Since the beginning of its application in the 1970s, te […]
Since the beginning of its application in the 1970s, telecommunications fiber optic cables have now become the backbone of long-distance trunk lines, local telephone trunking, underwater and submarine communications, and local area networks, private networks, and other wireline transmissions, and have begun to evolve into user access networks, from fiber to Roadside (FTTC), fiber-to-the-building (FTTB), etc. develop towards fiber-to-the-home (FTTH). For various applications and environmental conditions, the communication optical cables are laid overhead, buried, pipes, underwater, indoor and other laying methods.
Overhead cable, buried cable, pipe cable, underwater optical cable basic introduction
An overhead cable is an optical cable used to hang on a pole. This laying method can make use of the original overhead pole road, saving construction costs and shortening the construction period. Overhead cable is suspended on poles and is required to adapt to various natural environments. Overhead cable is vulnerable to natural disasters such as typhoon, ice-flood, and flood. It is also vulnerable to external influences and weakened mechanical strength. Therefore, the failure rate of aerial cables is higher than that of direct-buried and pipeline-type optical fiber cables. It is generally used for long-distance secondary or secondary circuits, and is suitable for private network cables or certain local special sections.
There are two methods for laying overhead cables:
1. Hanging wire type: First fasten with a hanging wire on the pole, and then use the hook to suspend the cable on the hanging wire. The load of the cable is carried by the hanging wire.
2. Self-supporting type: using a self-supporting structure of the optical cable, the optical cable is "8" type, the upper part of the self-supporting line, the load of the optical cable is carried by the self-supporting line.
The laying requirements are as follows:
1. When using overhead cables to lay optical cables in flat ground environment, use hooks to hang; mount optical cables on mountains or steep slopes, and lay cables using lashing methods. Optical cable joints should be selected for easy maintenance of the linear bar position, reserved optical cable with a reserved bracket fixed on the pole.
2. The cable poles of overhead poles require U-shaped telescopic bends every 3 to 5 bars, about 15m per 1km.
3, lead overhead (wall) cable with galvanized steel pipe protection, pipe mouth with fire blocking mud.
4. Overhead optical cables should be given optical cable warning signs every 4 blocks, left and right, cross-river, cross-bridge and other special sections.
5. Trigeminal protection tube protection shall be added at the intersection of the air suspension line and the power line, and the extension at each end shall not be less than 1m.
6. The pole rods close to the road should be covered with light emitting rods with a length of 2m.
7. In order to prevent the hanging wire from inducing electric current injury, each pole pull wire requires electrical connection with the hanging wire. The pull wire type ground wire shall be installed at each pull wire position. The suspending wire shall be directly connected with a backing ring and be grounded directly at the terminal.
8. The overhead cable is usually 3m away from the ground. When entering the building, the U-shaped steel protective sleeve on the external wall of the building must be worn, and then it should extend downwards or upwards. The aperture of the cable entrance is generally 5cm.