How can communication cables be normal in harsh environments?
Source: Internet
Author: User
Ethernet is the undisputed overlord of the Internet world. It has been firmly occupying the territory of commercial office environments in recent years. The field of control and automation is also moving towards this open, standards-based technology. Do you think the cables used at the reception desk can also meet the demanding requirements of industrial process control and automation technology environments? In fact, COTS (Popular) 5e unshielded twisted pair (UTP) Ethernet cables are very fragile in terms of industrial standards. In addition to obvious physical damage, there are also more concealed and invisible electromagnetic/RF interference. What would happen if we wanted to lay non-reinforced commercial 5e type unshielded twisted pair cables on the plant floor?
Installation problem: using too much force to pull the commercial UTP will stretch the cable. The Business Standard sets a maximum pull capacity of 25 lbs. Before Pulling the cable, the cable is 100 feet. After pulling the cable, it may change to 100 feet 2 inch. Cable stretching may cause excessive signal loss (attenuation) and signal delay. These effects will limit the possible cable laying distance. When the cable is moved, the twisted pair wires may be dispersed, changing the distance between the wires in the center, resulting in imbalance. In this way, the line has more coupling effects (crosstalk) and signal echo transmission (return loss), which are more susceptible to the interference of peripheral electromagnetic/RF. Any of these factors may cause loss of cable transmission data, resulting in industrial interruptions or security issues. Belden CDT's patented stick wire pair technology can prevent the wire pair from being split, ensuring the design performance of the cable. The insulation conductors of each line are physically attached along the entire cable. No matter how you move it, the cable pairs will not be unintentionally separated during installation. The adhesion line also increases the mechanical strength, in addition to the mechanical stability, but also increases the tensile resistance.
Temperature Impact: the above problems are caused by the handling cable. In industrial applications, what problems will be encountered in extreme temperature environments? Extreme low temperatures make the cables hard, brittle, and difficult to use, especially when the cables are too brittle during installation. On the other hand, a very high temperature may degrade the plastic properties used in the cable, and the corresponding cable should be laid according to the expected temperature. The cable temperature rating is not the only factor. At 20 ℃ or higher, the attenuation of the COTS 5e cable increases by 0.4% for each increase of 1 ℃. At 60 ℃, the attenuation may increase by 16%. Currently, Belden CDT provides a DataTwist cable to enhance the anti-attenuation performance at high temperatures. On the other hand, users can lay short cables or expect strong signals so that they can be correctly received when they are subject to electromagnetic/RF interference. However, the cable margin height and the inherent anti-disturbance degree may have been damaged during installation. The patented adhesive line of Belden CDT can prevent changes caused by installation of pull cables, the promised performance can be guaranteed even when more circumstances are taken into account (such as rising ambient temperatures.
Ultraviolet radiation and sunlight: most commercial 5e cables are not used for outdoor use. When the cables are exposed to ultraviolet rays in the sun, the plastic jacket of the cables accelerates decomposition. The mechanical strength (I .e., separated) of the jacket begins to decrease, shortening the cable service life. Belden CDT's DataTwist product provides a SUN-proof cable jacket to ensure that they are durable in real-world applications.
Oil resistance: in the actual daily production activities, many parts need to be well lubricated to ensure smooth operation. The lubricating oil extracted from the oil is immersed in the COTS 5e cable, especially at high temperatures. The oil will cause the cable sheath to expand, lose the mechanical strength, and expose the internal core. The DataTwist cable provides a variety of oil jacket to meet your actual production needs.
Mechanical Force: Wear, shear, and crush: If you drive on the cable, the entire cable may be damaged. Ordinary commercial cables are not even spared. DataTwist cables all have industrial-grade cable sheaths, some of which have unique surface Sheaths that provide additional mechanical protection against wear and shear. The reinforced DataTwist product adopts interlocking Reinforced armor, and the adhesion line pair and the installable performance of Belden CDT ensure the toughness of the Ethernet cable.
Electromagnetic/RF interference, noise and shielding: it is the best choice to avoid potential interference sources. The first step is to stay as far away from interference sources as possible when laying cables, such as electric welders, switching relays or DC drives. What should you do when you try to control similar sources of interference, such as electric welding anthropomorphic machines? One way is to use optical cables. Optical cables can definitely avoid the impact of Electromagnetic/RF interference. If you are concerned about costs, complexity, or the toughness of optical cables, consider using a solution that shields 5e copper cables. Even a simple layer of aluminum foil shielding can provide significant anti-Electromagnetic/RF interference capability in the correct grounding.
Grounding: Correct grounding is the key to effective shielding. Ungrounded or incorrect grounding may reduce the shielding effect. The ideal shielding grounding should only have a unique contact. When the interference signal is coupled to the screen, the current will be imported into the earth to avoid the impact of the line under the screen. When both the near and remote ends of the shield are connected to the ground, a grounding loop may be formed. The potential difference between the near and remote locations forms a huge potential difference and corresponding current on the conductive shielding layer. Shielding the flowing earth current makes it an interference source that carries the signal.
Balance: highly balanced and stable UTP can provide great anti-disturbance performance. Each half of the line pair can be considered as a ring antenna. The other half of the continuous twist is opposite to the above wire in the direction. In an ideal balanced cable, the Alternating Polarity of the ring antenna will offset the interference of the online pair. The adhesive line provides the closest balance to the cables, especially when the cables are installed in a rough manner and suffer mechanical damage during routine use. When interference exists, the balance and stability of cables are the key to failure in Industrial Ethernet applications.
Industrial Standard: Open standardization is a major advantage of Ethernet. Any product can be designed to meet the IEEE minimum requirements.
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