2
•
High temperature can accelerate aging of insulation materials and significantly lower the
reliability and lifespan of the switch.
Cleanliness
Dust buildup on the chassis might result in electrostatic adsorption, which causes poor contact of
metal components and contact points, especially when indoor relative humidity is low. In the worst
case, electrostatic adsorption can cause communication failure.
Table 1 Dust concentration limit in the equipment room
Substance
Concentration limit (particles/m³)
Dust
≤
3 x 10
4
(no visible dust on the tabletop over three days)
NOTE:
Dust diameter
≥
5
μ
m
The equipment room must also meet limits on salts, acids, and sulfides to eliminate corrosion and
premature aging of components, as shown in
Table 2 Harmful gas limits in the equipment room
Gas
Maximum concentration (mg/m
3
)
SO
2
0.2
H
2
S 0.006
NH
3
0.05
Cl
2
0.01
EMI
All electromagnetic interference (EMI) sources, from outside or inside of the switch and application
system, adversely affect the switch in the following ways:
•
A conduction pattern of capacitance coupling.
•
Inductance coupling.
•
Electromagnetic wave radiation.
•
Common impedance (including the grounding system) coupling.
To prevent EMI, use the following guidelines:
•
If AC power is used, use a single-phase three-wire power receptacle with protection earth (PE)
to filter interference from the power grid.
•
Keep the switch far away from radio transmitting stations, radar stations, and high-frequency
devices to make sure the EMI levels do not exceed the compliant range.
•
Use electromagnetic shielding when necessary. For example, use shielded interface cables.
•
To prevent signal ports from getting damaged by over-voltage or over-current caused by
lightning strikes, only route interface cables indoors.