Optical Cable
Semiconductive products also have certain applications in optical fiber cables, mainly reflected in the following aspects:
Shield electromagnetic interference
– Application scenarios: When optical fiber cables are laid in some places with complex electromagnetic environments (such as near substations, communication base stations, industrial production workshops, etc.), they are prone to be affected by external electromagnetic interference. Although optical fibers themselves transmit optical signals and are not directly affected by electromagnetic interference on the quality of signal transmission, the metal components in optical fiber cables (such as metal reinforcing cores, metal armor layers, etc.) can induce electromagnetic signals, which may generate induced currents and cause damage to the packaging materials, connection components, etc. of the optical fibers, thereby affecting the service life and reliability of the optical fibers.
– Working principle: In the structural design of optical fiber cables, semiconductive materials are used to make the shielding layer. The semiconductive shielding layer can conduct away the induced charges generated by external electromagnetic interference, forming an equipotential body, thereby reducing the impact of electromagnetic induction on the internal structure of the cable. For instance, by wrapping a layer of semiconductive tape around the metal reinforcing core of an optical fiber cable, the semiconductive tape can conduct the induced charges on the reinforcing core to the grounding device, preventing the adverse effects of electric field changes caused by charge accumulation on the optical fiber.
Improve the electric field distribution
– Application scenarios: At the joints and terminals of optical fiber cables, due to the differences in dielectric constants among various materials and structural changes (such as the connection and sealing treatment between optical fibers and other components), electric field concentration is prone to occur. This concentration of the electric field may lead to partial discharge, accelerate the aging of insulating materials, and affect the stability and reliability of optical fiber connections.
– Working principle: The electric field distribution is improved by using semiconductive products (such as semiconductive paste, semiconductive heat shrink tubing, etc.). Semiconductive paste can be applied to the insulating interface of optical fiber connectors to fill the tiny air gaps, reduce the contact resistance at the interface, and make the electric field distribution more uniform. The semiconductive heat shrinkable tube is placed over the insulating part of the optical fiber terminal, which can evenly distribute the electric field to the surrounding space, prevent the local electric field intensity from being too high, and effectively suppress the occurrence of partial discharge.
Moisture-proof and grounding assistance
– Application scenarios: When optical fiber cables are laid underground, used in damp environments or underwater, moisture-proof measures must be taken. At the same time, good grounding is also crucial for ensuring the safe operation of the cables.
– Working principle: Some semiconductive materials have certain water absorption and ionic conductivity. Using such semiconductive products in the outer layer or internal structure of optical fiber cables can absorb a small amount of moisture that seeps into the cable interior, reducing the impact of moisture on the performance of optical fibers. In addition, the conductivity of semiconductive materials helps to achieve reliable grounding of cables, promptly conducting static electricity, induced electricity, etc. that may be generated during the operation of cables into the ground, ensuring the safety of equipment and personnel. For instance, in some underwater optical fiber cables, semiconductive filling paste is used to fill the gaps between the cable cores, which not only serves to prevent moisture but also assists in grounding.