QTech QSW-6900-56LF Series Hardware Installation And Reference Manual page 15

Installation Manual
2. Preparation before Installation
For lightning protection, refer to Appendix C.
EMC Grounding
The ground 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 grounding resistance should be less than 1Ω. There is one
grounding connector at the right bottom of the chassis of QSW-6900-56LF series switches. The
grounding connector is pasted with conspicuous warning labels.
Figure 2-1 EMC grounding
2.2.6 EMI Consideration
Various interference sources, from either outside or inside the device or application system,
affect 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 propagation path. When
the energy, often RF energy, from a 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 sensor.
Interference along the cable the interference is transmitted from one unit to another. Conducted
interference often affects the power supply of the device, but can be controlled by a filter.
Radiated interference may affect any signal path in the device, and is difficult to shield.
❖ Effective measures should be taken for the power system to prevent electric grid
interference.
❖ The working ground of the routers should be properly separated and kept as far as possible
from the grounding device of the power device or the anti-lightning grounding device.
❖ Keep the device away from high-power radio transmitter, radar transmitting station, and
high-frequency large-current device.
❖ Measures must be taken to isolate static electricity.
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