Ericsson ECN330 Manuel d'utilisateur télécharger pdf (Page 14)

Figure 2, Core structures. [4]

Figure 2 shows the different core structures. After the secondary coating,

there are three types of core structures. In standard lose tube the secondary

coated cables are around a central element. The cable can be tight or loose.

It depends on the secondary protection. The first optical cables were loose

tube design and it still is a very popular cable. Next there is the single tube

design. The heart of the cable is a strength member. Inside the strengthen-

ing member there are primary coated cables in a loose formation. The di-

ameter of the pipe is around 5-10 mm. This design has a very good crushing

protection. This is achieved by placing strengthening members inside the

jacket and the core. The third design is called slotted core. The core is a

plastic rod that has slots for the primary coated cables. This design has a

good crushing strength and installing it is simple. This is because it has easy

access to the fibres. One can take the fibres out one by one or in groups. In

the center of the cable is a pulling element. [3]

3.3 Pulling Element and Strength Members

When installing fiber cable, it is pulled. The pulling will usually break the

glass fibers, so some protection against it is needed. The protection has to

be strong enough so that the cable can be moved without breaking the

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Ericsson ECN330 Manuel d'utilisateur Page 14