3Com 3C13701 Installation Manual page 18

18 C 3: I
HAPTER NSTALLATION
Requirements on
Electrostatic
Discharge Prevention
Requirements on
Electromagnetic
Environment
P
REPARATION
Besides the dust specifications, the equipment room of the Router should also meet the
rigorous requirements for the content of salt, acid and sulfide. These harmful gases could
accelerate the metal erosion and aging process of some parts. The specific limits of these
harmful gases are given in the following table:
Table 10 Harmful gas limits in an equipment room
Gas
SO
2
H S
2
NH
3
Cl
2
Although many anti-static considerations have been given to 3Com 5000 Routers,
damage to the router's circuit or even the whole equipment may still happen when the
static electricity exceeds the tolerance threshold.
In the communication network to which the routers are connected, static induction
mainly comes from:
External electric fields such as outdoor high voltage power line or thunder.
■
Internal environment like flooring materials or the whole equipment structure.
■
Thus, the following should be considered to safeguard the equipment against the ESD:
Make sure that the equipment and the floor are well grounded.
■
Make sure that dust-proof measures are taken.
■
Maintain an appropriate humidity and temperature.
■
Wear an ESD-preventive wrist strap and uniform when contacting the circuit board.
■
Place the uninstalled circuit board on the anti-static workbench, with its face upward,
■
or put it into the static shielding bag.
When observing or removing the uninstalled circuit board, please touch the edge of
■
the circuit board, and avoid contacting the devices on it.
The interference sources, no matter where they come from, affect the routers with
capacitance coupling, inductance coupling, radiation of electromagnetic wave, common
impedance (including the grounding system) or conducting line (power line, signal line
and transmission line etc.).
So the following should be considered:
Take effective measures to prevent the power system from being interfered with by
■
the power grid system.
Keep the router far away from the radio launcher, radar launcher, and high-frequency
■
devices working in high current.
Use electromagnetic shielding when necessary.
■
Max. (mg/m3)
0.2
0.006
0.05
0.01