Views:2 Author:Site Editor Publish Time: 2019-05-27 Origin:Site
When choosing cable and connector combinations for interconnect solutions in industrial applications, it's important to carefully consider the environment. Industrial equipment and processes that contain drives, solenoids, motors, generators, transformers, electrolytic processes, and power lines located within steel mills, telecommunication facilities, automotive, public safety environments, and other manufacturing plants or environments are conducive to electromagnetic interference through radiation or conductivity. The electromagnetic interference (EMI) that is generated from the use of equipment can result in catastrophic failures putting suppliers,customers, and consumers at risk. In medical, automotive, and aerospace applications, this risk can be life threatening.
In order to reduce the risk of EMI, cables and connectors are often shielded. Shielding is an enclosure for insulated conductors that may consist of braided strands of copper or a layer of conductive polymer which is surrounded by a plastic jacket.The shielding can act as a reflector of energy or as a grounding point to the electrical source by surrounding the power-carrying conductors. For cables, typical shielding types are foil and braid. Foil shielding provides coverage to the entire conductor it surrounds and is relatively inexpensive. Due to the thin nature of the foil, it is more difficult to work with and the majority of foil shielded cable applications utilize a drain wire in order to terminate and ground the shield. Braided shielding is typically copper or tinned wire that has been woven into a mesh that surrounds the conductors. Unlike foil shielding, braided shielding does not offer 100% coverage of conductors.Despite the lack of coverage to the entire conductor surface, the higher level of conductivity present in copper as compared to aluminum (aluminum is approximately only 60% as conductive as copper) makes braided wire a more effective option for shielding.
Shielding for network applications was first introduced in the 1980’s in twisted-pair configurations where the wires were shielded using foil. The combinations of the twisted-pair and the shielding resulted in performance levels that surpassed any prior developed cables. Today, shielded cables and connectors can be found in various configurations with wide range of product offerings. Configurations include single ended, double ended, or with multiple legs or “T” assemblies ranging from 0.5 A through 23 A, 28AWG through 12 AWG, and with 2 through 16 contacts.
Unshielded twisted-pair cable
Unshielded twisted-pair cable does not rely on physical shielding to block interference. It relies instead on balancing and filtering techniques using media filters, baluns or both. Noise is induced equally on two conductors and is canceled out at the receiver. With properly designed, manufactured and installed UTP cable, the network is easier to maintain than one in an STP cable plant, with its shielding continuity and grounding issues.
UTP cable has evolved during the years, and different types are available for different needs. Basic telephone cable, also known as direct-inside wire, is still available. Improvements over the years--variations in the twists or in individual wire sheaths or overall cable jackets--have led to the development of Category 3 cable that is compliant with the Electronic Industries Association/ Telecommunications Industry Association-568 standard for transmission rates up to 16 megahertz. Category 4 UTP cable is specified for signal bandwidths to 20 MHz, and Category 5 UTP for specifications to 100 MHz--and possibly higher.
Because UTP cable is lightweight, thin and flexible, as well as versatile, reliable and inexpensive, millions of nodes have been, and continue to be, wired with this cabling medium.This is especially true for high-data-rate applications. For best performance, this UTP cable should be used as part of a well-engineered structured cabling system.