The development history of shielding system has gone through thorns and seen the light again.
The debate is coming to an end
The debate between shielding and non-shielding has become calm because of the development of application, and the debate is no longer meaningful. It is wiser to focus on how to better meet the needs of applications.
In the field of wiring, the debate about shielded system and unshielded system began from the day when shielded system was born, and it was once intensified. The key point is that "the shielding system needs to be shielded everywhere, except cables, jumper panels, connector information ports and distribution frames, otherwise it is better not to be shielded." In order to achieve the so-called everywhere shielding, regardless of the product itself, high requirements were put forward for installation at that time.
In fact, it is generally believed that this debate is a dispute between two factions of manufacturers to some extent: American manufacturers advocate unshielded systems; Shielding systems are mainly advocated by European manufacturers. "In fact, the debate about shielded and unshielded systems has a long history, but one thing needs to be clear. It is wrong to think that TIA/EIA-568a (the telecommunications wiring standard for commercial buildings in the United States) is biased towards unshielded, and CENELECEN EN 50173 (the wiring standard promulgated in Europe) is biased towards shielded, because both the above standards and ISO/IEC16544. This view of Schneider Electric is different. However, with the internationalization of manufacturers, in order to meet the needs of more users, the debate between shielded and unshielded gradually faded, and most mainstream manufacturers also provide shielded and unshielded systems at the same time.
Simon's technician told the reporter, "The debate about shielded system and unshielded system is meaningless. The shielding system has matured, and the installation is no longer as complicated as expected. More and more users need shielding systems. We should look at how to meet the needs of different users from the product and application level. "
"At present, the industry generally holds a positive attitude towards shielding systems. Compared with unshielded system, shielded system has lower insertion loss, better crosstalk, ACR and return loss performance and better consistency.
When the signal is transmitted at high frequency in the line, if some measures are not taken, a large number of transmission errors will occur due to external electromagnetic interference and crosstalk of the cable itself, thus reducing the performance of the system. Shielding system can support safe and high-speed data communication in harsh electromagnetic environment, and better meet the requirements of users' high-performance applications for network wiring system and future network upgrade and expansion. "Tyco company related personnel think of shielding system.
In fact, in the reporter's investigation and interview, the overall style is consistent with the above-mentioned companies, and everyone generally holds a positive attitude towards the shielding system. The debate between shielded system and unshielded system seems to have changed because of the development of application, and the opinions gradually tend to be consistent.
Technology has been developing continuously.
Technically, the development of shielding system has been going on. Will shielding system become the mainstream in the future? Not impossible.
Shielding system is to ensure the transmission performance of the system in interference environment. Anti-interference performance includes two aspects, namely, the ability of the system to resist external electromagnetic interference and the ability of the system to emit electromagnetic interference itself. For the latter, Europe has passed the EMC specification, that is, the EMC test standard. At present, mainstream products can meet this specification, so in the usual environment, shielding system is mainly used in the former.
The general method to achieve shielding is to wrap a metal shielding layer on the outer layer of the connecting hardware to filter out unnecessary electromagnetic waves. With the deepening of application requirements, the shielding system itself is also developing. On the one hand, it is consistent with the overall development of the integrated wiring system, that is, the shielding system has experienced five categories, more than five categories (100MHz), six categories (250MHz) and even seven categories (600 MHz); On the other hand, from the technical aspect of the shielding system itself, there are three shielding methods in the shielding system at present: FTP, S-FTP and PiMF. PiMF can be called "independent" shielding mode (that is, each pair in a cable is shielded by shielding layer separately, and then all pairs are shielded by shielding layer), and its performance index is higher than the other two shielding modes. With the adoption of emerging high-bandwidth services and higher-speed Ethernet standards in the future, voice, data and video networks are more and more integrated into the basic lines, and the requirements for high security, high reliability and high performance of the networks are getting higher and higher. "Independent" shielding method will have more applications in the future.
With the development of cabling, at present, most users choose super-5 systems, and more and more users begin to choose 6 systems. With the development of video applications, the demand for bandwidth is getting higher and higher. When Gigabit to desktop becomes popular, 7 types of systems will naturally be favored by users. Need to remind everyone that due to the requirements of transmission performance, seven types of systems must be shielded systems. Does this mean that in the future, shielding system will become the mainstream of wiring?
In fact, when it comes to seven types of systems, it is natural to ask, "Will optical fiber gradually replace shielding systems?" Relevant personnel of Tyco Company analyzed this problem. "Although optical fiber has an advantage over copper cable in performance, optical cable wiring has the best network shielding effect and can obtain extremely high bandwidth and transmission rate, but the expensive price of optical fiber and the high requirement for engineering installation must be considered by users when choosing. At present, the installation cost of seven kinds of wiring systems introduced by many manufacturers is close to the cost of multimode optical fiber, but the cost of optical fiber network equipment is much higher than that of copper cable network equipment, which determines that if the overall price is compared, using optical fiber will be much more expensive than copper cable. Therefore, if the high price factor still exists, there is still a long way to go for optical fiber to replace the shielding system. "
The application becomes clearer and clearer.
Who is the main user group of shielding system at present? Do you need to choose a shielding system? How well do users accept the shielding system? What are the main reasons that affect users' adoption? It is necessary to know the answers to these questions.
Ren Gong, an integrator of Huijin Network Technology Group, which is very influential in the field of wiring, told reporters, "There are two types of users choosing shielding systems. One is users with serious electromagnetic interference environment, such as factories, radio stations, broadcasting stations, airports, subways, etc. Among them, we have run many factories and mines; The other category is units that strictly require confidentiality for security reasons, such as national defense, government, finance, etc. "
In fact, these two types of users choose the shielding system because the shielding system meets their respective needs and solves the electromagnetic interference problem in the former environment; It solves the problem that the information needed by the following business cannot be leaked. These two aspects are the advantages of shielding system different from non-shielding system.
"With the deepening of data concentration, the financial system needs more and more shielding. In addition, technological research frontier institutions such as universities and research institutes are also the scope of application of shielding systems. " The relevant personnel of Tyco made such a supplement. "For security reasons, many users in the government industry have adopted shielding systems, and the construction of a large number of government networks brought about by e-government has greatly promoted the development and application of shielding systems."
Is it necessary to choose a shielding system? Faced with such a problem, the relevant personnel of Tyco and Schneider Electric gave such an answer, "Why use a shielding system? Mainly consider the security of information and better anti-electromagnetic interference ability. At present, there are all kinds of electrical equipment and electronic equipment everywhere, and the operation of these equipment is mostly accompanied by the conversion of electromagnetic energy. High-density and wide-spectrum electromagnetic signals and electromagnetic energy fill our living space, and the electromagnetic interference formed constitutes an extremely complex electromagnetic environment. Simply put, as long as there is electricity, there will be electromagnetic radiation, which will produce different degrees of electromagnetic interference. Undoubtedly, shielding system has great advantages in anti-interference of transmission (especially at high frequency). Therefore, for the surrounding areas with strong electromagnetic interference, the shielding system should be considered first. It is mentioned in the design specification that when the external electromagnetic field exceeds 3V/m, shielding system or optical fiber wiring system should be considered. "
Indeed, the electromagnetic radiation around us is getting stronger and stronger, which we can't ignore, and it also provides a broader application opportunity for the shielding system to a certain extent.
What is the current user acceptance of the shielding system? What are the main reasons that affect users' adoption? "Users with high reliability and security requirements have a higher acceptance of the shielding system, and users will choose according to their own needs and actual conditions. Most users who do not use shielded systems are cost-conscious, and the overall price of shielded systems is higher than that of unshielded systems. In terms of cables alone, it will be nearly twice as high. " Jia Yongdong, an engineer of another integrator, Beijing Beian Building Intelligent Function Co., Ltd., said this. In fact, manufacturers and users have also expressed this view. Mr. Jiang Guo Muliang from the Information Center of Union Medical College Hospital also said that "non-shielding is cheaper than shielding, and it is necessary to analyze whether it is necessary to adopt shielding system in combination with specific application environment."
Installation is no longer a problem.
If the shielding system is suitable for you, what should you pay attention to when choosing and installing the shielding system?
What should users pay attention to when selecting and installing shielding system? Tyco said that users are advised to make a comprehensive balance according to their actual situation. If there are strong electromagnetic interference sources or high requirements for network security, shielding systems are needed. A complete shielding system needs shielding everywhere to achieve the desired effect of users. So if you choose shielding system, in addition to cables, modules, distribution frames and other connectors need shielding, supplemented by metal bridges and pipes. In addition, the installation of shielding system is complicated, and improper installation will not only fail to achieve shielding effect, but also cause greater interference. Therefore, users should first choose shielding products from regular manufacturers, and pay attention to choosing qualified and experienced companies when choosing companies for installation projects.
Indeed, the problem of shielding system installation is the most common, and it is recognized by the industry that shielding system has higher requirements for installation. When installing the shielding system, the shielding layer must be completely well grounded, so as to introduce the interference current into the earth.
"At present, the installation of shielding system is not as complicated as previously thought, the products are becoming more and more mature, and there are more and more engineers with installation experience. In specific projects, users will install in strict accordance with the requirements and pass strict tests, so there will be no problem. " Ren Gong of Huijin Network Technology Group said this.
In fact, in the face of high installation requirements, mainstream manufacturers have also adopted some effective methods to simplify the installation and reduce the difficulty of installation, such as the termination method of shielding system introduced by AMP, PowerCat with color code introduced by Molex and humanized design products introduced by IBDN. It seems an obvious trend that installation is no longer a problem as long as enough attention is paid to it.
Alternative application
Generally speaking, the function of the shielding system is to protect the information transmitted in the shielding system from interference and leakage, but when doing this topic, the reporter found a very interesting application in the user survey and interview, which is to use the shielding system to prevent the information transmitted in the cable from interfering with other equipment.
Mr. Jiang Guoliang from the Information Center of the Union Medical College Hospital told the reporter that some shielding systems were used in the wiring system of their hospital, mainly in the CT room and the nuclear magnetic room. Because CT equipment and nuclear magnetic equipment are very sensitive to signals, shielding system can prevent signals transmitted in cables from interfering with these equipment, because if interference occurs, the results of patient examination may be biased. In order to ensure safety, Union Medical College Hospital adopted shielding treatment.
Mr. Jiang also told reporters that Union Medical College Hospital attaches great importance to information construction. Although for cost reasons, most wiring systems adopt unshielded systems, laying metal trunking outside the unshielded systems also plays a shielding role in essence.
For the special application of Union Medical College Hospital, although the reporter knows that there should be provisions in the wiring standard for the electromagnetic interference generated by the shielded cable itself, there is still a question of "how much interference is caused by the information transmitted in the cable". Questions from several manufacturers generally say that there are strict regulations in the standard, and the information transmitted in the cable will not interfere with other equipment, such as ct equipment and nuclear magnetic equipment, which are extremely special products.
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