3
of insulation washers and static electricity may be produced in a dry environment to jeopardize the
circuits on the device. A high temperature is the most undesirable condition, because it accelerates the
aging of insulation materials and significantly lowers reliability and service life of the switch.
For the temperature and humidity requirements of this switch, see Table 6.
Cleanness
Dust buildup on the chassis may 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 Concentration limit (particles/m³)
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 m.
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 li
mits 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:
• The AC power system is a TN system, so use a single-phase three-wire power receptacle with a
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 over-voltage
or over-current caused by lightning strikes.
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