Temperature
Relative Humidity
0ºC-50ºC 10%-90%
The ambient temperature and humidity are measured at the point that is 1.5 m above the floor and 0.4 m before the
equipment when there is no protective plate in front or back of the equipment rack.
2.2.3 Cleanness Requirements
Dust poses a severe threat to the running of the equipment. The indoor dust falling on the equipment may be
adhered by the static electricity, causing bad contact of the metallic joint. Such electrostatic adherence may occur
more easily when the relative humidity is low, not only affecting the useful life of the equipment, but also causing
communication faults. Table 2-2 shows the requirements for the dust content and granularity in the equipment room.
Table 2-2 Requirements for the dust content and granularity in the equipment room
Maximum diameter (
μ
m)
0.5
1
3
5
Maximum density (Particles/m
3
)
1.4 x 10
7 x 10
2.4 x 10
1.3 x 10
Apart from dust, the salt, acid and sulfide in the air in the equipment room must also meet strict requirements, as
such poisonous substances may accelerate the corrosion of the metal and the aging of some parts. The equipment
room should be protected from the intrusion of harmful gases such as sulfur dioxide, sulfured hydrogen, nitrogen
dioxide, and chlorine), whose requirements are listed in Table 2-3.
Table 2-3 Requirements for harmful gases in the equipment room
Gas
Average (mg/m
3
)
Maximum (mg/m
3
)
Sulfur dioxide
0.2
1.5
Sulfured hydrogen
0.006
0.03
Nitrogen dioxide
0.04
0.15
Ammonia
0.05
0.15
Chlorine
0.01
0.3
2.2.4 EMI
During applications, the switch may be subject to external interferences that affect the device through conduction
manners such as capacitance coupling, inductive coupling, electromagnetic wave emission, common impedance
(including grounding systems), and wires (power cables, signal cables and outgoing transmission cables). For that
purpose, note that:
For the AC power supply system TN, single-phase three-core power socket with protective earthing
conductors (PE) should be adopted to effectively filter out interference from the power grid through the
filtering circuit.
The switch should be located at places free from large power radio launch pad, radar launch pad, and
high-frequency large-current devices.
If necessary, electromagnetic shielding should be adopted. For example, use interface cables to shield
cables.
