H3C Technologies H3C S5120 Series Switches - Manual (Page 25)

17
Cleanness
Dust is a hazard to the operating safety of your device. The dust accumulated on the chassis can be
adsorbed by static electricity and result in poor contact of metal connectors or metal contact points.
Especially when the indoor relative humidity is low, electrostatic adsorption is more likely to happen. This
can not only shorten the service life of your device but also cause communications failures. The following
table lists the dust concentration limit.
Table 12 Dust concentration limit in the equipment room
Substance Concentration limit (particles/m 3 )
Dust ≤ 3 x 10 4 (no visible dust on the tabletop over three days)
Note: The dust diameter is greater than or equal to 5 μm.
Besides dust, there are rigorous limits on the content of harmful substances in the air that can accelerate
the corrosion and aging of metals, such as chloride, acid, and sulfide in the equipment room. The
equipment room must be protected against ingression of harmful gases such as SO
2
, H
2
S, NH
3
, and Cl
2
.
For specific requirements, see the following table.
Table 13 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
Electromagnetic susceptibility
The operation of your switch can be affected by external interferences, such as conducted emission by
capacitance coupling, inductance coupling, electromagnetic wave radiation, and common impedance
(including the grounding system) coupling, and leads (power cords, signaling cables and output wires).
To eliminate the interferences, pay attention to the following:
• The AC power system is a TN system, so use a single-phase three-wire power socket with a
protection earth (PE) to effectively 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 over-voltage
or over-current caused by lightning strikes.
Laser safety
The S5120-SI Switch Series is a line of class 1 laser devices.