10
Table 3 Humidity requirements
Humidity Range
Operating humidity (noncondensing) 10% to 95%
Storage humidity (noncondensing) 5% to 95%
Lasting high relative humidity tends to cause poor insulation, electricity creepage, mechanical property
change of materials, and corrosion of metal parts. Lasting low relative humidity is likely to result in loose
screws due to washer contraction, and even electrostatic discharge (ESD), which causes the circuits to
fail.
Cleanness requirements
Dust is a hazard to the operating safety of your switch. Dust buildup on the chassis may 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 4 Dust concentration limit in the equipment room
Substance Concentration limit (particles/cu m)
Dust particles
≤ 3 x 10
4
(No visible dust on desk in three days)
NOTE:
Dust particle diameter ≥ 5 μm
In addition, the equipment room should meet strict limits on salts, acids and sulfides to eliminate
corrosion and premature aging of components, as shown in Table 5.
Table 5 Harmful gas li
mits 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 requirements
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 grounding system) coupling. To
prevent EMI, perform the following steps:
• Take measures against interference from the power grid.
• Do not use the switch together with the grounding equipment or light-prevention equipment of
power equipment, and keep the switch far away from them.
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