48-Port Gigabit Ethernet PoE+ Managed Switch with Four 10G SFP+ Uplinks
User Manual
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2.2.7
Lightning Grounding
The lightning protection system of a facility is an independent system that consists of the
lightning rod, downlead conductor and the connector to the grounding system, which usually
shares the power reference ground and yellow/green safety cable ground. The lightning
discharge ground is for the facility only, irrelevant to the equipment.
2.2.8
EMC grounding
The grounding required for EMC design includes shielding ground, filter ground, noise and
interference suppression, and level reference. All the above constitute the comprehensive
grounding requirements. The resistance of earth wires should be less than 1 Ω. The Switch
backplane is reserved with one grounding terminal, as shown below.
2.2.9
Surge Protector Considerations
When the AC power cable is directly connected from a power outlet to the power port of the
switch, a surge protector or PDU should be adopted to prevent the switch from directly being hit
by lightning shocks. When using the surge protector: Connect the mains supply AC cable to the
surge protector; then, connect the switch to the surge protector. This can help to prevent the
current of high-voltage or lightning from passing to the switch directly through the mains supply
cable.
A surge protector for this switch is not included but should be purchased by users as required.
For how to use the surge protector, refer to its related manual.
2.2.10
EMI Consideration
Electro-Magnetic Interference (EMI), from either outside or inside the equipment or application
system, affects the system in the conductive ways such as capacitive coupling, inductive coupling
and electromagnetic radiation.
There are two types of electromagnetic interferences: radiated interference and conducted
interference, depending on the type of the transmission path.
When the energy, often RF energy, from one component arrives at a sensitive component via the
space, the energy is known as radiated interference. The interference source can be either a part
of the interfered system or a completely electrically isolated unit. Conducted interference results
from the electromagnetic wire or signal cable connection 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 controlled by a filter.
Radiated interference may affect any signal path in the equipment and is difficult to shield.
Effective measures should be taken for the power system to prevent the interference from
the electric grid.
The grounding device of the switch must not be used as the grounding device of the
electrical equipment or anti-lightning grounding device. In addition, the grounding device
