Glossary - HP Rp3440-4 - 9000 - 0 MB RAM Manual

Glossary

A-B
Apparent power A value of power for AC circuits
that is calculated as the product of RMS current
times RMS voltage, without taking the power factor
into account.
ASHRAE Standard 52-76 Industry standard for
air filtration efficiency set forth by the American
Society of Heating, Refrigerating, and
Air-Conditioning Engineers, Inc.
ASL Above sea level.
board A printed circuit assembly (PCA). Also called
a card or adapter.
Btu/h The abbreviation for British thermal units.
The amount of heat required to raise one pound of
water one degree fahrenheit per hour, a common
measure of heat transfer rate.
C
CompactPCI The newest specification for
PCI-based industrial computers is called
CompactPCI. It is electrically a superset of desktop
PCI with a different physical form factor. See
http://www.picmg.org for details.
CFM The abbreviation for cubic feet per minute,
commonly used to measure the rate of air flow in an
air conditioning system.
Chilled water system A type of air conditioning
system that has no refrigerant in the unit itself. The
refrigerant is contained in a chiller, which is located
remotely. The chiller cools water, which is piped to
the air conditioner to cool the space.
D-K
Dehumidification The process of removing
moisture from the air within a critical space.
Derate To lower the rated capability of an electrical
or mechanical apparatus.
Downflow Refers to a type of air conditioning
system that discharges air downward, directly
beneath a raised floor, commonly found in computer
rooms and modern office spaces.
Glossary
EIA unit The Electronic Industries Association
(EIA) defines this unit of measurement to be 1.75
inches in height. So then, 1U equals 1.75 inches (1U
equals 44.45 mm).
Humidification The process of adding moisture to
the air within a critical space.
Inrush current The peak current flowing into a
power supply the instant AC power is applied. This
peak is usually much higher than the typical input
current due to the charging of the input filter
capacitors. When switching power supplies are first
turned on, they present high initial currents as a
result of filter capacitor impedance. These large
filter capacitors act like a short circuit, producing an
immediate inrush surge current with a fast rise
time. The peak inrush current can be several orders
of magnitude greater than the supply's typical
current.
KVA Abbreviation for kilovolt-amperes. (1,000 x
volt-amperes).
L-N
Latent cooling capacity An air conditioning
system's capability to remove heat from the air.
Leakage current A term relating to current
flowing between the AC supply wires and earth
ground. The term does not necessarily denote a fault
condition. In power supplies, leakage current
usually refers to the 60 Hertz current, which flows
through the EMI filter capacitors that are connected
between the AC lines and ground.
Maximum input current The operating current of
the product equal to the maximum load divided by
the minimum input voltage.
NEBS All electronic equipment has the potential to
interfere with other electronic equipment.
Interference can be caused by electromagnetic
radiation, the grounding system, the electrical
power connection, excessive heat, or blocking the
natural airflow, and connecting wires or cables. The
FCC (Federal Communications Commission)
regulates a portion of this problem through Part 15
of their rules and regulations. Even more stringent
than the FCC Part 15 requirements, Network
Equipment Building Standards (NEBS) covers a
large range of requirements including criteria for
personnel safety, protection of property, and
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