Emi Interference; Grounding; Installation Space - 3Com Switch 7700 Installation Manual

P R E P A R I N G F O R

4.2.4. EMI Interference

The installation of the switch can be affected by electromagnetic interference (EMI) sources. The interference from
both inside and outside the equipment or the system affects the equipment in two ways: radiated interference and
conducted interference.
Electromagnetic wave interference in the air is called radiated interference. Electrical coupling, magnetic coupling
and electromagnetic coupling are conducted interference.
To prevent EMI interference:

4.2.5. Grounding

A good grounding system is necessary for a switch to work reliably and the important guarantee of lightning
protection, anti-interference and anti-static. You should provide a grounding system for the switch to insure that:

4.2.6. Installation Space

The Switch 7700 is a complex piece of equipment so it is necessary to make arrangements for the installation
position, power supply, and cabling, as shown in Figure 14.
For better heat dissipation and equipment maintenance, 3Com recommends that you keep the front and back of the
switch more than 1 meter away from the walls or other devices. The sides of the switch should be at least 0.8 meters
away from the walls. If the optional cabinet is installed, the clear height of room should be more than 3 meters,
inclusive.
26
I N S T A L L A T I O N
Be sure the equipment and the floor are well connected to the earth ground.
Keep the room dustproof.
Maintain suitable temperature and humidity.
Wear an anti-static wrist strap and work clothes touching the circuit board with any part
of your body.
Adopt effective measures to reduce the interference on a switch caused by the power
supply system
Separate the working ground of the switch from the ground device of the power supply
equipment or lightning-protection ground device as much as possible
Keep the switch far away from high-frequency devices working in high currents
Use electromagnetic shielding, filter and reduce grounding resistance when necessary
Contact resistance of the grounding bar is less than 0.1 ohm (it must pass the test of
12V/25A)
The grounding resistance value of the equipment room is less than 1 ohm
The ground wire PGND is composed of alternated green and yellow wires. The
sectional area of the grounding wire cannot be smaller than 25mm
shall be kept as short as possible during the project construction
Preventive measures have been taken to prevent erosion of the grounding bar
The grounding bar is fixed with combined screws to avoid loosening
. The ground wire
2