wiredInUSA May 2017

would suffer from chemical sweat-out. Shelf life makes storing premix compounds a concern. Online dosing removes some of these restrictions and gives the cable manufacturer awider selection of peroxides and antioxidants. Online dosing offers a significantly longer shelf life, and using alternative peroxides can even result in increased extruder outputs and longer production runs. Maillefer’s Smart Dosing is a system for both antioxidant and peroxide dosing, consisting of two separate feeders with gravimetric loss in weight measurement for accurate dosing, that also ensures that cable insulation cleanliness will not be compromised. Smart Dosing has no impact on extruder stability, but is said to guarantee thorough distribution of injected ingredients and ensure high product quality. During development, model cables produced with online dosing of XLPE have shown good geometrical properties as well as excellent peroxide and antioxidant homogeneity in the insulation material. Underground record cable A record 640kV extruded DC cable system has been successfully tested and qualified by NKT Cables. The commercialization of the first 640kV extruded DC underground system will increase the maximum power transmission of cable systems by 20 percent, and allow better integration of distant renewable energy sources into global energy systems

with minimum energy loss. A single pair of 640kVDCcablescan transmit enoughgreen energy to supply three million households. Michael Hedegaard Lyng, president and CEO of NKT Cables, commented: “The development of interconnector grids globally represents some of the biggest infrastructure projects of our time, and we are proud to pioneer the associated technology. The interconnector market is expected to grow significantly and with this 640kV cable system we are underlining our leading position within this promising market.”

S S The 640kV extruded DC cable tested by NKT Cables

The new system will reach a transmission capacity of over 3GW, 20 percent higher than the existing top solution based on 525kV technology. The new system is technically and commercially qualified according to the international recommendation Cigré TB 496. The cables use the same design and utilize the same DC XLPE insulation material as the company’s 525kV cable system, and the accessories for the 640kV cable system are the same as for the 525kV system.

wiredInUSA - May 2017

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