It sounds like it should be easy for any IT manager. Moving your otscable network setup from an office environment into the factory floor should just be a matter of simple logistics, right? Get extra cables and hardware, update the connectors, and you should be good to go, right? Yet, it isn’t. There are many challenges and additional requirements that need meeting if you plan to install a network and ethernet cables in an industrial location.
The fact is that the typical office is a lot safer for ethernet cables than a factory would be. There is all manner of factors and details to consider, setting the two apart. There are also nuances in the needs of office versus factory, which will determine things like hardware choices and requirements for performance. Let’s take a look at these.
Industrial environments have features and risks that offices and homes do not.
You have harsh conditions, such as extreme heat or cold. You have hazards like gas, oil, and all manner of chemicals which can cause problems. The machinery might cause damage to the cords as well, not to mention potentially rip the typical ethernet connector right out of the port by accident. Humidity, moisture, corrosion, vibration, and even electromagnetic fields can be troubling in an industrial site.
The nature of what a factory needs can also make the transition different. An office can manage with a connection that’s slightly slower because in most cases real-time monitoring and data gathering isn’t important. On the other hand, on the factory floor, getting that information in real-time can be a huge factor in operations. Resiliency is also crucial since an office can weather the loss of network connectivity better than an industrial site can.
Manufacturers, in an effort to meet industrial demands, might offer cables specifically meant for those areas. In many cases, this will mean an extra jacket that protects against the environments that are typical on a factory floor. These will have properties that make them more rugged and resilient, but also make them more expensive. However, there are limits to this, particularly when it comes to extremes of temperature.
What is the Standard?
The standard Ethernet cable uses twisted pairs of copper wire, usually between two to four of them. These will have a metal that surrounds them as protection. On top of that metallic shielding will be a jacket. Cat-5 cables don’t have anything that reduces the risk of crosstalk, though Cat-6 and higher will include these as part of the standard.
Ethernet cables use a specific type of copper for their wires. This is oxygen-free high conductivity (OFHC), which has a required 99.95% minimum copper content. The size of the conductor and stranding will have an effect on its ability to resist DC, the loss of signal strength due to insertion, and other performance aspects tied to electrical current. Some cables might use bare copper, while others use a variant known as tinned copper.
There are limitations here, of course. The typical jacket isn’t meant to withstand extremes of temperature. They aren’t built to take the rigors of physical damage in the form of abrasion, pressure, cutting, and tearing that may occur in an industrial setting. Connectors are also more vulnerable to damage for most cables. Finally, the shielding simply isn’t adequate to protect against the more intense EM interference machines in a factory might generate.
Variations in Size
The slightest variation in the size of a cable’s conductor can have a drastic effect. They can cause increased insertion loss, as well as make the cable heavier and less flexible. As such, most manufacturers attempt to balance these factors as much as they can.
Another change made to industrial ethernet cables is flame resistance. Extreme heat and fire are hazards in any factory, with the basic jacketing of most ethernet cables liable to melt in the worst of conditions. Depending on the requirements, the jacketing might be made of different materials. However, the most common is fluorinated ethylene propylene and polyolefin.
These two have good dielectric and dissipation factors, which allow the electrical currents in the cable to work despite difficult external conditions. Both are also resistant to fire, allowing the cables to withstand that potential hazard. However, the electrical protections these materials provide will vary based on the frequency. Since higher categories open up new frequencies, so the grade of the protection will shift as you go higher.
While it means something else to the layman, eccentricity is a term that is important in an industrial context. It is a parameter at the extrusion stage and is the main reason for irregularities. They create instability when conductors in a cable are twisted and paired. Whenever possible, manufacturers intending ethernet to be used in a factory setting make an effort to keep the eccentricity within 3%.
The twisting of the pairs is also critical. This is where all of the main electrical characteristics and performance is determined. In other words, when the pairs are twisted, you literally determine how good the cable will be once it’s in use.
The length is one major concern. Each pair’s length affects factors such as skewing of time, the delay in transmission of the signal, and the risk of crosstalk between pairs. In terms of process, the twisting also helps balance insulated conductors and influences the cabling. If you don’t get the twisting right, you exaggerate physical flaws caused during the cabling process.
Signals with different frequencies can travel using the same single twisted pair. This means that certain signals have the same frequency as the intrinsic one, or at least harmonic to it. This causes crosstalk to spike, as the energy is accumulated over time due to the harmonics. The length between twisting can mitigate this.
Cabling can be a simple process that involves bundling four or more pairs in a bunch, following a sequence. It can also become more complicated, adding things like filler for shape, tape to provide isolation, and using stranded tinned wires for draining. No matter what the materials are chosen or the method of implementation, the goal remains to reduce the risk of crosstalk between wires.
When choosing a filler material, the general rule is that it has to perform similarly or better than the insulation. The point of the tape is to keep the drain wire and the shielding separate. It can also function to push the two away from the pairs, preventing them from impairing the electrical current.
Braiding is a method that is often used for industrial-grade cables because it minimizes interference from low-frequency electromagnetic fields. It also provides additional mechanical resilience. Braids can also be used to provide grounding continuity, preventing machine noise from the factory floor.
It is no secret that industrial environments are harsh, and they don’t let up even on ethernet cables. Cables used in such locations must be made of sterner stuff and have more protections. Otherwise, they will fall apart due to the stresses of a factory floor.