Technical Questions and Answers about the shielded Cabling System

There are still many things worth learning about the shielded cabling system. Here we will explain some common problems of the shielded cabling system in the form of a Q &, this includes an introduction to EMC and the principle of the shielded wiring system. We hope to provide you with more knowledge.

The shielded cabling system originated from Europe. It adds a metal shielding layer to the outside of a general unshielded cabling system, the function of preventing electromagnetic interference and electromagnetic radiation is realized by using the reflection, absorption and skin effect of the metal shielding layer. the shielding wiring system comprehensively utilizes the balance principle of twisted pair wires and the shielding effect of the shielding layer, therefore, it has excellent electromagnetic compatibility (EMC) features. We can see that most end users in Europe choose to block cabling systems.

At present, the shielded cabling system has been recognized by more and more users, and its good electromagnetic compatibility performance is also being recognized by more and more people. Therefore, the products of the shielded cabling system on the market are not limited to European products, but more and more manufacturers are offering shielded cabling products. In the latest release of the North American wiring TIA/EIA-568-B standard, shielded and unshielded cables are also used as a recommended medium for horizontal wiring, ending the history of North America's unshielded cabling systems.

FAQs about the shielded Cabling System

Q: What is EMC?

A: EMC is electromagnetic compatibility. It refers to the ability of electronic devices or network systems to resist electromagnetic interference and prevent excessive electromagnetic radiation. That is to say, it is required that the device or network system work normally in a harsh electromagnetic environment, and that the electromagnetic waves cannot be excessively radiated to interfere with the normal operation of other equipment and networks.

Q: The UTP cable is an ideal balanced transmission system. Why do I need an FTP cable?

A: The UTP cable achieves EMC performance through a twisted pair of core wires, which means that EMI is first received by the UTP cable and then offset. However, as the frequency increases, the EMC performance of UTP will decrease. After measurement, it is found that the cable twisted pair can only meet the EMC performance of up to 30 MHz, and there is nothing to do with higher electromagnetic interference twisted pair. So far, most actual network applications work at a frequency lower than 30 MHz.

In addition, the ideal balanced transmission system does not exist. The UTP cable balance is not only determined by the quality of the components, such as twisted pairs), but also affected by the surrounding environment. This is because the metal around UTP, concealed "Ground", pulling, bending, and other conditions will undermine its balanced characteristics, thus reducing EMC performance.

In fact, our installation cable is usually used to penetrate it into a metal catheter, plastic catheter, or other protection with different Grounding Impedance. Therefore, there is only one solution to achieve permanent ground-to-ground performance: grounding with multiple layers of aluminum foil on all core wires. Aluminum Foil protects the fragile twisted pair core wires and creates a balance environment for UTP cables. This means that the solution for the FTP cable-based shielded cabling system is independent of the environment, that is, it is not related to the environment. FTP is a perfect combination of UTP's Balance Characteristics, construction flexibility, and STP shielding effect, that is, the balance and the principle of the shielded wiring system.

Q: What is the principle of the FTP cable shielding and wiring system?

A: Unlike the balanced offset principle of twisted pair, the FTP cable adds one or two layers of aluminum foil to the outer of four pairs of twisted pair cables, the principle of the reflection, absorption, and skin effect of metal on electromagnetic waves the so-called skin effect refers to the distribution of current in the cross section of the conductor tends to the surface of the conductor with the increase of frequency, the higher the frequency, the smaller the skin depth, that is, the higher the frequency, the weaker the electromagnetic wave penetration ability), effectively prevent external electromagnetic interference from entering the cable, and also prevent internal signal radiation, interfere with the work of other devices.

The experiment shows that the electromagnetic wave with a frequency greater than 5 MHz can only pass through the aluminum foil with a thickness of 38 μm. If the thickness of the shield layer exceeds 38 μm, for example, the FTP cable of nexson is shielded by two layers of 25 μm thick aluminum foil, so that the frequency of electromagnetic interference that can pass into the cable through the shielding layer is below 5 MHz. The principle of twisted pair can be used to effectively offset low-frequency interference below 5 MHz.

Q: How do we measure performance differences between shielded and unshielded systems?

A: The advantage of the FTP cable shielding system is that it provides better EMC performance than UTP cables. 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 are no performance indicators or test methods to express or compare EMC performance. It is pleased that the European standardization Commission CENELEC has begun this work with the participation of nexson integrated cabling systems), coupled attenuation coupling attenuation, which is defined as an indicator for measuring EMC performance. This indicator is also written into the second version of the International cabling standard ISO/IEC11801.

Nexson shielded cabling system solution

Nexson is the inventor of the FTP series cable and a leader in shielding technology. All of its shielding products have been tested and certified by DELTA, the independent Danish Electronics Laboratory, UL, and ETL testing institutions in the United States. The indicators of series cabling products are much higher than the ISO/IEC 11801, EIA/TIA568B and EN50173 standards.

The nexson F2TP cable adopts the unique double-layer longitudinal aluminum foil shielding structure in the world, that is, the outer section of the UTP cable is divided into two layers of 25um aluminum foil, this double-layer longitudinal package structure can avoid slight gaps in the shield layer during cable bending or heating, reduce the transfer impedance, improve the shielding effect, and at the same time make the grounding including shielding grounding and protecting grounding) more convenient and reliable. This high-performance shielded cable is also very easy to install, and its outer diameter is only 6.35mm. For electromagnetic waves over 10 MHz, electromagnetic interference and electromagnetic radiation are offset by the reflection, absorption, and skin effect of the shielding layer. The higher the frequency, the more obvious the effect of the shielding layer. Low frequency (<5 MHZ) electromagnetic waves are offset by the balanced nature of twisted pair wires. This double-layer aluminum foil shielding cable has two major features: Superior shielding and wiring system performance, and convenient installation.

From the perspective of EMC), the shielded cabling system layer of the cable must be in contact with a large metal surface, that is, the so-called 360o Grounding (Grounding ). In the dual-layer aluminum foil shielding and wiring system of nexson, you only need to put a shield layer in the Clip-onTM Cable Guide Frame of nexson patented product, ensure that the shielded cable is Grounding around the ground at 360 ° in the distribution frame and information outlet. This will never produce the so-called "antenna effect ". This Clip-onTM Cable Guide rack is integrated with a modular distribution board.

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