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There are two protective requirements for optical fibers in formation of the fiber optic cables: one is less stress on optical fibers; the other is waterproof of optical fibers.

The outermost layer of the cable is a plastic sheath, and the inside is a metal sheath, and more inside is a water-blocking layer expanded by water. The core of the cable is pasted together with the optical fiber. Fiber optic has four waterproof gates, namely, plastic sheath, metal sheath, water-proof layer and ointment. Then the question arises. Why are optical fibers so afraid of water? Why aren't the aquarium glass and window glass at home afraid of water while they are waterproof? Why are they all glass so different?

It is generally believed that optical fibers are not afraid of water, because glass has excellent water absorption. It is generally believed that optical fibers are not afraid of water, because glass has excellent water absorption. But in fact, water is very harmful to cables. If water enters the fiber optic cable, it will damage the optical fiber if it freezes and expands in the cold water, so the cable needs to be filled with ointment to prevent moisture from entering.

The reason why optical fibers are afraid of water is that optical fibers are made up of glass (Si04) tetrahedrons connected with each other. In a Si-O-Si network, oxygen atoms exist in the form of bridge oxygen. However, in the environment with water, after the glass surface adsorbs water and gas, the hydrolysis reaction slowly occurs, which leads to the breakage of the silicon-oxygen bond in the original network-Si-10-Si-1 and the transformation of bridge oxygen into non-bridge oxygen. As a result, the glass cracks are caused, which are growing continuously. 

Whether for fish tank glass, window glass or optical fiber glass, they are afraid of water. The difference is that fish tank glass, window glass are very thick, with the thickness of 3mm, 5mm, l0mm, even if there are 0.05mm cracks do not affect the strength of the glass, and naked eyes can not see changes. Fiber optic glass is different. The diameter of fiber optic glass is only 0.125 mm, which is as thin as hair. If there is an 0.05 mm crack, the diameter of fiber optic will remain 0.075 mm. Therefore, fiber optic is very easy to break. In addition, the appearance of OH root will increase the absorption loss of fiber to light. This is why aquarium glass and window glass are not afraid of water while optical fiber glass is afraid of water.

Even so, the cable is damaged, and the joint box is not sealed properly, and the exposure of bare fibers will lead to shorter service life and natural fiber breakage due to water.

Shenzhen Yutai Optoelectronic Communications Co., Ltd. provides high quality optical cables, which is the best choice for buying fiber optic cable.

In the network hardware, there is another kind of network transmission media that can not be ignored. We usually call it the network line. At present, the common network cables are thin twisted pair, fiber optic cable, coaxial cable and thick coaxial cable.

Fiber optic cable is a new generation of transmission media.

Compared with copper media, the security, reliability and network performance of fiber cable have been greatly improved. In addition, the bandwidth of optical fiber transmission is much larger than that of copper cable, and the maximum connection distance supported by optical fiber transmission is more than two kilometers, which is the inevitable choice to build a large-scale network. Fiber optic cable has many advantages, such as good anti-electromagnetic interference, strong confidentiality, fast speed and large transmission capacity, so its price is more expensive, and it is seldom used in home occasions.

At present, there are two kinds of fibers--single-mode fibers and multi-mode fibers (so-called "mode" refers to a beam of light entering the fibers at a certain angle). Multi-mode optical fibers are generally used for network connections in the same office building or relatively close areas. Single-mode optical fibers transfer data with higher quality and longer transmission distance, which are usually used to connect office buildings or geographically dispersed networks. If the optical fiber cable is used as the transmission medium of the network, the optical transceiver and other devices need to be added, so the cost is higher, and it is seldom used in general applications.

Twisted pair cable is a flexible communication cable, which contains pairs of insulated copper wires. It is characterized by low price, so it is widely used, such as our common telephone lines. According to the different maximum transmission rates, twisted pairs can be divided into three categories, five categories and super five categories. Three types of twisted pairs have a speed of 10 mb/s, five types can reach 100 mb/s, and the super-five types can reach 155 mb/s, which can meet the needs of multimedia data transmission in the future. Therefore, five or even super-five types of twisted pairs are recommended.

Twisted pair can also be divided into shielded twisted pair (stp) and unshielded twisted pair (utp). STP twisted pair has a lower speed (only 4mb/s), but its anti-interference ability is stronger than UTP twisted pair, so its price is much higher. Now this cheaper kind of twisted pair is a few yuan a meter, while it may be tens of yuan for the expensive ones. In contrast, the price of UTP twisted pair is generally about one yuan per meter, which is relatively low.

In addition, the popular terms of 10m and 100m unshielded twisted pairs are called 10Base-T and 100base-t, which are often seen on the market. RJ45 crystal head is also used to make the connection between twisted pair and network card RJ45 interface. Its quality is directly related to the stability of the whole network, which can not be ignored.

Coaxial cable is a kind of transmission medium which is familiar to many friends. It is a layer of insulated wire wrapped around the central copper conductor cable. Its greatest feature is good anti-interference ability, stable transmission data, and cheap, so it was once widely used, such as closed-circuit television lines. However, coaxial cables have been widely used in the past, mainly because the bus network structure composed of coaxial cables has low cost, but the damage of a single cable may lead to the paralysis of the whole network and difficult maintenance, which is its biggest drawback.

Optical cable handover box is a kind of handover equipment which provides end-to-end and jump-over for main layer and distribution layer optical cables. After the cable is introduced into the cable junction box, the main layer cable and the distribution layer cable are connected by jumping fibers after being fixed, terminated and distributed.

The thing placed inside is the end of the optical cable, and the function of the end of the optical cable is to gather two or more signals of the original unrelated computer room together, and then use tail fiber to connect two unrelated cables according to need. Its signal source is the computer room.

Optical intersection boxes collect all optical signals. Optical signals can not be used directly. Photoelectric conversion equipment is needed to convert optical signals into electrical signals. Therefore, if you want to use the signals in optical intersection boxes directly, it is very expensive.

Similar to the optical cabinet, there are also electrical cabinets. The appearance of the electrical cabinet is not different from that of the optical cabinet. However, the signals collected in the electrical cabinet are electrical signals, which can be directly used without conversion. The signal source of the electrical cabinet is also the computer room.

Fiber optic cable junction box is a kind of outdoor connection equipment. The most fundamental requirement for it is to be able to withstand dramatic changes in climate and harsh working environment. It should have the characteristics of waterproof gas condensation, waterproof and dust-proof, pest and rodent prevention, and strong impact damage resistance. It must be able to withstand the harsher external environment. Therefore, waterproof, moisture-proof, dust-proof, impact-proof, pest and rodent-proof requirements are relatively high on the outside of the box; temperature and humidity control requirements are very high on the inside of the box. According to international standards, the highest standard for these projects is IP66. But there are not many cases that can meet this standard.

At present, the main cabinets used in China are KRONE cabinet in Germany, which is made of unsaturated polyester glass fiber reinforced material (SMC) and has good performance in waterproof, moisture-proof and impact-proof. The imitation of domestic reference KRONE boxes is mainly iron metal boxes (generally up to IP65 standard). For metal box, because of its poor performance in waterproof gas condensation, it is doomed not to be widely used and gradually eliminated. Some domestic imitations are quite different from KRONE imported from Germany in terms of waterproof gas condensation and shock resistance due to material performance problems. In addition, due to the poor anti-aging performance of sealant strip, the performance of waterproof and dust-proof is also common. Of course, it is acceptable to reduce performance requirements and investment when the external environment of the installation location of the cable junction box is better.

Shenzhen Yutai Photoelectric Communication Co., Ltd. is a professional fiber optic cable supplier, providing high-quality optical cables. Welcome to buy.

According to the physical and electrical properties of optical cables, the laying of optical cables must meet certain requirements. In addition, the laying of optical cables in different environments also have their own requirements.

The laying of optical cables shall strictly comply with the following requirements:

(1) Length and integrity: The length of each cable should be controlled within 800m, and there is no relay in the middle.

(2) Minimum installation bending radius of optical cable: under static load, the minimum bending radius of optical cable is 10 times than the diameter of optical cable; under load conditions during wiring operation, such as pulling the optical cable out of the pipe, the minimum bending radius is 20 times than the diameter of optical cable; the minimum installation bending radius of four-core optical cable must be greater than 2in (5.08 cm). 

(3) Installation stress: The maximum installation stress applied to 4/6 core cable shall not exceed 100lbf (45kgf); when multiple 4/6 core cables are installed at the same time, the maximum installation stress per cable shall be reduced by 20%. For example, for 4x4 core cable, the maximum installation stress shall be 320lbf (144kgf).

Explanation: It is required that the traction force of the cable should not exceed 80% of the allowable tension of the cable, and the maximum instantaneous traction force should not exceed the allowable tension of the cable. The main traction force should be applied to the strengthened components of the cable, and the fiber can not bear the tension directly.

(4) Installation pulling force of optical fiber jumper: the maximum pulling force of single-core soft wire is 27 LBF (12.15 kgf), and the maximum pulling force of double-core soft wire is 550 LBF (22.5 kgf), and the distance of interconnection equipment should not exceed 100 ft (30 m).

(5) Judging the A.B end of optical cable: Before construction, we must first judge and determine the A.B end of optical cable. A-terminal should be oriented towards network hub
direction, while the B-terminal should be oriented to the user's side. The end of the laying cable should be in the same direction, and it must not be mistaken.

(6) No matter laying optical cables in buildings or between buildings, separate pipe holes should be occupied. If the original pipe and copper cable are used together, the plastic sub-pipe should be put through the hole. The inner diameter of the plastic sub-pipe should be 1.5 times than the outer diameter of the optical cable. The optical cable should be laid in the plastic sub-pipe, and the same sub-pipe should not be used with the copper cable. When laying optical cables are in parallel with other weak current systems in buildings, they should be laid separately and fixed, and the minimum net distance between the cables should meet the design requirements.

Shenzhen Yutai Photoelectric Communication Co., Ltd. is a professional fiber optic cable supplier, providing high-quality optical cables. Welcome to buy.