Telephone cord
Telephone cable is a common name for telecommunication cables . Telecommunication cables are available within localities as underground cables for underground installation and as aerial cables and in the military sector as field cables . Installation cables are used for installation in buildings. The structure and core identification of telecommunication and installation cables can be different. The so-called long - distance cables are used to connect cities or greater distances.
Construction of telecommunication cables
The interior of telecommunication cables contains the individual wire pairs or wire quads, the stranding and identification of which are described in the following sections. All wires together are covered with a more or less complex protection and identification system made of paper, foils, threads and sheaths. This complex system is used for crosstalk attenuation , counting and protection of the cable.
In line technology, there are cables with different numbers of twin wires (DA) (one DA, i.e. two wires, is required for one connection). The smallest cable used to have six, today ten pairs (i.e. twelve or 20 wires), which are mostly used as house connection cables for houses with a maximum of two residential units. The largest cable has 2,000 pairs of wires (including eight reserve pairs, so 4016 wires). These cables, so-called local connection cables (Ovk), connect local exchanges with one another, or are used as feed lines for city districts or streets ( called main cables here and usually between 100 and 500 pairs thick) and in this case end in cable distributors (KVz). Since each wire pair can only be permanently assigned to a single telephone connection, this system is very inflexible. Therefore, these classic telecommunication cables with copper wires are no longer laid because of their low capacity. Instead, fiber optic cables are laid today, which, despite their much smaller cross-section, can transmit many times more data, but are also considerably more expensive.
There are two methods of protecting the cables from moisture penetration, especially in the ground.
1. Local connection cables are inflated with an overpressure (10 millibars). Due to the overpressure, air is blown against the penetrating moisture in the event of minor leaks in the cable jacket, so that no moisture can penetrate. If there is a loss of pressure, a sensor reports that air is escaping from the system. Then the cable is inflated with a special gas, which means that the leak can be found using search devices.
2. Branch cables (Vzk), the cables that form the third cable level and are used in the local area, are longitudinally water-protected. The cavities between the wire pairs are filled with petroleum jelly (in newer cables with wire insulation made of plastic) . If the cable is damaged, water only penetrates the cable jacket directly at the damaged point. The leak cannot be located. Older cables with paper insulation around the respective wires do not have any filling, which means that water penetrating the wires corrodes the wires more quickly and the telephone connections therefore fail faster than with plastic cables. However, leaks can be identified more quickly and the error can be eliminated.
Wire designation
The wire designations a and b are clear identifications of the individual wires per pair in the subscriber line (i.e. wire 6a corresponds to the first wire of the sixth pair, i.e. the eleventh cable wire in total). For an analog subscriber line ( ab-interface ) and for an ISDN - the base connection is a twisted pair is required in each case for an ISDN primary rate access , depending on the transmission method, one or two pairs. The respective terminals on the devices are usually marked with a and b or with 1a , 1b or 2a and 2b .
Germany
The telecommunication cables were previously used by the former Deutsche Bundespost in all areas of line technology and subscriber installation. Today, other types of cables are mostly used in house installations. This type of cable is still used for underground cables.
Identification of cables with stranding in bundles
With the J-2Y (ST) Y cables, two pairs of wires ( twin wires) form a star quad or four for short . The cores of the star quads have a black ring marking in addition to the same basic color:
- Basic color without further marking: two-wire 1a / four-wire a
- Basic color with a black ring: two-wire 1b / four-wire b
- Basic color with two rings with a long distance to the next two rings: two-wire 2a / four-wire c
- Basic color with two rings with a short distance to the next two rings: two-wire 2b / four-wire d
- Distance between the individual rings / double rings: 1b 17 mm, 2a 34 mm, 2b 17 mm
The basic colors are, in order, red, green, gray, yellow and white. The arrangement according to this color scheme, in contrast to the other color counting systems, enables a person with color vision defects to find the count based on the brightness of the four (from red = dark to white = light).
- Five star quads combined form a bundle of ten, called a basic bundle .
- Five or ten basic bundles for higher-pair cables are stranded to form the main bundle with 50 or 100 pairs .
- The main bundles are stranded to form the telecommunication cable (with main cables up to 2000 twin cores).
To differentiate between the individual bundles, the first basic bundle, or the first main bundle, is given a red plastic spiral for each layer, all others a white or natural color. The individual basic bundles are counted from the inside to the outside and clockwise from the exchange looking towards the subscriber . ( Note : cable solderers are not stupid: office in the back, right around; office in the stomach, left is also possible ).
Identification of cables with stranded layers
Cables of this type were laid in front of stranded cables and are often so-called "lead cables " or "steel shaft cables " or "paper cables ". This is derived from the wire insulation made of paper and the cable jacket made of lead or corrugated steel. In contrast to cables that are stranded in bundles, they are not divided into bundles; instead, the counting is based on the individual layers of the cores from the inside out. Here, too, the individual cores receive the above. Barcode, and sometimes also a basic color. Before the introduction of the basic color, the first wire of each layer had a purple instead of a brown paper for insulation; it thus marked the "counting four", with which the cable could be counted clockwise or counter-clockwise (see motto "office in the back - right around" or "right-hand rule"). This stranding required a higher level of skill on the part of the telecommunications technician when counting due to the lack of coils and bundles. It should also be noted that so-called reserve wires, which were not included in the count, were present in cables with higher pairs.
In the private sector they are still used today in a different form. There is for example:
- Installation cable JY (ST) Y 2 × 2 × 0.6 with two pairs of wires with a wire diameter of 0.6 mm
- Installation cable JY (ST) Y n × 2 × 0.6 with number n twin cores with core diameter: 0.6 mm
It is counted in layers, from the outside to the inside, according to the color of the b-core . The order is: blue - yellow - green - brown - black . The exception is the 2 × 2 cable, where blue has been replaced by black. The a-wire is always white, except for the first pair of a layer, where the a-wire is red. If there are eight or more pairs of wires, there are two red wires because there are two layers.
Marking of cables with stranded layers - switching cables
Switching cables are used for device cabling, but also for other purposes in installations. There are
- Switching cable n × 2 × 0.4 with number n twin wires
It is counted in layers, from the outside to the inside, first according to the color of the b-core , then in bundles of 5 according to the color of the a-core . The order is: blue - yellow - green - brown - black . The a-wire is always in the respective bundle color, the first bundle color is blue, the second yellow etc.
Switzerland
The telecommunication cable U72 is mainly used in buildings as a telephone and low-voltage line. In the designation, U means: universal cable, 72: year of manufacture 1972. The cable is now manufactured with halogen-free insulation, the structure is a quadruple layout, just like in Germany. Five star quads combined form a bundle with a total of 20 wires.
| four | a wire | b wire | c wire | d wire |
|---|---|---|---|---|
| 1st foursome | White | blue | turquoise | violet |
| 2. foursome | White | orange | turquoise | violet |
| 3rd foursome | White | green | turquoise | violet |
| 4. Foursome | White | brown | turquoise | violet |
| 5. Foursome | White | Gray | turquoise | violet |
With the next bundle of 5 up to 10 × 4, the a wire is red , the other colors remain.
With the next bundle of 5 up to 15 × 4, the a wire is black , the other colors remain.
With the next bundle of 5 up to 20 × 4, the a wire is yellow , the other colors remain.
Austria
The cable is mainly used in buildings as a telephone and low-voltage line. Depending on the requirements, it contains at least two pairs of wires (DA). The type of cable used is usually a F-YAY n × 2 × 0.6 mm, which corresponds to a German JY (St) Y cable.
| THERE | a wire | b wire |
|---|---|---|
| 1st DA | blue White | blue |
| 2nd DA | blue White | yellow |
| 3rd DA | blue White | green |
| 4th DA | blue White | brown |
| 5th DA | blue White | black |
If there are more than five pairs, only the a-wire changes, the colors of the b-wire remain the same. "Sunflower field" serves as a catchword for the color sequence: above the BLUE sky; then the YELLOW sunflower; with the GREEN stem; underneath the BROWN earth and at the very bottom it is BLACK.
| Twin cores | a-core |
|---|---|
| 1-5 | blue White |
| 6-10 | yellow white |
| 11-15 | green white |
| 16-20 | brown / white |
| 21-25 | black-and-white |
| 26-30 | blue red |
| 31-35 | yellow Red |
| 36-40 | green red |
| 41-45 | brown / red |
| 46-50 | black red |
If a cable has more than 50 pairs, the color code starts again with blue / white - blue. A distinction between the paired wires 1–50 and 51–100 (possibly also above) is achieved by the position in the cable, the 51st pair is located significantly further inside the cable than the 1st pair.
Star-quad stranding is used for telecommunication cables outdoors. Four cores (white 1a, red 1b, green 2a and blue 2b) are stranded to form a “four”, whereby the first “four” is identified in each layer by a black instead of a white core.
| Vein | colour |
|---|---|
| 1a | white / counter = black |
| 1b | red |
| 2a | green |
| 2 B | blue |
commitment
Today's specifications of the network operators demand very high quality and high bandwidth from telecommunication cables in order to achieve large ranges for DSL transmissions .
The connection of two or more cable ends is called " splicing ".
