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Twisted-pair cabling was invented by Alexander Graham Bell in 1881. [4] By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference. Today, most of the twisted pairs in the world are outdoor landlines, owned and maintained by telephone companies, used for voice service.
The pattern then starts over with the first 25-pair group as white/blue, and continues indefinitely, in multiples of 600 pairs or parts thereof. For example, a 900-pair cable has the first 600 pairs in 24 groups of 25 pairs in a white binder, and the remaining 300 pairs in 12 groups of 25 pairs wrapped in a red binder. [5] [6]
Typical values of Z 0 are 50 or 75 ohms for a coaxial cable, about 100 ohms for a twisted pair of wires, and about 300 ohms for a common type of untwisted pair used in radio transmission. Propagation delay is proportional to the length of the transmission line and is never less than the length divided by the speed of light .
The 20-pair colour code is a colour code used in Australia to identify individual conductors in a kind of electrical telecommunication wiring for indoor use, known as twisted pair cables. The colours are applied to the insulation that covers each conductor. The first colour is chosen from one group of five colours.
For cables, the swapping is gradual and continuous; that is the two or three conductors are twisted around each other. For communication cables, this is called twisted pair . For overhead power lines or open pair communication lines, the conductors are exchanged at pylons, for example at transposition towers or at utility poles , respectively.
Category 5 cable that is partially stripped and showing its four twisted pairs (eight wires). Category 5 cable (Cat 5) is a twisted pair cable for computer networks.Since 2001, the variant commonly in use is the Category 5e specification (Cat 5e).
R and L are elements in series with the line (because they are properties of the conductor) and C and G are elements shunting the line (because they are properties of the dielectric material between the conductors). G represents leakage current through the dielectric and in most cables is very small. The word loop is used to emphasise that the ...
An electrical cable is an assembly of one or more wires running side by side or bundled, which is used as an electrical conductor to carry electric current. Electrical cables are used to connect two or more devices, enabling the transfer of electrical signals , power , or both from one device to the other.