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Dust and Particulate Requirements
Dust and Particulate Requirements
Exhaust fans cool power supplies and system fans cool switches by drawing in air and exhausting air out
through various openings in the chassis. However, fans also ingest dust and other particles, causing contaminant
buildup in the switch and increased internal chassis temperature. Dust and particles can act as insulators and
interfere with the mechanical components in the switch. A clean operating environment can greatly reduce
the negative effects of dust and other particles.
In addition to regular cleaning, follow these precautions to avoid contamination of your switch:
• Do not permit smoking near the switch.
• Do not permit food or drink near the switch.
Minimizing Electromagnetic and Radio Frequency Interference
Electromagnetic interference (EMI) and radio frequency interference (RFI) from the switch can adversely
affect other devices, such as radio and television (TV) receivers. Radio frequencies that emanate from the
switch can also interfere with cordless and low-power telephones. Conversely, RFI from high-power telephones
can cause spurious characters to appear on the switch monitor.
RFI is defined as any EMI with a frequency above 10 kHz. This type of interference can travel from the switch
to other devices through the power cable and power source or through the air as transmitted radio waves. The
Federal Communications Commission (FCC) publishes specific regulations to limit the amount of EMI and
RFI that are emitted by computing equipment. Each switch meets these FCC regulations.
To reduce the possibility of EMI and RFI, follow these guidelines:
• Cover all open expansion slots with a blank filler plate.
• Always use shielded cables with metal connector shells for attaching peripherals to the switch.
When wires are run for any significant distance in an electromagnetic field, interference can occur to the
signals on the wires with the following implications:
• Bad wiring can result in radio interference emanating from the plant wiring.
• Strong EMI, especially when it is caused by lightning or radio transmitters, can destroy the signal drivers
Note
To predict and prevent strong EMI, you need to consult experts in radio frequency interference (RFI).
The wiring is unlikely to emit radio interference if you use a twisted-pair cable with a good distribution of
grounding conductors. If you exceed the recommended distances, use a high-quality twisted-pair cable with
one ground conductor for each data signal when applicable.
Cisco Nexus C9316D-GX NX-OS Mode Switch Hardware Installation Guide
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and receivers in the chassis and even create an electrical hazard by conducting power surges through
lines into equipment.
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