Protecting Ethernet Connections in Industrial Environments
As Industrial Ethernet brings network connections into harsh environments, it’s essential to protect connectivity products from rugged conditions.
The proliferation of digital information, the Internet of Things, and Ethernet into every facet of our lives means that network connections are in more places than ever before, including the factory floor. Industrial Ethernet is replacing many traditional fieldbus applications due to its inherent reliability, higher speeds, lower latency, increased distance, and improved scalability. Protocols like Ether-CAT, PROFINET, EtherNet/IP, and others are increasingly used for human-machine interfaces, programmable logic controllers, and motor controllers in industrial environments.
The widespread expansion of Ethernet means that more network connections than ever reside in harsh environments — whether it’s a factory floor, a locker room, or a mobile hospital unit — where connectivity components have the potential to be exposed to moisture, chemicals, higher temperatures, and other disruptive elements. When designing, specifying, and deploying networks for industrial environments, it is important to understand which features and industry standards offer the best protection for critical network connections and reliably transmit the vast amounts of data that today’s digital world demands.
Standards to Consider
A variety of standards provide application-independent requirements for balanced copper and fiber optic cable systems that support Ethernet-based data communications in harsher environments. The international standard ISO/IEC 24702, the British EN 50173-3 standard, and the US ANSI/TIA-1005 standard all incorporate the MICE method of classifying parameters, which stands for mechanical, ingress, climatic, and electromagnetic.
MICE classification includes three levels of harshness: Level 1 for commercial office environments, Level 2 for light industrial environments, and Level 3 for industrial environments. These key Ethernet standards are guided by specific parameters for a variety of characteristics that can exist in harsh environments, such as crush and impact in the mechanical category, particulate size and immersion in the ingress category, humidity and temperature in the climatic category, and electrostatic discharge and magnetic fields in the electromagnetic category. Measuring these characteristics may require specialized equipment.
The harshness levels for mechanical, ingress, climatic, and electromagnetic characteristics can vary in a single environment. In fact, a single environment typically includes more than one level. For example, a single environment could be a level three for mechanical but only a level one for ingress, climatic, and electromagnetic characteristics (i.e., M3I1C1E1).
A single cabling link can traverse various MICE classifications along its route. Think of a cable that runs from a networking closet to an outlet located in a cafeteria, locker room, or other end location that could be susceptible to moisture. It is therefore critical to determine the MICE levels along the entire cabling route, plan accordingly, and consider the worst-case scenarios and worst-case level parameters, regardless of the other parameters. For example, the ingress value in an environment that is likely to be exposed to liquid from washdowns, such as a locker room or operating room, may be classified as a level three (i.e., M1I3C1E1). However, if the only ruggedized components that meet that required level of ingress protection are M3I3C3E3, they may need to be used regardless of whether that high level of protection is required for all parameters.
The European Committee for Electrotechnical Standardization (CENELEC) enforces a standards-based rating for ingress protection, originally developed by IEC. Sometimes referred to as IP codes, IP ratings classify protection against solids (e.g., dust) and liquids (e.g., water). A common IP rating required in harsh environments is IP66/IP67, which offers total protection against the ingress of both particulate matter and liquid ingress.
For enclosures like cabinets and junction boxes, the National Electric Manufacturer Association (NEMA) uses a standard rating system that also has IP code equivalents. For example, a common NEMA rating for enclosures in harsh environments is NEMA 4X, which provides protection against dust, water, and corrosion.
Selection Criteria to Consider
To select Ethernet cables and connectivity products that meet specific MICE standards, IP ratings, or NEMA ratings, network designers should check product specifications to ensure that they meet the required levels. Designers should also err on the side of following higher standards when it comes to selecting cable and connectivity components for environments that fall somewhere in between, i.e., are harsher than the typical commercial office environment, but not quite industrial.
Some of the most critical characteristics to consider for Ethernet connectivity in harsh environments include:
Chemical Resistant Housings — Many harsh environments are subjected to cleaning solvents or common industrial chemicals, making plugs and outlets with chemical-resistant thermoplastic housings necessary.
Durable Cable Materials — Cable jacket materials such as polyurethane and thermoplastic elastomers can provide better tensile strength and lower temperature flexibility, as well as better tear, abrasion, chemical, and moisture resistance. Shielding within cables also provides much higher resistance to EMI/RFI, which is ideal for noisy areas.
Ingress Protection — Unused outlets should include caps with IP67-rated seals to protect open connections during washdowns. Connections between outlets and plugs should also feature an IP67-rated seal to protect plugs and outlet contacts from dust and moisture. In addition, stainless steel faceplates with rear sealing gaskets that offer at least an IP44-rating provide a protective seal from moisture and debris, while enclosures and surface-mount boxes with a NEMA 4X rating will protect equipment and termination points.
When selecting cable and connectivity for harsh environments, designers should consult a trusted manufacturer with copper and fiber solutions in a range of performance levels for a variety of application environments. Some suppliers of industrial cabling and connectivity may not offer the latest Ethernet solutions designed to support higher speeds, as high-speed performance still isn’t required for many industrial systems. However, due to the continuing proliferation of Ethernet, ruggedized cables and connectivity that support higher speeds may be needed for non-industrial applications in areas still considered harsh because they’re subject to moisture, chemicals, temperatures, and other hazardous elements. For example, Wi-Fi access points placed in outdoor locations require Category 6A performance at a minimum, so it is wise to find a manufacturer that offers IP66/67-rated ruggedized connectivity available in the same copper and fiber performance levels as those made for typical commercial environments.
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- Protecting Ethernet Connections in Industrial Environments - April 14, 2020