HP 9000 rp8420 Server - User Service Guide, Fifth Edition

Site Preparation 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 term 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 British thermal units. The amount of heat required to raise one pound of water 1° F/hr, a common
measure of heat transfer rate.
C
CFM 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.
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. Refer
tohttp://www.picmg.org/compactpci.stm for details.
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.
EIA unit The Electronic Industries Association (EIA) defines this unit of measurement to be 1.75 in. in
height. So then, 1U equals 1.75 in. (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 because of 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 Kilovolt-amperes. (1000 x volt-amperes)
L-N
Latent cooling
capacity
The capability of an air-conditioning system 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-Hz 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
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