Altitude; Dust And Particles; Corrosion; Electromagnetic And Radio Frequency Interference - Dell PowerEdge 4200 Series User Manual

Altitude

Operating a system at high altitude (low pressure)
reduces the efficiency of forced and convection cooling
and can result in electrical problems related to arcing and
corona effects. This condition can also cause sealed com-
ponents with internal pressure, such as electrolytic
capacitors, to fail or perform at reduced efficiency.
Each Dell system is rated to operate at altitudes from -16
to 3048 meters (m) (-50 to 10,000 feet [ft]) and can be
stored at altitudes of -16 to 10,600 m (-50 to 35,000 ft).

Dust and Particles

A clean operating environment can greatly reduce the
negative effects of dust and other particles, which act as
insulators and interfere with the operation of a system's
mechanical components. Also, in addition to regular
cleaning, you should follow these guidelines to deter con-
tamination of the computer equipment:
•
Do not permit smoking anywhere near the system.
•
Do not permit food or drink near the system.
•
Use dust covers when the system is not in use.
•
Keep all diskettes in a closed diskette box when not
in use.
•
Close windows and outside doors to keep out air-
borne particles.

Corrosion

The oil from a person's fingers or prolonged exposure to
high temperature or humidity can corrode the gold-plated
edge connectors and pin connectors on various devices in
the computer. This corrosion on computer connectors is a
gradual process that can eventually lead to intermittent
failures of electrical circuits.
To prevent corrosion, you should avoid touching contacts
on cable connectors. Protecting the system from corro-
sive elements is especially important in moist and salty
environments, which tend to promote corrosion. Also, as
a further deterrent to corrosion, the system should not be
used in extreme temperatures, as explained in "Tempera-
ture" discussed earlier in this appendix.
C-4 Dell PowerEdge 4200 Systems User's Guide
Electromagnetic and Radio Frequency
Interference
Electromagnetic interference (EMI) and radio frequency
interference (RFI) from a computer can adversely affect
devices such as radio and television (TV) receivers oper-
ating near the computer. Radio frequencies emanating
from a computer system can also interfere with cordless
and low-power telephones. Conversely, RFI from
high-power telephones can cause spurious characters to
appear on the system's monitor screen.
RFI is defined as any EMI with a frequency above
10 kilohertz (kHz). This type of interference can travel
from the computer to other devices through the alternat-
ing current (AC) power cable and power source or
through the air like transmitted radio waves. The Federal
Communications Commission (FCC) publishes specific
regulations to limit the amount of EMI and RFI emitted
by computing equipment. Each Dell system meets these
FCC regulations.
To reduce the possibility of EMI and RFI, follow these
guidelines:
•
Operate the system only with the computer cover
installed.
•
Ensure that all expansion slots are covered either by
a card-mounting bracket or by a metal filler bracket
and that each drive bay has a drive and/or a metal
insert installed. These brackets and metal inserts are
available from Dell.
•
Ensure that the screws on all peripheral cable con-
nectors are securely fastened to their corresponding
connectors on the back of the computer.
•
Always use shielded cables with metal connector
shells for attaching peripherals to the computer.
To prevent the possibility of RFI from a computer affect-
ing TV reception, follow these guidelines:
•
Keep any TV set at least 6 ft away from the com-
puter system.
•
Use cable TV when possible.
•
Use a directional outdoor TV antenna.
•
Attach line filters to the TV set.
•
Use 75-ohm coaxial cable for the TV set rather than
twin-lead antenna wire.