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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.
In the case of a twisted line the individual conductors of an electric circuit swap places, either in their whole course (at cables) or at certain points (at overhead lines). The mutual influence of electrical conductors is reduced by transposing. The unbalance of the line, which can lead to one-sided loads in three-phase systems, is also ...
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 25-pair color code, originally known as even-count color code, [1] is a color code used to identify individual conductors in twisted-pair wiring for telecommunications. Color coding [ edit ]
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 ...
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).
Balanced line in twisted pair format. This line is intended for use with 2-wire circuits. Fig. 2. Balanced line in star quad format. This line is intended for use with 4-wire circuits or two 2-wire circuits. It is also used with microphone signals in professional audio. Fig. 3. Balanced line in DM quad format.
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.