Apart from this, copper has approximately twice the tensile strength of aluminium and also copper is more thermally conductive than aluminium of the same size.
- Insulator: Those substances through which electricity cannot flow are called insulators.
Currently, the insulating materials used in cable manufacture are generally divided into PE, PVC, and XLPE.
Polyethylene (PE) is a thermoplastic resin produced through the polymerization of ethylene. This insulation material is non-toxic and completely safe, with great temperature resistance, resistance to most acids and bases, and excellent in electrical insulation qualities. As polyethylene is non-polar it has low loss and good conductivity. As a result, it is widely used as an insulating material for high-voltage lines and cables. This is commonly used in wire or cable insulation, and data line insulation material with a low dielectric constant, it’s appropriate for data and communication lines.
Polyvinyl chloride (PVC) is a polymer formed from the free polymerization of vinyl chloride monomer under specific conditions. It is stable and has resistance to acid, alkali, corrosion, and aging. The most essential feature of the PVC material is that it is flame retardant, making it widely used in commonly used household wiring cables as well as special fire resistance cables.
Cross-linked polyethylene (XLPE) is a refined version of polyethylene. It has been enhanced so that the physical, chemical, and thermal properties can be significantly better than those of polyethylene. As a result, this provides distinct benefits over polyethylene insulated wire and cables, including lightweight, good heat resistance, corrosion resistance, relatively high insulation resistance, etc.
- Cable jacketing: It refers to the protective outer layer of the insulation that surrounds and insulates the inner conductors of the electrical cables. It acts as a crucial barrier, protecting the cable from a variety of external elements that could cause damage or failure. Cables are used in a variety of locations, including outdoor installation, industries, and domestic applications. These settings subject wires to moisture, UV radiation, severe temperatures, and chemicals. A cable jacket works as a shield, preventing moisture, UV damage, and corrosion, hence increasing the cable’s operating life. When working with electrical cables, safety is the most important factor. A damaged cable can cause serious electrical hazards such as short circuits, shock, and fire. Thus, cable jacketing can keep the cable’s structural integrity, lowering the danger of electrical failure and mishaps.
Two widely used cable jacket materials are PVC and TPE.
- Polyvinyl Chloride (PVC): This is a versatile and low-cost cable jacket material. It provides durable electrical wire insulation wraps that are resistant to abrasion, moisture, and chemicals. However, it does not work in low temperatures and flame.
- Thermoplastic Elastomer (TPE): This is an excellent jacketing material as it can withstand low temperatures, UV rays, moisture, flame, and chemicals. They are also recyclable.
Cable Manufacturing
Electrical wires are primarily constructed of copper. This is the best conductor of electricity, but different types of cables employ aluminium or other materials of different qualities depending on the function and type of cable.
Generally available medium voltage cables are manufactured in seven stages: incoming feed, polymer feed, triple extrusion, thickness control, cross-linking, cooling, and collection.
- Incoming feed: An input accumulator provides constant power to the driver input coils providing continuous operation without getting shut down.
- Polymer feed: The Polymer is fed totally through a clean and closed room, which ensures the purity of the materials from the supply package to the machine hooper.
- Triple extrusion: Extrusion is carried out through a triple-layer extrusion head, which allows perfect contact between the semiconductors, insulation, and the complete absence of foreign components between them.
- Thickness control: The thickness of each extruded layer is constantly measured by an X-ray measurement head. This guarantees that the layers have a consistent thickness and perfectly concentric
- Cross-linking: To prevent the risk of water absorption, the insulation, and semiconductors are cross-linked in a nitrogen atmosphere, with nine distinct temperature zones that allow the cross-linking processes to be exactly adjusted to the properties of each material.
- Cooling: In this, the catenary tube’s final section is used for the controlled cooling of previously cross-linked cables. This ensures that the temperature at the tube’s exit and throughout subsequent spooling remains optimal.
- Collection: The insulated cable is collected on two winders with an automatic distributor, using an auxiliary pull track to ensure proper spooling, loop by loop, and without excessive stress.
Impact of Recycling and Disposal of Cables and Wires
Throwing cables and wires into the ground will have several negative impacts on the environment, economics, and health. Over time cables and wires can leach dangerous substances such as heavy metals and their poisonous compounds. These toxins can degrade soil health, impair plant life, and infiltrate the food chain, endangering animals and humans. This can leak into the groundwater or run off into neighbouring bodies of water. This contamination has the potential to impact drinking water sources, aquatic life, and ecosystems. The disposal of cables and wires in landfills contributes to the rising problem of garbage overflow.
Proper disposal and recycling of the cable and wires will provide certain benefits. Recycling will conserve the raw material, reducing the need for extensive mining and extraction processes that harm the ecosystem. It also reduces the risk of pollution by preventing the release of harmful substances into the soil, air, and water. Economically, recycling cables and wires are more effective as recycled materials are cheaper than the extracted materials. Also, the recycling process is far less economical and energy-intensive than the extracting from the ores.
Recycling Process of Cables and Wires
The operating process of cable recycling differs due to the various sizes and types of discarded cables and wires on the market.
If the waste cables and wires of the single type have a larger diameter then simply use a crusher to break the waste cable and wires into little particles, and then process these small particles using an air separator based on the difference gravity of copper and plastic. Finally, copper will be removed from the waste cables and wires. In addition, if the waste cables and wires include plugs, you can use a liner vibrating screen to separate the brass from the copper.
If the waste cables and wires are disorganized and have varied diameters, the working procedure will be slightly complicated. First, it must add a shredder to shred these waste cables and wires into little pieces, followed by a crusher to crush these small pieces into small particles; otherwise, the machine will be damaged. Then use an air separator to separate the copper and plastic. Furthermore, if there are any waste cables or wires with diameters less than 3 mm, it is best to include an electrostatic separator, which separates metal and non-metal based on conductivity. Copper can be extracted from plastic at a rate of 99%.
Furthermore, some recycling machines are equipped with a pulse dust and cyclone dust removal system to collect dust during the whole process, which can prevent the environment from polluting.
Conclusion
In brief, cables and wires serve as the foundation for technological advancements. However, to achieve long-term system sustainability, some of the problems must be addressed, primarily those relating to the production, installation, recycling, and disposal of cables and wires. Promoting research, innovation, and proper user policy can lead to the development of effective solutions for responsible waste management, minimizing environmental impacts, and maximizing resource efficiency.
Concluded
Diptiman Mohanta is a Student at the Dept. of Electrical Engineering of Parala Maharaja Engineering College in Berhampur, Odisha, India.
Dr. Sarat Kumar Sahoo is a Professor at the Dept. of Electrical Engineering of Parala Maharaja Engineering College in Berhampur, Odisha, India.