1. What is the warranty period and service life of an optical cable? What are the documents?
All cable supplied by us is designed for a service life of 25 years. Therefore, cable designs are calculated so that mechanical and climatic loads during installation and operation do not lead to deformation of optical fiber above the specified limits. The warranty period of cable operation is 3 years from the date of cable shipment to the consumer. However, even after the warranty period expires, we maintain feedback with the cable consumer. It is very important for evaluation of cable application practice, improvement of designs taking into account the wishes of installers and operating organizations. The quality of our cable is confirmed by the certificate of conformity GOST 52266-2008. Fire certificates are also provided when ordering non-flammable cable. Each cable construction length is accompanied by the passport, which specifies: cable brand, registration number of technical conditions and declaration of conformity, cable construction length, gross weight, cable drum type, technical and operational characteristics, type and color of optical fibers, refraction indices and attenuation coefficients. The passport is signed by the quality department inspector, who performed the measurements. At the request of the customer other data can be included in the passport.
2. How are cable products transported?
When transporting, drums should not lie on the cheek, this is necessary to prevent damage to the cable products. When transporting, drums must be secured with lashing straps or heels padded to the floor of transport to ensure that the container is securely fastened. When securing drums, nails and staples may not be used to pierce the cheek boards and sheathing of the drum. When rolling the drums, the direction of rotation indicated by the arrow should be observed.
3. What is the difference between aramid filaments and glass filaments in self-supporting cables?
Due to their physical properties, aramid strands as reinforcing elements for self-supporting cable are the best solution in terms of cable quality. They are the lightest and strongest possible and resist perfectly not only tensile but also bending, including vibration loads. If we compare two filaments with the same modulus of elasticity - fiberglass and aramid, the aramid filament is 3 times lighter, 2 times smaller in size, but 5 times more expensive. Hence the main disadvantage of aramid threads is their cost. Modern fiberglass filaments resist tensile loads well, but on large spans the influence of wind loads becomes noticeable, leading to cable vibration. Under the influence of constant bends glass roving can gradually degrade. On the basis of these properties, it is a common practice that self-supported cables up to 15 kN are more often ordered with strengthening elements of glass fibres (without intermediate sheathing up to 10 kN) as they are much cheaper, but also allow to provide the declared service life of the cable. Above 15 kN a cable with reinforcing elements made exclusively of aramid threads is used.
4. Can I weld optical fibers from Integra Cable with fibers from other manufacturers?
When welding fibers from different manufacturers, but complying with one recommendation of the International Telecommunication Union, for example, G.652D, local attenuation in the place of the weld may occur. On the trace it looks like a downward or upward step. The maximum size of the local attenuation is defined by the normative documents as 0.05 dB for 100% connection and 0.1 dB for 50% connections (State Committee of Communications of the Russian Federation Order No 97 of 17.12.97). However, exactly the same step can appear in the welding of fibers of the same manufacturer. The reason for the local attenuation at the welding lies in the difference of mode-spots. This difference within the specified limits exists not only for fibers of different manufacturers, but also for fibers of the same manufacturer of different batches. That is, all fibers present in the market today, corresponding to the same recommendation of the International Telecommunication Union, are welded with each other, provided quality welding equipment is used and the welding procedure is followed. Fibers with reduced bending loss G.652A1 and G.652A2 have a slightly smaller mode-spot size, but are also fully compatible and weldable with ITU-T recommendation G.652D fibers. Exceeding the standard of welding losses is possible when connecting the fibers G.657B1 and G.657B2 with the fiber G.652D.
5. Have you had any negative feedback on any of your cable products?
Cable quality is a balance of many parameters and characteristics. Most cable parameters cannot be determined without the use of special equipment and testing in specialized laboratories. Or the defects of a cable can appear in the process of operation in the form of increased attenuation or optical fiber breakage. During the existence of our plant there has not been a single claim related to non-compliance of the cable with the declared characteristics. But there were some complaints about the cable. The reasons are as follows:
- complaints from installers about the complexity of cable cutting. For example, for a self-supporting cable to work properly in a spiral clamp, it is necessary to tightly crimp the glass strands to the outer sheath. In this case, the outer layer of threads is glued to the sheath and makes it difficult to cut the cable.
- violation of installation technology. For example, for the convenience of unwinding heavy cable, armored with steel wires, installers lay the drum flat, which is strictly prohibited, and begin to throw the coils of cable over the cheek of the drum. The cable is curled into a spiral - it becomes impossible to lay it.
- The wrong conclusions about the quality of the cable made by the supplier. The supplier is holding two samples of the same cable from different manufacturers. One manufacturer achieves the required maximum fiber elongation at MDRH by using a stretch window, i.e., voids in the cable that contain excess fiber. The second manufacturer uses a greater number of power elements and the cable is less bulky. The manufacturer concludes that the higher quality cable is the one that is larger.
- Unreasonable purchasing requirements. For example, the requirement for bend-resistant fiber, while standard requirements for the minimum bend radius of the cable itself. Rewriting all cable manufacturer-specific parameters into the terms of reference when organizing a purchase.
6. Why are there empty modules in an optical cable?
The optical core of a cable is a twisting of optical modules around a central power element. Such a solution not only ensures the strength of the cable due to the central power element, but also gives some freedom to the optical fibers - the so-called tensile window. When a cable is subjected to a tensile load, it begins to elongate, but the elongation is not immediately transferred to the fibers. First the fibers are straightened in the optical modules, then the fibers begin to shift from the center of the modules to the center of the cable, and only then begin to elongate. Therefore, if a customer buys a cable with fiber capacity lower than the maximum fiber capacity of a particular cable design, in order not to disturb the core design, some modules remain empty or they are replaced by cordel fillers, which are rods of appropriate diameter made of any flexible polymer, for example, polyethylene. The presence of empty modules or cordel fillers does not affect the performance characteristics of the cable in any way. Another reason for the appearance of cordel fillers in the core is the customer's desire to have a certain layout of fibers in the module to ensure the uniformity of installation of the entire line. For example, the customer wants a 6-module design with 24 fibers, but for the convenience of assembly he orders a layout of 8 fibers in a module. Then the construction is not launched with a maximum of 24 fibers (6 modules of 4 fibers), but with a maximum of 48 fibers (6 modules of 8 fibers). But only 3 optical modules will be filled, and the other 3 will be empty, or will be replaced by cordel fillers.
7. Why are colorless modules often found in the production of FOCL, because it creates certain difficulties during installation?
The coloring of fibers and optical modules used by cable manufacturers allows for clear and unambiguous identification of each fiber at both ends of the cable. The coloring of the fibers most often contains 12 colors, plus 12 of the same colors with the application of black ring marks with a certain pitch. The coloring of the modules uses a slightly different system - only 2 modules of the entire strand are colored. For us it is red and green. In the twist, the red module is a counting module, i.e. the first, and the green module is a guide (the second), which determines the direction of module counting. That is, on the circumference of the twist the natural module, following the green one, will be the third, and so on. Technically, it is possible to color each optical module in a separate color, but it leads to a significant increase in the amount of waste and increases the price of the cable. I.e. the colored polymer has to be completely drained when changing to another color. In addition to waste, the labor intensity of the cable increases because of the larger number of transitions. Painting each module can be justified only for orders with large volumes.