H3C Technologies H3C S9500E Series Switches - Manual (Page 28)

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Table 9 Dust concentration limit in the equipment room
Substance Concentration limit (particles/m 3 )
Dust particles ≤ 3 x 10 4 (No visible dust on tabletop over three days)
IMPORTANT:
Dust particle diameter ≥ 5 μm
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 10 .
Table 10 Harmful gas limits in the equipment room
Gas Average (mg/m 3 ) Max. (mg/m 3 )
SO
2
0.3 1.0
H
2
S 0.1 0.5
NO
2
0.004 0.15
NH
3
1.0 3
Cl
2
0.1 0.3
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:
• 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.
• Use electromagnetic shielding, for example, shielded interface cables, when necessary.
• Route interface cables only indoors to prevent signal ports from getting damaged by overvoltage or
overcurrent caused by lightning strikes.
Grounding
Using a good grounding system to protect your switch against lightning shocks, interferences, and ESD
is essential to the operating reliability of your switch.
Make sure the resistance between the chassis and the ground is less than 1 ohm.
Cooling
Plan the installation site for adequate ventilation.
• Leave at least 10 cm (3.94 in) of clearance around the air intake vents and exhaust vents.
• Equip a good cooling system for the installation site.