Detailed explanation of grounding shielding techno

Detailed explanation of grounding shielding technology of wiring system

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shielding wiring system comes from Europe. It adds a metal shielding layer outside the ordinary unshielded wiring system, and uses the reflection, absorption and skin effect of the metal shielding layer to realize the function of preventing electromagnetic interference and electromagnetic radiation. The shielding system comprehensively utilizes the balance principle of twisted pair and the shielding effect of the shielding layer, Therefore, it has very good electromagnetic compatibility (EMC) characteristics. We can see that throughout Europe, most end users will choose shielded wiring system based on the difference between digital display and microcomputer

the shielded wiring system comes from Europe. It adds a metal shielding layer outside the ordinary unshielded wiring system, and uses the reflection, absorption and skin effect of the metal shielding layer to realize the function of preventing electromagnetic interference and electromagnetic radiation. The shielding system comprehensively utilizes the balance principle of twisted pair and the shielding effect of the shielding layer, so it has very good electromagnetic compatibility (EMC) characteristics. We can see that throughout Europe, most end users choose shielded cabling systems

at present, shielding has been recognized by more and more users, and its good performance in electromagnetic compatibility is also being recognized by more and more people. Therefore, shielded wiring products in the market are not limited to European products, and more and more manufacturers provide shielded wiring products. In the newly released North American wiring tia/eia-568-b standard, shielded cable and unshielded cable are used as the recommended media for horizontal wiring at the same time, thus ending the history of no shielding system in North America

common shielding questions and answers

ask: what is EMC

answer: EMC refers to electromagnetic compatibility, which means that electronic equipment or network system has certain ability to resist electromagnetic interference and cannot produce excessive electromagnetic radiation. In other words, the equipment or network system is required to work normally in a relatively harsh electromagnetic environment, and at the same time, it is not allowed to radiate excessive electromagnetic waves to interfere with the normal work of other surrounding equipment and networks

ask: UTP cable is an ideal balanced transmission system, why use FTP cable

answer: UTP cables achieve EMC performance through the twisted pair of core wires, which means that EMI is first received by UTP cables and then offset. However, with the increase of frequency, the EMC performance of UTP will decline. After measurement, it is found that the cable twisted pair can only meet the EMC performance of 30MHz, and there is nothing to do with higher EMI twisted pair. So far, the operating frequency of most practical network applications is lower than 30MHz

moreover, an ideal balanced transmission system does not exist. The balance characteristics of UTP are not only determined by the quality of the components (such as twisted pairs), but also by the surrounding environment. Because the metal around the UTP, the hidden "ground", the traction and bending in the construction will destroy its balance characteristics, thus reducing the EMC performance

in fact, when we install the cable, we usually thread it into metal conduit, plastic conduit or other protection with different grounding impedance. Therefore, there is only one solution to achieve permanent grounding performance: add an extra layer of aluminum foil to all core wires for grounding. Aluminum foil adds protection to the fragile twisted pair core wire and creates a balanced environment for UTP cables. This means that the shielding solution based on FTP cable is environment independent, that is, environment independent. FTP combines the balance characteristics and construction flexibility of UTP with the shielding effect of STP, that is, the perfect combination of balance and shielding principle

ask: what is the shielding principle of FTP to exchange piston and oil cylinder cables at the consumer factory

answer: different from the balanced offset principle of twisted pair, FTP cable adds one or two layers of aluminum foil on the outside of four pairs of twisted pair, using the principle of reflection, absorption and skin effect of metal on electromagnetic wave (the so-called skin effect refers to that the distribution of current in the conductor section tends to the distribution of conductor surface with the increase of frequency. The higher the frequency, the smaller the skin depth, that is, the higher the frequency, the weaker the penetration ability of electromagnetic wave), Effectively prevent external electromagnetic interference from entering the cable, and also prevent internal signal radiation from interfering with the work of other equipment

the experiment shows that the electromagnetic wave with a frequency of more than 5MHz can only be used to analyze the vibration fault of the electronic universal experimental unit as follows: the vibration speed of 3 #, 4 #, 5 #, 6 # measuring points is good, and the transmission is 38 μ M thick aluminum foil. If the thickness of the shielding layer exceeds 38 μ m. For example, nexen's FTP cable has two layers of 25 μ Due to the aluminum foil shielding, the frequency of electromagnetic interference that can enter the cable through the shielding layer is mainly below 5MHz. For low-frequency interference below 5MHz, the principle of twisted pair can be applied to effectively cancel it

Q: how do we measure the performance difference between shielded and unshielded systems

answer: the advantage of the shielding system of FTP cable is to provide better EMC performance than that of UTP cable. It is based on isolating the system from the external electromagnetic environment. Because the external electromagnetic environment will affect the data transmission of the entire wiring system. So far, there is no performance index or test method to express or compare EMC performance. It is gratifying that CENELEC has begun this work (nexen generic cabling system is involved), and coupling attenuation is defined as an index to measure EMC performance. This index has also been written into the second edition of international Cabling Standard iso/iec1181

nexen shielding wiring solutions

nexen is the inventor of FTP series cables and the leader of shielding technology. Its shielding products have been tested and certified by Delta, UL and ETL. The index of series wiring products is much higher than that of iso/iec11801, eia/tia568b and en50173 standards

nexen f2tp cable adopts the unique double-layer longitudinal aluminum foil shielding structure in the world, that is, two layers of 25um thick aluminum foil are longitudinally wrapped outside the UTP cable. This double-layer longitudinal wrapping structure can not only avoid small gaps in the shielding layer when the cable is bent or heated, but also reduce the transfer impedance, improve the shielding effect, and make the grounding (including shielding grounding and protective grounding) more convenient and reliable. This high-performance is also very convenient to install, and its outer diameter is only 6.35 mm. For electromagnetic waves above 10MHz, the mechanism of reflection, absorption and skin effect of the shielding layer is used to offset electromagnetic interference and electromagnetic radiation. The higher the frequency, the more obvious the effect of the shielding layer

from the perspective of electromagnetic compatibility (EMC), the shielding layer of the cable must be in surrounding contact with a large area of metal surface, that is, the so-called 360o grounding. In nexen's double-layer aluminum foil shielding system, it is only necessary to clamp the inner shielding layer on the clip ontm cable conductor frame of nexen's patented product, so as to ensure that the shielded cable can realize 360 ° surrounding grounding in the distribution frame and information socket, and will never produce the so-called "antenna effect". This clip ontm cable lead frame is integrated with the modular distribution panel

(this article comes from the Internet and is collated by Qianjia Zhike. If there is infringement, please contact to delete it.)

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