Twisted pair cable

Twisted pair cable is one that consists of one or more colour cable pairs of copper conductors covered by insulation.  The copper wire may be solid or stranded. Twisting of the pairs is to eliminate cross talk in the cable. Twisted pair cable reduces signal interference from external sources or sometimes from neighbouring pairs. 

The noise interference depends on the number of turns per foot. Increasing the number of twists decreases noise interference.

Purpose:

The purpose of twisted pair cable is to reduce the effect of electromagnetic interference on any kind of signal.

Types of Twisted pair cable

The basic division of cable is Shielded Twisted pair and Unshielded Twisted pair.  

According to ISO/IEC 11801, cable construction looks in the following way.

U/UTP – Unshielded twisted pair

F/UTP – Shielding made up of Aluminum foil around all twisted pairs.

SF/UTP – It indicates Foil and braid screened with unscreened balanced elements.  

U/FTP – Shielding around the twisted pairs individually, instead of wrapped around all pairs.

F/FTP – Both general shield on each pair with Aluminium foil and general shielding with copper.

S/FTP – Individual shielding of each pair made of aluminum foil and general shielding with copper braiding. It is double shielded on each pair.

Unshielded twisted pair cable

Unshielded twisted pair cables have been classified into different categories. These standards especially formulate the data capacity of the core.  Higher categories are more expensive than lower category cables.

Cat 1 – is a voice grade copper cable. Typically used for Telephone wires.  

Cat 2 – data transfer rate is 4 Mbits/s.

Cat 3 – data transfer rate is 16 Mbits/s.

Cat 4 – data transfer rate is 20 Mbits/s.

Cat 5/5e – Cat 5e is enhanced specification of Cat 5. The data rate is 1000 Mbit/s. It is most popular in process industrial applications. Widely used for local networks and video streaming.

Cat 6/6A– data transfer rate is 10 Gbits/s with a distance of 100 meters.

Advantages:

•           UTP cable is cheaper in cost.

•           Easier to install as they have a small diameter.

Disadvantages:

•           Prone to Electromagnetic interference.

•           Used for shorter distances because of attenuation.

•           Higher diameter than STP cable.

Applications:

Used in LAN connections.

Shielded twisted pair cable

As the name indicates, the cable is surrounded by the shield (typically copper braid or aluminium foil) at individual pair or all pairs together or sometimes pairs and cable also.

Advantages:

•           Reduces cross talk and provide protection from interference.

•           Shielding provides better electrical characteristics. 

Disadvantages:

•           Shielding increases the overall diameter

•           Shield to be properly grounded, otherwise, it acts as an antenna and picks up unwanted signals.

•           Cost of the cable is more than UTP.

Applications:

Used in industrial applications as Instrumentation cables.