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EuroWire – September 2009
80
technical article
In this way, not only can gel consumption
be reduced, but good water-blocking
performance of the cable can be
guaranteed.
Researchers performed the same experi-
ment on cables with tape armour. The
optimum gel parameters for a cable
with 23mm wide steel tape armour are
200×19×0.2mm (if the gel is sprayed
at intervals of 1m). Otherwise, either
the cable samples failed in the water
penetration test or the gel was likely to
overflow in the production.
After the optimum gel parameters had
been selected, researchers employed this
new method in a practical production of
cables with metal tape armour. The initial
pilot production and the following mass
production verified that the method was
quite effective since none of the cables
failed in the water penetration test after
the production.
In addition, five drums of cables with
steel tape armour and tape armour were
randomly chosen for further tests. First,
a temperature cycling test (-40º~+70º
two cycles, lasting for 12 hours at each
temperature point) was performed on the
cables. Then, a mechanical performance
test was carried out on the cables,
including items such as vibration, repeated
bending and torsion.
After that a water penetration test (3m long
cable sample, 1m waterhead, 24 hours) was
undertaken again to testify the reliability of
the method.
Table 2
shows the test items in mechanical
performance test.
Table 3
records the
water penetration test results after above
cable performance tests. The test results
show that after severe temperature cycling
and mechanical performance tests, the
water-blocking performance of the cables
made with this new method is still very
good. Thus it can be predicted that the
water-blocking performance of these
cables can be guaranteed within their
service life.
5 Conclusions
Generally, the water-blocking performance
at the overlap of the metal tape in
optical fibre cables cannot be absolutely
guaranteed in practical production. The
layer-by-layer method for cable gel filling
proposed in this paper can effectively
solve the problem. This method can be
easily implemented on existing sheathing
lines and it can reduce production cost by
using ordinary filling compound instead of
water-swellable gel along the cable core.
It can also save material by intermittently
injecting gel along the metal tape.
Moreover, researchers have foundoptimum
gel parameters through experiments to
minimise the gel consumption without
sacrificing the water-blocking performance
of the cable. The water penetration test
after the temperature cycling test and
the mechanical performance test of the
cable shows that this new method is
quite reliable and it will act as an excellent
solution for cable gel filling during the
production of cables with metal tape
armour.
n
6 Acknowledgements
Special thanks should be given to those
who gave their kind assistance to the
implementation of this method.
7 References
[1]
IEC-60794-1-2, Optical Fibre Cables Part 1-2:
Generic Specification-Basic
This paper was first presented at the
56
th
IWCS and is reproduced with the
permission of the organisers.
Yangtze Optical Fibre
and Cable Co Ltd
Wuhan, Hubei,
PR China
:
zhouzhenfu@yofc.comCable Sample
Vibration
(amplitude:
±3mm)
Repeated
bending
(load: 150N)
Torsion
(load: 150N)
Cables with
steel tape
armour
A
10 min
±90°
30 times
±90°
10 times
B
20 min
±90°
60 times
±180°
20 times
C
60min
±90°
100 times
±360°
100 times
D
60min
±90°
100 times
±360°
100 times
E
60min
±90°
100 times
±360°
100 times
Cables with
aluminium
tape armour
A
10 min
±90°
30 times
±90°
10 times
B
20min
±90°
60 times
±180°
20 times
C
60min
±90°
100 times
±360°
100 times
D
60min
±90°
100 times
±360°
100 times
E
60min
±90°
100 times
±360°
100 times
Table 2
▼
▼
:
Test items in mechanical performance test
Cable Sample
Gel parameters
Water penetration
test
Cables with
steel tape
armour
A
200x20x0.3mm
(at an interval
of 1m)
Passed
B
Passed
C
Passed
D
Passed
E
Passed
Cables with
aluminium
tape armour
A
200x19x0.2mm
(at an interval
of 1m)
Passed
B
Passed
C
Passed
D
Passed
E
Passed
Table 3
▲
▲
:
Water penetration test results after cable performance tests