How To Choose Stable And Reliable Industrial Cables In Harsh Environments?

In various industrial scenarios, cables are responsible for power transmission tasks. In various energy scenarios, cables are responsible for signal communication tasks. In various outdoor scenarios, cables are exposed to extreme temperatures and harsh conditions for a long time. In various outdoor scenarios, cables are long-term exposed to chemical corrosion and harsh conditions. In various outdoor scenarios, cables are long-term exposed to mechanical shock and harsh conditions. How to ensure stable operation of cables, how to ensure reliable operation of cables, and how to ensure safe operation of cables are the core challenges of engineering design and equipment selection. This is by no means a simple wiring job. It is related to the frontier of materials science, the frontier of protection technology, and the frontier of systems engineering.

How to select cables for harsh environments

To deal with harsh environments, cable selection is the first step, and ordinary indoor standards should never be copied in a simple way. First of all, environmental stress must be accurately assessed. For example, offshore platforms must deal with salt spray corrosion, chemical plants have acid and alkali media, and mining machinery has frequent bending and rolling. Different stresses determine the direction of selection of cable sheaths and insulation materials.

It is necessary to examine the key performance parameters of cables in a targeted manner based on environmental stress analysis. The flame retardant grade is a hard indicator, and the temperature range, such as -40°C to 125°C, is also a hard indicator. Oil resistance is a hard indicator, and acid and alkali resistance is also a hard indicator. For example, in high temperature areas, silicone rubber insulation or Teflon insulation should be used. In places where hydrocarbon fires may exist, fire-resistant cables that comply with the IEC 60331 standard must be used to ensure that the integrity of the circuit is maintained in the event of a fire.

What are the special cable materials?

The fundamental factor that determines the environmental resistance of cables is the material. Common special sheath materials contain polyurethane (PUR), which has excellent wear resistance, oil resistance and hydrolysis resistance, and is very suitable for mobile equipment such as robot drag chain cables. Chlorinated polyethylene (CPE) and cross-linked polyethylene (XLPE) are widely used in outdoor and high-temperature fixed laying due to their excellent weather resistance, heat deformation resistance and electrical stability.

In addition to the sheath, the internal conductor is critical, the insulation is also critical, and the filler is also critical. Tinned copper conductors can effectively resist oxidation, and tinned copper conductors can effectively resist sulfide corrosion. The insulation layer can be made of materials such as ETFE, which is an ethylene-tetrafluoroethylene copolymer. The insulation layer is both flexible and has high chemical resistance. Some high-end cables will use halogen-free and low-smoke materials. Halogen-free and low-smoke materials will not release toxic halogen acid gas when burned. Halogen-free and low-smoke materials can improve personnel escape safety.

How extreme temperatures affect cables

Temperature is the most common factor that affects the life and performance of cables. Low temperature will cause ordinary plastic sheaths and insulation layers to become fragile and brittle, causing cracks to appear when they are bent or vibrated, thereby causing insulation failure. Therefore, cold areas or cold chain equipment must use materials with cold-resistant formulas to ensure that they can still maintain flexibility in low-temperature environments.

High-temperature environments will cause problems related to accelerated aging. Continuous high-temperature conditions will cause the degradation of the molecular chains of insulating materials, resulting in a decrease in insulation resistance and an increase in leakage current, which will eventually cause a short circuit. At the same time, high temperatures may accelerate the oxidation process of metal conductors, causing increased resistance, resulting in power loss and overheating. During the design process, cables with corresponding thermal grades must be selected based on the actual ambient temperature, and the derating factor of their current carrying capacity at high temperatures must be considered.

How to protect against chemical corrosion environment

Corrosive media such as acids, alkalis, and solvents are prevalent in chemical industry, electroplating, sewage treatment and other places. Such media can corrode ordinary cable protective sheaths, causing them to swell, crack or even dissolve, thereby damaging their internal structures. The first principle of protection is to select materials that are compatible with the media, such as polyvinylidene fluoride (PVDF), which has excellent resistance to most strong acids and alkalis.

In addition to the chemical resistance of the material itself, the structural design is very important. Use a seamless extruded sheath to reduce the gaps and gaps that media can penetrate into. For those particularly severe environmental conditions, you can consider adding a stainless steel braided sheath to the outside of the cable or using a full metal armored cable to provide double physical and chemical isolation. Regular inspections to ensure that the sheath is complete and in good condition, and timely cleaning of any adhesive attached to the surface are also effective ways to prolong the life of cables.

How to deal with mechanical stress

Mechanical stress includes many types of extrusion, tension, shearing, and repeated bending. In places such as mines, ports, and automated production lines, cables often bear such stress. To cope with extrusion and impact, it is usually necessary to add a metal armor layer (such as steel tape armor) or use high-strength aramid fiber braiding as a reinforcement layer to protect the internal core wires from being crushed.

For scenarios such as drag chains and robot arms that require frequent reciprocating movements, special highly flexible cables are required. The conductor of this cable adopts a multi-strand finely twisted structure, the insulation and sheath are made of elastomer materials, and the internal core wire twisting and shielding structure are optimized to ensure that there will be no conductor breakage or shielding layer fatigue failure after millions of cyclic bending.

What are the special requirements for installation and maintenance?

When installing in a harsh environment, details play a decisive role in success or failure. The laying path should be as far away as possible from areas with high-temperature heat sources, areas with sharp edges, and areas where chemical media are directly sprayed. When fixing, use corrosion-resistant clamps or corrosion-resistant ties, and be careful that the bending radius cannot be less than the minimum allowed by the cable, otherwise the internal structure will be damaged.

To carry out maintenance work, it is necessary to establish a regular inspection system and pay close attention to the cable sheath to see if it is cracked, hardened, swollen or worn. Pay attention to the connectors to see if there are signs of seal failure, water intrusion or corrosion. Once any suspected damage is discovered, it should be dealt with promptly, because even a small damage can quickly expand in a harsh environment, causing the entire system to malfunction. Maintenance records can help analyze the failure modes of cables and provide corresponding basis for future selection and optimization.

In your field of work or during project implementation, have there been any inappropriate cable selection or maintenance measures that resulted in unexpected shutdowns or failures in harsh environmental conditions? You are sincerely welcome to share your experiences and lessons learned in the comment area. If this article has inspired you, please also feel free to like and share it.