WCA July 2017

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68 Wire & Cable ASIA – JulyAugust 2017
Sikora AG
Bruchweide 2,
28307 Bremen,
Germany
Tel:+49 421 489 000
Email:
Website:
On- and offline inspection and analysis of
pellets, flakes and tapes/films
In addition to online inspection and sorting devices there
are modular designed systems available for on- and
offline inspection and analysis of pellets, flakes and tapes/
films. These are used for smaller throughputs as well as
production lines where sample testing is sufficient, or for
the control of incoming goods.
Depending on application, the systems are equipped with
X-ray technology (X), infrared technology (IR) or optical
sensors (V) to be used during the production or for sample
testing and detect contamination from 50μm. For example,
a laboratory inspection and analysis device with X-ray
technology (Figure 5) inspects up to 3,000 pellets (200ml)
that are placed on a tray.
Within seconds, these pellets are inspected for
contamination. Subsequently, contaminated pellets are
optically highlighted, which makes the extraction of the
individual contamination significantly easier.
For comprehensive process optimisation cable
manufacturers combine an online inspection and sorting
system with an offline inspection and analysis device.
Once contaminated pellets have been detected and sorted
out, the laboratory system inspects these pellets again and
marks contamination optically for an easy separation of all
rejects. This interaction of online and offline inspection and
analysis enables control of the material purity and allows
the creation of a database to prevent future contamination.
Conclusion
In summary, this paper outlined the reasons for the need of
a high purity degree of XLPE and HPTE material used for
the insulation of MV and EHV cables.
Furthermore, the paper introduced systems for on- and
offline quality control of XLPE and HPTE that inspect the
material before processing.
The presented inspection and sorting system detects
contaminated pellets and separates them before they get
into the extrusion process. The contamination may be
in the raw material, but may have also been added at the
handling and transport stage.
Accordingly, even if cable manufacturers keep on using
screens, this technology assures that screens are not
getting clogged with impurities from contaminated pellets
and allows, therefore, a longer and safe production run. By
using X-ray and optical technologies contaminants inside
and on the pellet surface are detected, which guarantees
100 per cent quality control.
With the use of an offline inspection and analysis system
for contaminated pellets that had been separated by the
online inspection system, production processes can even
be improved.
The material purity is controlled and the analysis gives
information to prevent future contamination.
Taking these advantages together, the use of the
introduced technologies for quality control of XLPE and
HPTE material is essential to assure high-quality MV and
EHV cables.
Simultaneously, by ensuring a high purity degree of XLPE
and HPTE material, cost for re-manufacturing cables that
failed the discharge tests can be saved and the efficiency
of the cable production line is improved to a great extent.
References
[1] Conference Paper in Electrical Insulation, 1988, Conference Record
of the 1988 IEEE International Symposium on July 2010, S Belli, G
Perego*, A Bareggi, L Caimi, F Donazzi, E Zaccone, Prysmian SpA,
P-Laser: breakthrough in power cable systems
[2]
[3] Chinese standard IEC 62067 (for 150-500kV) in J Kjellqvist, K P Pang,
S Miao, Dow Europe GMBH, Horgen, Switzerland, Dow Chemical
(China) Co Ltd, Shanghai, China, Performance Requirements to
Assure Reliable HV and EHV Cables, China International Conference
on Electricity Distribution (CICED 2010) Nanjing (20th-23rd September
2010)
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❍ Figure 5 : Offline inspection and analysis system