Recently I attended the Belden Industrial Ethernet Infrastructure Design Seminar and one of the sessions that I sat in on was regarding selecting copper and fiber cable. This event has traditionally focused on networking topics but the cable sessions attracted attendees seeking proficiency in end to end systems.
The fact that the majority of industrial network failures occur due to signal transmission issues is a very good reason to be more knowledgeable about cabling solutions. Downtime costs for mission critical networks can range from $25,000/hour for an oil pipeline to $45,000/hour for a power plant.
If damaged or unsuitable cable is at the root of an outage, its duration can be lengthy because it is difficult to troubleshoot cable issues. With cable then, there is a real incentive to install the right product for the job the first time. With this in mind, let's consider industrial Ethernet cabling options.
Four pair copper cable is shown on top and fiber cable is shown on the bottom. Signals are transmitted via copper when using copper cable and by light when using fiber cable./p>
Two of the key criteria that differentiate the use of copper or fiber optic cable are the length of the network cabling segments and the rate of data transmission.
If the cable run lengths are long and the data volume is high, then fiber cable may be the obvious choice, and you can move on to selecting a specific fiber cable. Alternatively, if the runs are short and the data volume fits within copper's capacity (though don't forget to plan ahead by allowing for higher data requirements in the future), then copper it is and again you can move onto choosing the right copper cable for the application.
If the requirements are somewhere in the middle, you may want to consider additional general differences between copper and fiber Ethernet cable.
Here are some general differences that distinguish copper and fiber cable:
Thus if you need lightweight cable that is immune to electrical noise and is not a spark hazard then fiber cable is most likely the right fit and you can move onto selecting a specific fiber cable.
Whether you are clear already if copper or fiber is right for the project, or you suspect that copper might do the trick with the right protection, your final choice should consider the external environment and the stresses the cable will face. Remember the high cost of failure when mission critical networks go down and cable is the root cause? Your project will be well served by digging a little deeper into the specific application requirements.
In the presentation I saw at the Belden Design Seminar, Kyle Mrkva, a cable product line manager, and Brian Shuman, a cable product development engineer went into a lot of detail on selecting just the right copper or fiber industrial Ethernet cable.
In this article I am going to discuss jacketing only, and will explore other selection criteria in future articles.
Here are some of the questions to ask about a particular application before selecting a particular jacketing for a cable:
It is because of these environmental and usage conditions that commercial (office) Ethernet cable or any other non-industrial cable is unsuitable. An article from Designworld.com makes this point with shocking clarity.
The cable jacket can adapt a cable for particular environmental conditions, as shown in the following table:
Just as knowing your application is vital to selecting the right switches, routers and firewalls for an industrial Ethernet network, it is also vital in selecting the right cable. When it comes to industrial Ethernet cable, long runs and high data volumes call for fiber cable. For short runs and average data requirements, copper cable will do the job. Next consider the operating environment and mechanical stresses the cable will face to help you zero in on a final choice.
What is your approach to selecting cable for industrial Ethernet cable? I look forward to hearing your ideas.
* A plenum is a space use for air circulation for heating and ventilation systems. Cable may be located in a plenum and if there is a fire, the cable will burn and spark. To avoid this, plenum cable is coated with a fire retardant that does not give off toxic gases and smoke as it burns.