This post was authored by Loredana (Coscotin) Negriu, product manager at Technetrix, and formerly product manager with Belden.

 The once simple Ethernet cable has evolved into the foundation of modern Internet and global connectivity. Ethernet networking has gained momentum and popularity, penetrating lots of industrial applications, such as manufacturing, power utilities, oil and gas, and transportation. This includes energy-exhaustive machines, such as motor control centers, robots, mobile machines, and heavy equipment. Cabling in these environments can be difficult to install, requiring extra protection and resilience.

Proper cable installation is critical to maintaining uptime. Network components and media are the cause of more than 70 percent of all network faults, with operating systems accounting for less than 20 percent and application programs for the rest. The costs of the components are minimal compared to that of a network failure, where downtime costs can be measured in thousands of dollars per minute.

One recent example of network failure should help add perspective. When the installation of a fire protection system, including cabling, for a large power generation plant did not work, heads turned to the contractor upon network examination. The contractor had installed 2.485 miles of speaker wire instead of the industrial Ethernet twisted-pair cable specified by the engineers. Their reasoning, “It looked the same as the other wire!” Inevitably, the contractor paid the final price by having to go back, pull out the wire, replace it, and pay for the replacement expenses.

The bottom line? Network designers and engineers need to concentrate on building the hardware foundation for the entire network infrastructure.

Figure 1. The Open Systems Interconnection model shows the layers of communication systems and where network failures occur. Network components and media account for more than 70 percent of failures.

 

Communication. Communication. Communication.

Those designing communications infrastructure should pay attention to switches, cables, and connectors. Although each is critical in its own right, users of these components need to evaluate the entire network communication system to recognize where failures are most likely to occur, as well as the costs of these failures in downtime, repairs, and replacements.

Communications and control networks are expected to operate consistently and reliably in all types of environments. But, in mission-critical applications and extreme environments, industrial networked communications systems should be extremely rugged and robust. Any physical deterioration or electrical failure in key data transmission components can lead to defective network performance and safety issues, ultimately leading to loss of critical data, costly downtime, or even catastrophic failure.

Before selecting an industrial Ethernet cable, it is important to understand your network’s environment. Each industrial facility is different—one size does not fit all.

Industrial applications require industrial cable

In a typical office setting, the Ethernet infrastructure is installed in a relatively clean, quiet environment with cables hidden behind walls, in ceilings, and under floors, while network switches, hardware, and connectivity components are sheltered in protected areas. Industrial facilities present a very different reality.

Most cables, connectors, switches, and active network components are integral to machine automation, instrumentation, and industrial control systems—so they may need to be in harsh and potentially hazardous situations. Even the best commercial-off-the-shelf Ethernet systems are not made to handle such conditions over time. Rigorous conditions call for ruggedized cables—only industrial-grade Ethernet system components are tough enough to withstand the hazards and risks they are exposed to daily.

To connect the individual components of an industrial network—from the cabinet, through the telecommunications room to the factory floor, to the actual machine—companies need to select an industrial Ethernet cable and connectivity solution that ensures the highest level of reliability, quality, and performance. Products need to be suitable for high-abrasion locations facing direct contact with oil and solvents, taking account of electromagnetic interference (EMI), high operating temperatures, ambient temperatures, power/voltage fluctuations, machine vibration, mechanical hazards, and more.

Process orientation: Selecting the right industrial Ethernet cable

To guide you to the most suitable technology for your network, here are five steps for selecting the right cable.

Step 1: Identify the application

The first step is to understand the type of application where the cable will be used. You should be able to identify the application by choosing an environment below:

  • Cabinet/control room and permanent installation: This includes enclosed environments, where vibration is limited. In these applications, a solid conductor is the right choice, future-proofed with high bandwidth competency.
  • Factory floor and moderate flexing: For the factory floor and work areas where there are raised levels of vibration, and cables are likely to be exposed to oil, chemicals, rough handling, abrasion, ultraviolet radiation, temperature variations, and electronic noise (EMI and radio-frequency interference).
  • Continuous flexing (high flex): For use on the machine itself, where vibration and temperatures are high to very high, and the need is for highly flexible cabling resistant to trailing and torsion, as well as a high level of connectivity protection against liquids (M12 with IP67 and IP68 protection).

 

Step 2: Agree on data rate requirements

Use the table below to determine the correct cable for the data transmission rates you need.

Table 1. Different types of cable are needed to achieve different data transmission rates.

 

Step 3:  Pick the type of jacketing

Choosing the right jacket material for your cable guarantees the best performance. Figure 2 outlines the various types of available jackets and their respective attributes.

 

Step 4: Know the difference between shielded and unshielded cables

There are two types of cables you should be aware of: shielded cables and unshielded cables. Shielded cables are recommended for especially high-noise environments, while unshielded cables can be used in most environments.

A shielded cable typically has a foil or braid to protect the reliability of the signal and to screen out interference and noise. For extra durability and noise protection, a foil/braid combination should be used.

Step 5: Choose a type of conductor

The first aspect is solid versus stranded conductors, and the considerations and options for this choice were given in step 1. The second aspect is twisted-pair versus bonded-pair construction. Bonded-pair cables offer resistance to the rigors of installation with a manufacturing system that affixes the insulation of the cable pairs along their longitudinal axes, so no gaps can grow between the conductor pairs. Nonbonded-pair cable construction can be susceptible to pair gapping during installation and to impedance mismatches.

Twisted-pair cable construction can be susceptible to pair-gapping during installation as well as impedance mismatches. Choose between twisted pair or bonded pair, available in solid and stranded conductors. The solid/stranded conductor discussion should be incorporated within the first step (choice of application), as the application is directly linked to the type of conductor (cabinet=solid, moderate flex=stranded, continuous flex=highly stranded/trailing/torsion).

Figure 3. Twisted-pair conductors have gaps that decrease performance.

 

The right cable protects core network infrastructure from failure

Up until now, plant engineers have developed creative, but not always dependable or suitable ways of routing cable through a plant network. This might mean putting Ethernet cables through conduits or through separate trays, or attaching them to water pipes with ties or tape. These make-do solutions both add to the cost of installation and downtime and increase the likelihood of signal transmission failure.

Once you have specified the right industrial Ethernet cable, ensure it is the one that is actually installed. Doing this ensures your mission-critical operation is properly equipped for maximum dependability and performance. Your cables should be sufficiently hardened, have high electrical performance, and be shielded against electrical noise. When the cable has the right certifications for all of the network and its industrial applications, then your network will run successfully—diminishing any downtime or costly repairs.

The bottom line is that selecting the right cable can make the difference between success and failure of any network communications infrastructure and its systems. If you choose the wrong cable, you will never get the network to work effectively, which can easily lead to expensive network failures, downtime, and expensive replacement of installed cable.

About the Author
Loredana (Coscotin) Negriu is product manager at Technetrix, and formerly was a product manager with Belden. At Belden she was is responsible for all vertical marketing related to Belden’s portfolio of industrial cables, including the company’s DataTuff range. With a master’s degree in strategic marketing from the University of Maastricht, She also held various positions in Belden’s marketing department, most recently as product manager for fire alarm and circuit integrity cables, where she gained an in-depth understanding of data transfer in mission-critical applications.

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A version of this article also was published at InTech magazine

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