Black Box Explains Industrial Networking
Industrial environments present much harsher conditions than are found in typical office environments. They not only often have extremes of temperatures, humidity, dirt, and corrosive materials, they may also contain devices such as motors and mechanical switches, which cause a large amount of electromagnetic interference (EMI)
The challenge with industrial controls as well as with other electronic devices intended for use in these environments is to have them function reliably in spite of adverse conditions. This may mean using a device that’s built to withstand harsh conditions, protecting the device in a specialized cabinet, or both.
Industrial networking solutions are suitable for use in:
• Military applications.
• Factory environments.
• Oil/gas drilling and mining.
• Public utilities.
• Traffic control
Extended temperature range
Many industrial devices are installed outdoors in unventilated sealed enclosures, which freeze in the winter and heat to extremely high temperatures in the summer. They and their power supplies are expected to perform over a wide temperature range. Typically they’re rated so you can select one appropriate to your environment.
Operating temperature tolerances are defined as:
• Standard: 0° to +40° C (32° to 104° F)
• Hardened: -25° to 60° C (-13° to +140° F)
• Extreme: -40° C to +75° C (-40° to +167° F)
Because industrial components are sealed against contaminants and also because they’re often installed inside enclosures, they rely on air convection rather than fans for cooling.
Components for office or data center use are usually either freestanding or mounted on 19" rails in a cabinet or rack. Industrial devices, on the other hand, are usually panel mounted by bolting them
to a flat surface, or they may be DIN rail mounted.
DIN rail is an industry-standard metal rail that is used both wallmounted or rackmounted. Industrial devices mount directly on the rail or may come with separate DIN rail brackets.
The power supplied to industrial sites can vary tremendously. AC power varies anywhere from 60 VAC to 960 VAC, and often only DC power is supplied, with 24 VDC or 48 VDC being common.
Industrial power may be three-phase power, which is used for power transmission across power grids and is favored for large motors and heavy loads at industrial sites. It’s also frequently
“dirty” power, subject to noise, voltage fluctuations, and spikes. This inconsistent power is hard on the electronic components in industrial devices and can cause equipment damage or data loss.
Because of this variability, industrial control devices are either sold entirely separately from their power supply or are available with a choice of power supplies. Unlike ordinary networking devices, industrial controls require you to choose the correct power supply for both device and application. Industrial power supplies must be matched to both the type of power input they’ll be receiving from the power grid and the power output they’ll be expected to provide to the industrial control device.
Industrial areas are also prone to electromagnetic interference (EMI) and radio-frequency interference (RFI). Interference and noise from EMI/RFI creates unwanted signals that may interfere with network performance. Devices for industrial applications are usually built to withstand higher EMI than those intended for office or data center use. Chassis are usually shielded, and EMI signals can be absorbed by using capacitor-based circuits or through special coatings as well.
Resistance to moisture and contaminants
Moisture is the enemy of electronic components, and industrial devices are often subject to water in all its forms, from high humidity and condensation to drips and splashes. Industrial devices are also often subject to dirt, dust, oil, salt spray, and chemicals when they’re installed outdoors or indoors in an environment such as a factory floor.
For these reasons, industrial components are usually housed in hardened metal cases that are sealed against contaminants, including particulates such as airborne dust, as well as moisture, and sometimes chemicals.
One way to protect industrial devices from their environment is with an enclosure designed to seal out contaminants such as dust and moisture. These enclosures are usually NEMA rated to describe the amount of protection they provide.