional pipe type cables are lapped from high quality insulating papers. Subsequently the paper insulated | | cable cores are impregnated in appropriate vessels with low viscous oil or high viscous compound. together with latest process control equipment and combined with decades of experience ensure manufacture of cables meeting the highest requirements and enabling development of most advanced power cable systems. Metallic Covering Conventional paper insulated cables require a pressure proof and watertight metallic enclosure, acting also as metallic screen. At nkt cables both, extruded lead sheath as well as the aluminium sheath can be applied. These types of metal sheaths are, of course, | | also used on XLPE insulated cables. While the lead sheath leads to smaller dimensions, the aluminium sheath provides high short circuit current carrying capability and lower weight. As the XLPE insulated cables do not require an internal overpressure, they are usually equipped with a copper wire screen. For radial moisture barrier a coated aluminium foil is longitudinally applied. The combination with the polyethylene oversheath is called aluminium polyethylene laminated (APL) sheath. This solution provides high short circuit capability and watertightness combined with lowest weight and smallest dimensions. A combination of the copper wire screen with a metal sheath is also possible. For all XLPE insulated high voltage cables, the space between cable core and water barrier is made longitudinally watertight. | | |