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Shielding system question and answer
Time：
2015-07-31 15:53
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Shielding system question and answer
Q: Is it dangerous to use a shielding system?
A: No. If a TN-S system is used, the system is as safe as an unshielded twisted pair system. Poor grounding or poor power distribution systems can affect a variety of copper cabling systems. If using a TNC or TN-C system. Current will appear on the PE(N) line. If it is a screen
The system will have a current at the shield and the reference potential. If an unshielded twisted pair system is used, current will appear at the reference potential.
When a lightning strike occurs, the damage to the shielding system is much lower than that of the unshielded twisted pair system.
Q: I have a TN-C or TN-C-S system. How do I use the cabling system?
A: First measure the current on the PE in the power distribution system. If the potential difference is higher than 1V, equipotential lines should be installed between the distribution points. A more efficient method is to change the power distribution system. In both cases, the PEN line causes many problems.
Q: Should the shield be connected at one end or the shield at both ends?
A: It should always be connected at both ends (ie, on the patch panel and network equipment, not on the socket) to effectively suppress all electromagnetic compatibility mechanisms and avoid antenna effects.
Q: Do you have to use metal partitions in the cable ducts of the shielding system?
A: It is only required when the pipe length is more than 35 meters. For unshielded twisted pair systems, metal partitions must always be used.
Q: Is it enough to use an FTP cable? Is it better to use a PiMF cable?
A: From the point of view of electromagnetic compatibility and performance, PiMF cable is the best solution.
Q: Does the lightning strike also affect the unshielded twisted pair system?
A: Yes. Without any lightning protection system, the magnetic flux will be very strong, causing the pairs in the unshielded twisted pair cable to not suppress the signal. Lightning near the structure causes a 10,000-fold higher probability of internal system failure than a shielded system. This is described in IEC62305-2/FDIS.
Q: Can an unshielded twisted pair system meet electromagnetic compatibility requirements?
A: It is possible. There is no standard for electromagnetic compatibility of wiring systems today. Therefore, from a system perspective, there are no restrictions that must be met. The EMC Directive only requires the owner to be responsible for not interfering with other systems and not being disturbed by other systems. Some tests have shown that unshielded twisted pair systems cannot be satisfied
Requirements of EN 55022B. The standard is for residential and office environments.
Q: I have an unshielded twisted pair system. Do I need a grounding system?
A: Yes. Grounding is for safety. All electrical equipment within the SELV must be grounded at voltages above 25V AC, 60VDC or voltage. Even for fiber optic installations, a well-designed, fully functional grounding system is a must.
Q: I have an unshielded twisted pair system. Do I need an equipotential bonding system?
A: Yes. Equipotential bonding is for safety and all electrical installations must have equipotential bonding. In addition, it can improve electromagnetic compatibility. This applies to a variety of wiring systems.
Q: My system supplier provides an electromagnetic compatibility guarantee/compliance guarantee for my cabling system. Does this mean that I have fulfilled my responsibilities?
A: No. If the system is active, there is currently no clear meaning.
Q: My unshielded twisted pair system is wired to work together for protection. Is this enough to effectively suppress interference?
A: No. Intertwisting reduces interference but does not effectively eliminate interference. Intertwisting does not inhibit electromagnetic radiance. This is more serious if the cable is stretched or flattened during installation. Because the geometry is no longer uniform.
Q: I have an unshielded twisted pair system and want to improve my electromagnetic compatibility. how should I do?
A. The most effective way is to incorporate cables and components into the shielding environment. This environment can be shielded cable ducts and channels. Shielded racks and patch panels provide some basic protection. Note: All components must be connected to the equipotential bonding system.
Q: I have a shielding system and would like to use an unshielded patch cord. is it possible?
A: The system can work like a shielded patch cord. However, since there is no complete connection to the ground (only connected on the wiring board), there is no electromagnetic interference suppression capability. Therefore, shielded patch cords should always be used.
Q: What is the difference between grounding and grounding?
A: There is no difference, only two words of the same object.
This article is from the "Integrated Cabling Working Group" blog, please be sure to keep this source http://cteam.blog.51cto.com/358485/73839