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• Inductance coupling.
• Electromagnetic wave radiation.
• Common impedance (including the grounding system) coupling.
To prevent EMI, perform the following tasks:
• If AC power is used, use a single-phase three-wire power receptacle with protection earth (PE)
to filter interference from the power grid.
• Keep the switch far away from radio transmitting stations, radar stations, and high-frequency
devices to make sure the EMI levels do not exceed the compliant range.
• Use electromagnetic shielding, for example, shielded interface cables, when necessary.
• To prevent signal ports from getting damaged by over-voltage or overcurrent caused by
lightning strikes, route interface cables only indoors.
Grounding
Using a good grounding system to protect your switch against lightning shocks, interferences, and
ESD is essential to the operating reliability of your switch. Make sure the resistance between the
chassis and the ground is less than 1 ohm. For more information about the grounding methods for
the switch, see "Installing the switch."
Power supply
To ensure that the switch has a good power supply system, implement power planning as follows:
1. Calculate the total power consumption
The total power consumption of a switch is determined mainly by its configurations including
types and quantities of cards and fan tray power consumption. It also includes PoE power
consumption if the switch provides PoE power. For more information about the total power
consumption of the switch, see "Appendix A Chassis views and technical specifications."
2. Select power modules according to the total power consumption
To ensure correct operation of the switch, make sure the maximum output power of the power
module that supplies power to the switch is higher than the total power consumption of the
switch. After determining the total power consumption of the switch, you can select appropriate
power modules according to the total power consumption. For more information about the
optional power module models, see "Appendix B FRUs and compatibility matrixes."
3. Verify that the power supply system on the installation site is stable and satisfies the input
requirements of the power modules.
Cooling
For adequate heat dissipation, plan the installation site according to the airflow of your switch, and
adhere to the following requirements:
• Leave a clearance of a minimum of 10 cm (3.94 in) around the air inlet and outlet vents.
• The rack for installing the switch has a good cooling system.
• The installation site has a good cooling system.