Cleanness - H3C S12508-AC Installation Manual

Lasting high relative humidity can cause poor insulation, electricity creepage, mechanical property
change of materials, and metal corrosion. Lasting low relative humidity can cause washer contraction
and ESD and bring problems including loose captive screws and circuit failure.

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 10 Dust concentration limit in the equipment room
Substance
Dust particles
NOTE:
Dust particle diameter ≥ 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 11 Harmful gas limits in the equipment room
Gas
SO
2
H S
2
NO
2
NH
3
Cl
2
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:
If AC power is used, use a single-phase three-wire power receptacle with 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 overvoltage or
overcurrent caused by lightning strikes.
Grounding
Using a good grounding system to protect your switch against lightning shocks, interferences, and ESD
is essential to the operating reliability of your switch.
Concentration limit (particles/cu m)
≤ 3 x 10 (no visible dust on the tabletop over three days)
4
Table 1 1.
Average (mg/m 3 )
0.3
0.1
0.004
1.0
0.1
20
Max. (mg/m 3 )
1.0
0.5
0.15
3
0.3