Emc Ground; Emi Consideration - D-Link DES-7200 Hardware Installation Manual

2.3.3

EMC Ground

The gr ound r equired f or E MC des ign i ncludes s hielding gr ound, f ilter gr ound, noise a nd
interference suppression, and level reference. All the above constitute the comprehensive
grounding r equirements. T he gr ounding r esistance s hould be less t han 1. T he
DES-7210/7206 chassis is installed with two grounding posts, as shown in Figure 2-5. Post 1
is i nstalled f or s hell protection a nd p ost 2 i s installed f or c ircuit working. T he t wo ar e
converged on the grounding post of the cabinet.
Figure 2-5 Schematic Diagram for the Grounding of the DES-7210/7206
The system cables must ensure the normal working of the equipment. Before you connect
the cables, please carefully read the following precautions.
2.3.4

EMI Consideration

Various i nterference s ources, f rom ei ther o utside or i nside the equ ipment or app lication
system, af fect t he s ystem in t he c onductive ways s uch as c apacitive c oupling, i nductive
coupling, and electromagnetic radiation.
There are two types of electromagnetic interferences: radiated interference and conducted
interference, depending on the type of the propagation path.
When the energy, often RF energy, from a component arrives at a sensitive component via
the s pace, t he en ergy i s k nown as r adiated interference. T he i nterference s ource c an be
both a par t of t he i nterfered s ystem and a completely electrically isolated unit. Conducted
interference r esults from t he electromagnetic wire or signal cable c onnection between the
source and the sensitive component, along which cable the interference conducts from one
unit to another. Conducted interference often affects the power supply of the equipment, but
can be c ontrolled b y a f ilter. R adiated i nterference m ay af fect an y s ignal pat h in t he
equipment, and is difficult to shield.
1. Effective measures should be taken for the power system to prevent the interference
from the electric grid.
2. The working ground of the routers should be preferably separated and kept as far away
as pos sible f rom t he gr ounding d evice of t he po wer equ ipment or t he an ti-lightning
grounding device.
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DES-7200 Hardware Installation Guide