QSW-4700 Series Switches Hardware Installation and Reference Guide
Preparing for Installation
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2.2.4. Anti-interference Requirements
The AP is susceptible to external interference by capacitive coupling, inductive coupling,
electromagnetic waves, common impedance (ground) coupling, or conduction over power lines,
signal lines and output lines. Note that:
•
In a TN earthing system, use a 3-wire single-phase outlet that has a protective earth
(PE) contact to allow the filter circuit in the device to eliminate interference from the
power grid.
•
The switch should be located far away from the large power radio launch pad, radar
launch pad, and high-frequency large-current devices.
•
Use EMI shielding such as shielded interface cables to minimize interference when
necessary.
•
Route interface cables only indoors to prevent signal ports from getting damaged by
overvoltage or overcurrent caused by lightning strikes.
2.2.5. Grounding Requirements
A proper grounding system is the basis for stable and reliable running and is indispensable for
preventing lightning strikes and interference. Carefully check the grounding conditions at the
installation site according to the grounding specifications, and complete grounding properly
based on the actual situation.
2.2.5.1. Safe Grounding
Ensure that the rack and power distribution device are securely grounded when the switch uses
the AC power supply. Otherwise, electric shock may occur when the insulation resistance
between the power supply inside the switch and the chassis becomes small.
2.2.5.2. Lightning Grounding
The lightning protection system of facilities is standalone, and is composed of a lightning rod, a
lower conductor, and a connector connected to the grounding system. The grounding system is
usually used for power reference grounding and safety grounding of the rack. Lightning
grounding is required only for facilities and is not required for the switch.
2.2.5.3. EMC Grounding
Grounding required for electromagnetic compatibility includes shielded grounding, filter
grounding, noise and interference suppression, and level reference, which contribute to the
overall grounding requirements. The grounding resistance should be smaller than 1 Ohm. The
back panel has one Grounding Stud.
Figure 2-1 Grounding
