In the integrated wiring from the large categories to distinguish the two kinds of wiring way wrong wiring and shield the wiring two categories, shielding wiring way first originated in Europe, the main outside the common unshielded cabling system combined with metal shielding layer, the principle is to use metal shielding layer of emission, absorption, and skin effect to realize the function of preventing electromagnetic interference and electromagnetic radiation, the principle of comprehensive utilization of the twisted-pair cable shielding system balance and shielding layer shielding effect, so it has very good characteristics of electromagnetic compatibility (EMC).In addition, the shielding wire is also slowly showing advantages in electromagnetic compatibility. Currently, the cable industry in Europe, America, North America and other countries have already used this kind of wiring.
Based on block wiring can help on the advantage of the rapid development of Internet, many large data centers are shielded cabling systems, so using shielding after wiring system is one of the main trend of network cabling.Let's take a look at some of the issues related to the wiring in the network wiring.
First, what is EMC characteristics?
EMC is electromagnetic compatibility, which means that electronic equipment or network system has certain ability to resist electromagnetic interference, and can not produce excessive electromagnetic radiation.That is to say, the equipment or requirements of the network system can work normally in the electromagnetic environment is poor, and radiation are not excessive electromagnetic interfere with the normal work of the other surrounding equipment and network.
Second, how to measure the performance difference between a shield and a non-blocking system?
The advantage of the FTP cable shielding system is to provide better EMC performance than UTP cable, which is based on the isolation of the system from the external electromagnetic environment.Because the external electromagnetic environment can affect the whole wiring system data transmission.So far, there are no performance indicators or test methods to express or compare EMC performance.
The third and UTP cable is the ideal balance transmission system. Why use the FTP cable?
The UTP cable is used to achieve EMC performance through double stranded wire, which means that EMI is first received by UTP cable and then cancelled.However, as the frequency increases, the EMC performance of UTP will decrease.After measurement, the cable double stranded can only meet the EMC performance of 30MHz, which can be used for higher electromagnetic interference double stranded wires.So far, most actual network applications have less than 30MHz.
Moreover, the ideal balanced transmission system does not exist.The balance of the UTP cable is not only dependent on the quality of the component itself (such as wringing), but is affected by the surrounding environment.Because of the metal around UTP, the hidden "ground", the pull, bending and so on in the construction, the balance characteristics will be destroyed, thus reducing the EMC performance.
In fact, we install cables that are usually put into metal ducts, plastic catheters or other protections that have different grounding resistance.Therefore, there is only one solution to achieving a durable and unchanging performance: grounding all the cores with a layer of aluminum foil.Aluminum foil adds protection to the fragile double stranded conductor and creates a balanced environment for UTP cables.This means that the shield solution based on the FTP cable is ** in the environment, that is, regardless of the environment.FTP is a combination of UTP's balance characteristics and construction flexibility and STP shielding effect, which is the perfect combination of balance and shielding principle.
Fourth, what is the shielding principle of the FTP cable?
Unlike offset balance principle of twisted pair, FTP is outside of the four pairs of twisted-pair cable add one more layer or two layers of aluminum foil, using metal to the electromagnetic wave reflection, absorption and skin effect theory (the so-called skin effect refers to the distribution of electric current in the conductor cross section along with the rise of frequency distribution of conductor surface, the higher the frequency, the smaller the skin depth, the higher the frequency, electromagnetic wave penetration weaker), effective to prevent external electromagnetic interference into the cable, and also prevent the internal radiation signal, interference of other equipment work.
The experiment shows that the electromagnetic waves exceeding 5MHz can only pass through the aluminum foil of 38 mu m thick.If the thickness of the shield over 38 microns, such as Nike's FTP cable for two 25 microns thick layer of the aluminum foil shield, can through the shield made it onto the frequency of the electromagnetic interference of the main cable under 5 MHZ.For the low frequency interference of 5MHz, the principle of double stranded can be effectively offset.
Henan Sanheng Industrial Co., Ltd. , founded in 2000, It is one of the top wire and cable manufacturers in China's wire and cable industry for nearly 20 years. the company has more than 5 production lines., founded in 2000, It is one of the top wire and cable manufacturers in China's wire and cable industry for nearly 20 years. the company has more than 5 production lines.
The production cable can be divided into more than 50 varieties and subdivided into 1000 specifications.All products have passed national certification, such as China compulsory certification, bv certification, Nigerian SONCAP certificate, China national industrial certification, etc. China national industrial production license, etc.It also has the ability to produce products that meet international standards, such as iec, ce, rohs, etc.
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