Splicing (telecommunications)

Splicing is a special way of connecting electrical lines or two glass fibers in telecommunications technology . Splice points are often placed in sleeves to protect them from external influences .

Splicing of copper wires

Splice point of a copper wire.

Cable sleeve (lead sleeve) for connecting paper-insulated wires, with insulating sleeves over the beads (right).

The splicing of copper wires is done in the following steps:

1. Lay the wires on top of each other at the connection point.
2. Loop the wire around each other two or three times ( twist ).
3. Remove wire insulation.
4. The bare wires are "twisted" or "twisted" over a length of approx. 3 cm. In some cases the knot is soldered.
5. To isolate the splice point (also called "bead"), an insulating sleeve made of paper or plastic is pushed over the bead.

The splicing of copper wires is mainly used for paper-insulated wires.

For connecting copper wires are usually LSA techniques applied (LSA: L öt-, S chraub- and A bisolierfrei) with which the copper wires are to be connected quickly and easily. LSA techniques are for example:

• Wire connection sleeves (AVH) and other compression connectors; the two wires to be connected are inserted into the AVH without being stripped , which is then pressed together with special pliers. The approximately 2 cm long AVH consist of a contact, pressure and insulating part.
• With wire connection strips (AVL) several pairs of wires (10 = AVL10 or 20 = AVL20) are inserted, the strip is then closed with a cover and pressed together with a hydraulic press, whereby the connection is ensured by this process.

Fiber optic splicing

Splicing of glass fibers using thermal fusion splice

Fiber optic cable sleeve (right) and splicer (left)

Glass fibers ( optical waveguides ) are spliced ​​with a special arc splicer, whereby installation cables are connected at their ends with respective “pigtails” - short individual fibers with fiber optic connectors at one end. The splicer adjusts the light-conducting cores of the two ends of the glass fibers to be spliced ​​to one another with pinpoint accuracy. Adjustment takes place fully automatically with modern devices, with older models manually using micrometer screws and a microscope. A trained splicer can position the fiber ends precisely within a few seconds. The fibers are then fused ( welded ) to one another with an electric arc . Since no additional material is added here, as is the case with gas welding or soldering, it is called a “fusion splice”.

Depending on the quality of the splicing process, attenuation values ​​of around 0.3 dB are achieved at the splice points, and below 0.02 dB with good splices. In the case of devices of the newer generation, the alignment is carried out automatically by motors. A distinction is made between core and shell centering. With core centering (usually with single-mode fibers) the fiber cores are adjusted to one another. Any core misalignment compared to the jacket is corrected. With sheath centering (usually with multimode fibers), the fibers are aligned with one another by means of electronic image processing before the splice.

When working with good equipment, experience shows that the attenuation value is max. 0.1 dB. Measurements are made using special measuring devices, etc. a. Optical Time Domain Reflectometry (Optical Time Domain Reflectometry - OTDR), performed. A good splice connection should have an attenuation of less than 0.3 dB over the entire route. Finished fiber optic splices are placed in splice boxes.

One differentiates:

• Fusion splice
• Adhesive splice
• Crimp splice or NENP (no-epoxy no-polish), mechanical splice

Individual evidence

1. ↑ Crimp splice on itwissen.info, accessed on April 21, 2017.

literature

• Andrew D. Yablonx: Optical fiber fusion splicing . Springer, Berlin, Heidelberg, New York 2005, ISBN 978-3-540-23104-2 .