Commonly used outdoor optical cables are divided into two structures: central bundle type and layered optical cable:
① Central tube type optical cable: The center of the optical cable is a loose tube, and the strengthening member is located around the loose tube.
ZR Cable outdoor optical cable
GYXTW cable:
Bundle tube: The material of the bundle tube is PBT, which is hard and flexible and resistant to lateral pressure. Some small factories use PP instead of PBT, and the cost can be reduced by half, but the optical fiber inside is easy to break during transportation and construction. The color of PP is translucent.
Colored optical fiber: In order to distinguish each core optical fiber in the communication engineering, the bare fiber is extruded with a layer of colored plastic. The outdoor optical cable is to dye each core bare fiber with different colors of ink. The color of the ink is the same as that of the indoor cable. There are also 12 kinds. The color spectrum of the industry standard of the Ministry of Information Industry is arranged as follows: blue, orange, green, brown, gray, white), red, black, yellow, purple, pink, turquoise. The use of natural colors in place of white is permitted without affecting identification.
Color-locked optical fiber: In order to protect the optical fiber, a layer of 250-micron translucent resin is coated on the surface, and the optical fiber needs to be colored with different colors for each core fiber when it is made into an optical fiber cable. Therefore, some foreign optical fiber manufacturers cover the optical fiber during production. There are 12 different colors of resin on it, so that the fiber optic cable factory does not need to recolor it when it is used. The advantage of this is to save a coloring process, but the disadvantage is that it cannot be used flexibly.
Water-blocking tape: The water-blocking tape is made of water-blocking powder added between two layers of non-woven fabrics. Once the optical cable enters the water, the powder rapidly expands dozens of times after absorbing water, producing a gel like jelly to block the water from going deeper into the optical cable. spread everywhere.
Non-woven fabric: Some manufacturers will replace the water-blocking tape with a non-woven fabric with a much lower cost than the water-blocking tape to reduce the cost. There is no difference in appearance. Once the outer skin of the optical cable is broken, the non-woven fabric cannot block water.
Corrugated steel strip: The water blocking strip is covered with a corrugated steel strip. The main function of the steel strip in the optical cable is to resist lateral pressure, tensile, anti-rat bite, and protect the bundle.
Steel wire: We see two parallel steel wires outside the steel strip. The function of the steel wire is to enhance the tensile force of the optical cable. The gray steel wire is phosphatized, and the silver surface is galvanized to prevent the steel wire from rusting. Galvanized steel wire is more expensive than phosphating steel wire.
Optical cable sheath: Outdoor optical cables generally use medium density polyethylene (MDPE), and some customers specify high density polyethylene (HDPE). The cost of using high-density PE is slightly higher. There are also orders specifying low smoke zero halogen material (LSZH) for the jacket. Many manufacturers also use recycled materials as fiber optic cable jackets to reduce costs. The fiber optic cable made of this material has a rough skin, contains a lot of impurities, and is prone to cracking and water seepage. The source of recycled materials is to smash some wire and cable sheaths, plastic bottles, slippers, etc., and re-granulate them after returning to the furnace.
Because there are only 12 colors of optical fibers, the national standard (also international standard) central bundled tube optical cable can only achieve 12 cores at most. There are also some non-standard central bundle tube optical cables with more than 12 cores, but generally no more than 24 cores. The method is to choose one of the two optical fibers of the same color and use the inkjet printer to spray a bar at a certain distance to distinguish them. Optical cables with more than 12 cores are generally stranded.
Small central bundled fiber optic cable JET
This kind of structure is used a lot abroad, adding glass fiber yarn (or aramid, high-strength yarn) to the bundle tube with optical fiber and then extruding the sheath. The optical cable is relatively soft and has a certain tensile force, which is suitable for indoor and outdoor use. Overhead, wearing pipes are relatively aspects.
② Layer-stranded optical cable: Multiple bundles of optical fibers are stranded on the central core strength member in a twisted manner. Such optical cables, such as GYTS, GYTA, etc., can obtain larger cores by combining loose tubes. number of fiber optic cables. The color separation of the stranded loose tube is usually separated by the red and green color spectrum, which is used to distinguish different loose tubes and different optical fibers. The number of cores of the stranded optical cable can be larger, and it can be produced by optical fiber ribbons, which can achieve more than one thousand cores.
Optical cables with 60 cores and below often use a 5-tube structure. For example, 60-core optical cables use 5 bundled tubes, and each bundled tube contains 12 optical fibers. Generally, the stranded optical cable with less than 12 cores is twisted together with a bundle tube containing 12 optical fibers and 4 solid filler ropes. It can also be twisted with 2 6-core bundles and 3 filling ropes, or can be matched in other ways.
GYTS type optical cable: In the layer stranded optical cable red, this type and GYTA are the most common. Several bundles of tubes are twisted on a thicker phosphating steel wire, the gap of the twisted cable is filled with water-blocking cable paste, and there is a circle of plastic-coated steel tape on the outside, and then the sheath is squeezed.
GYTA type optical cable: The structure of this optical cable is the same as that of GYTS, except that the steel tape is replaced with an aluminum tape. The lateral pressure resistance index of the aluminum belt is not as high as that of the steel belt, but the rust and moisture barrier performance of the aluminum belt is better than that of the steel belt. In some environments where GYTA is used, the optical cable has a longer service life.
GYFTY type optical cable: This type of optical cable is to twist several bundles on a non-metallic reinforcing core, fill the twisted gap with cable paste or protect a circle of water blocking tape, and directly squeeze the sheath without armoring.
This model has various evolutions. It is used in some overhead environments. In order to increase the tensile force of the optical cable, some aramid fibers should be added to the stranded cable core and then extruded. If the central reinforcement is made of steel wire instead of a non-metallic reinforcement core (FRP), the model is GYTY without F (for non-metallic).
FRP reinforced core: This material is generally made of glass fiber, and the strength of the outer diameter is also greater than the tensile force of the steel wire. When training the optical fiber, we know that the optical fiber is made of high-purity glass and is not afraid of lightning, but the optical cable is in an outdoor overhead environment, and the metal parts in the middle are easily damaged by lightning. Seeing the model with F, we should know that it is mainly lightning protection. The cost of FRP reinforcement is slightly higher than that of steel wire reinforcement.
Type 53 optical cable: We see some models such as GYTA53, GYTY53, this model is a layer of steel armor and sheath outside the GYTA, GYTY optical cable. It is used in those occasions where the environment is relatively harsh. When you see 53, you should know that it is an extra layer of armor and an extra layer of sheath.
Physical drawing and cross-sectional drawing of GYTA53 model:
Figure 8 optical cable: This optical cable is used more in some sparsely populated countries. A sling is added outside the bundled or layered optical cable. The sling is generally stranded with 7 steel wires with a diameter of 1.0 mm. , or 1 galvanized steel wire with a diameter of 2.5 mm.
Tubular 8 figure cable GYXTC8S:
Layered steel armor GYTC8S, layered aluminum armor GYTC8A
Fiber-to-the-home cable: This cable requires a small outer diameter and low cost, and is suitable for pipe or cable ducts.
FTTH cable:
This kind of optical cable is generally sheathed with LSZH, strengthened by two FRP, and two cores of G657 fiber in the middle. The outer diameter is very small, and the optical fiber can be exposed directly by tearing without professional cable opening tools.
Ordinary home optical cable GYXTPY:
The structure of this optical cable is: after adding two parallel steel wires to the bundle tube, the sheath is directly extruded, no steel armor is required, the outer diameter is small, and the cost is low. Used in fiber-to-the-home projects. Some economically underdeveloped countries also like to have this kind of optical fiber cable because the price is cheap.
ADSS fiber optic cable: This kind of fiber optic cable is to add aramid fiber to the outside of the GYFTY fiber optic cable and then squeeze a layer of sheath.
This kind of self-supporting optical cable is used on outdoor high-voltage poles. In addition to knowing the number of cores of the optical cable, several indicators must be known to calculate the cost.
Span: that is, the distance between each pole. In a communication project, if the distance between the designed poles is farther, the amount of poles will be reduced, but the optical cable needs to be strengthened by its own pulling force in the air, and the amount of aramid in the optical cable will be reduced. The larger it will be, the cost of the fiber optic cable will increase accordingly.
Wind speed: The greater the wind in the use environment, the greater the amount of aramid in the optical cable, and the higher the cost.
Ice ice: In severe cold areas, ice formation will form on the outer skin of the optical cable after it is exposed to rain, which increases the pulling force of the optical cable in the air, and also increases the amount of aramid fiber, and the cost increases accordingly. This factor does not need to be considered for use in non-cold areas.
The above three indicators are based on the use environment to calculate the amount of aramid fiber in the optical cable. As we mentioned earlier, aramid fiber is a kind of high-cost reinforcing fiber.
Arc resistance: ADSS optical cables are all used on high-voltage utility poles, and arcs from high-voltage wires will burn the cable sheath, so ADSS optical cables are generally sheathed with arc-resistant materials. Usually the arc is 110KV (kilovolt) and 220KV. The effect of conventional arc-resistant materials in 220KV environment is not very good, and OPGW optical cable is generally used instead.
OPGW optical cable: This optical cable is to install the optical fiber in an aluminum tube, and then twist multiple aluminum tubes and steel wires to form an all-metal structure, which is grounded at both ends to protect against lightning.
