7
Table 10 Humidity requirements
Humidity Range
Operating humidity
10% to 95%, noncondensing
Storage humidity
5% to 95%, noncondensing
Cleanness
Dust buildup on the chassis may result in electrostatic adsorption, which causes poor contact of metal
components and contact points. In the worst case, electrostatic adsorption can cause communication
failure.
Table 11 Dust concentration limit in the equipment room
Substance
Concentration limit (particles/m
3
)
Dust particles
3 x 10
4
(No visible dust on desk in three days)
NOTE:
Dust particle diameter 5 m
The equipment room must also meet strict limits on salts, acids, and sulfides to eliminate corrosion and
premature aging of components, as shown in
Table 12
.
Table 12 Harmful gas limits in an equipment room
Gas Max.
(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 a conduction pattern of capacitance coupling, inductance coupling,
electromagnetic wave radiation, or common impedance (including the grounding system) coupling. To
prevent EMI, take the following actions:
x
Take measures against interference from the power grid.
x
Use a grounding system and lighting protection system for the switch separate from those for other
electric equipment, and keep them far away as possible.
x
Keep the switch far away from radio transmitting stations, radar stations, and high-frequency
devices.
x
Use electromagnetic shielding, for example, shielded interface cables, when necessary.