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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

Email

:

zhouzhenfu@yofc.com

Cable 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