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2-2
Temperature/Humidity
You must maintain a proper temperature and humidity in the equipment room. Long-term high humidity
may lead to bad insulation, electricity leakage, mechanical property changes, and metal corrosion.
However, if the relative humidity is two low, captive screws may become loose as the result of
contraction of insulation washers and static electricity may be produced in a dry environment to
jeopardize the circuits on the device. High temperature is the most undesirable condition, because it
accelerates aging of insulation materials and can thus significantly lower reliability and service life of
your switch.
For the temperature and humidity requirements of different models, refer to
Table 1-1.
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 2-1 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.
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,
and 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 2-2 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
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:
z As the AC power system is a TN system, use a single-phase three-wire power socket with
Protection Earth (PE) to effectively filter interference from the power grid.