CV-line (catenary line) with measuring equipment for reliable quality assurance during production of energy cables.

Photo: Sikora

Quality assurance during the production of energy cables

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There were more wind power plants built in European seas in 2010 than ever before. More than 300 plants with a total power of more than 880 megawatt were added. According to the European Wind Energy Association (EWEA), there will be strong investments in the future on the construction of new wind turbines at sea.
Power transmission from offshore wind parks to the mainland is currently being funnelled by undersea cables. These cables have to provide different requirements as well as environment conditions. Thus, the cable design complies with national and international standards. In order to fulfil these requirements cable manufacturers use innovative measuring and control technology in their production lines. This controls all cable specifications during the production. Sikora offers a band width of measuring technology for the use in CV-, VCV- or MDCV-lines.

In a CV-line, for example, a CSS 2 (Cleanliness Scanning System) is installed for real time monitoring and detection of impurities of the polymer melt. The flow channel between main extruder and the cross head is equipped with sight glasses and an optical CCD camera system, which transilluminates the insulation material. Thus, the system assures that only pure PE material is used for the cable production. As a result, a higher electric strength of the cable can be achieved.

Sikora’s product range for energy cables also includes the Ultratemp 6000, which measures the temperature of the PE melt during extrusion on a non-contact basis between the extruder screw and the cross head. Besides temperature determination, the Ultratemp 6000 detects inhomogeneities in the melt. Early cross linking after screens which may lead to ambers or scorches in the material do not occur. The device optimizes the output of a planned production time.
X-Ray 8000 NXT assures accurate hot measuring values of the cable parameters (3)
The X-ray measuring system X-Ray 8000 NXT is installed in the moving part of the telescopic tube directly after the crosshead for precise hot measurement of the wall thickness of all 3 layers (concentricity, diameter and ovality). Measuring values for centering and control are therefore available immediately after starting up the line. The system is used in catenary and vertical lines.

While the X-Ray 8000 NXT provides information for a fast centering and direct control, the X-Ray 8700 NXT supplies precise quality data about the final product. The X-Ray 8700 NXT measures the diameter, wall thickness and eccentricity and is suitable for all cable types with solid, stranded or Milliken conductor and with single, double or triple layer insulation. With the use of the X-Ray 8000 NXT at the beginning of the line for collection of the hot measuring values and the X-RayY 8700 NXT at the end of the line for measuring the cold values, 3 shrinking values are analyzed for every insulation layer of the cable. Consequently, an optimum process is assured.