H3C Technologies H3C S5120 Series Switches - Manual (Page 10)

2
Cleanness
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 Unit Concentration limit
Dust Particles/m³
≤ 3 x 10 4 (no visible dust on the tabletop within
three days)
NOTE
The dust particle size ≥ 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 2 .
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 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:
• As the AC power system is a TN system, use a single-phase three-wire power receptacle with
Protection Earth (PE) to filter interference from the power grid.
• Keep the switch far from radio transmitting stations, radar stations, and high-frequency devices.
• Use electromagnetic shielding when necessary, for example, use shielded interface cables.
• Route interface cables only indoors to prevent signal ports from getting damaged by overvoltage or
overcurrent caused by lightning strikes.
Laser safety
The S5120-EI Switch Series is a line of Class 1 laser devices.
CAUTION:
When a fiber port on an S5120-EI switch is operating, do not stare into the fiber port because the laser
light emitted from the optical fiber might hurt your eyes.