Increased Environmental Severity
Mechanical
• Shock
• Vibration M1 M2 M3
I1 I2 I3
C1 C2 C3
E1 E2 E3
Because many of the criteria are difficult to measure
accurately, this leads some designers to use their own
experience and judgement. With that in mind, it is
important to rate the described area with the highest
rating in all categories (M3 I3 C3 E3) (Figure 2) for the
following reasons:
• Mechanical: The area is subject to constant vibration
while the furnace is in operation with susceptibility
to shock each time the furnace is loaded. The entire
process area requires the use of heavy
mobile equipment.
• Ingress: Dust is always present while the factory is
in operation. Visual inspection of existing electrical
enclosures and equipment indicate that the dust
mounds atop any upward facing surface. The dust
is metallic in nature and therefore an enemy to
electronic equipment.
• Climatic/Chemical: The ambient and radiant heat
created from the process, combined especially with
the summer heat and humidity, creates a severe environment.
The transition from the environmentally
controlled operator control room and the surrounding
factory floor must be considered when planning
pathways and media since this is a prime location
for water problems due to condensate.
32 I ICT TODAY
Industrial networks are designed
to control time sensitive processes
that, if compromised, can have
a significant negative impact
on both safety and production.
Office
Ingress
• Water
• Dust
Climatic Chemical
Electromagnetic
Industrial
FIGURE 2: This chart aptly depicts the MICE rating criteria that are detailed further in the TIA-1005-A standard.
• Electromagnetic: With an 8 MW electric arc furnace
as the primary piece of equipment in this operation,
it is inevitable that there will be intense electromagnetic
fields present. Combine this with the metallic
dust suspended in the air (and a blanket of it covering
everything else), and the resulting EMI potential
is significant.
Now that the information harvesting process is completed,
the designer can proceed to media selection. The
compilation of knowledge acquired through information
harvesting helps to facilitate the selection of appropriate
pathways, components, and media with far greater
certainty of long term functional success. The media
selection results based on the information harvesting
process is as follows: