Hello everyone!
Today, I will continue to explain underground optical cable installation. In this article, I will explain pipes and cables for underground installation. Let’s get started.
The pipes that we need to lay in the trench come coiled (typically about 500 m in the coil). The pipes should be carefully unwound and inserted into the trench. If the pipes are not long enough, the pipes can be joined on the floor of the trench using special pipe couplings.
The pipes for underground optical cable installation can be made of PVC or HDPE, with internal grooves for low friction. These internal grooves are very important and suitable for air–brown optical cables.
Figure
1. HDPE or PVC pipes
All cables must pass control while still on the drums (before installation). First, the cable is checked on the drum when it arrives. We check the type of optical cable, fiber standard, cable length, etc. And of course, whether the length of the cable has been agreed and whether there is any damage.
Drums must be stored in a safe and dry place. Drums should not be outside.
During visual inspection, we check cable damage. Based on that, we accept or reject cable reception. After that, this check determines further testing of the optical cable. If there is no visible damage to the optical cable, the fibers to be tested are selected at random - for example, one fiber from each PVC tube (for example loose tube cables). If there is damage to the optical cable, all fibers must be tested.
Cable testing is performed using VFL and/or OTDR. Using a VFL instrument, we check the continuity of the fibers. Using the OTDR instrument, we check the total length, attenuation, macro bending, possible breaks, etc. All measurements should be recorded and taken to the project manager.
The optical cable is on the drum. Care should be taken when unwinding to prevent twisting the cable. The drum is placed on a special stand for unwinding. Based on the manufacturer's recommendation, optical cables can be retracted with special mechanical elements, rarely for a cable jacket.
Figure 2. Non-armored loose tube fiber optic cable
It is often the case that we need to unwind a certain length of cable. We must not allow the fiber optical cable to become entangled. Therefore, figures-8 are formed on the ground and thus prevent the twisting of the cable.
For laying in the pipe, loose tube optical cables without metal elements are used. Cables should prevent the ingress of water and moisture, as do all other optical cables. In addition, the cables should be round, small in diameter, and light in weight. In this way, we can easily pull optical cable in the pipe or use air-assisted optical cable installation.
I will continue to explain this theme in the next article>> Underground optical cable installation (4).
Thank you!
