Site Preparation Guide, Second Edition - HP Integrity cx2620 Server

Glossary
A-B
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
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.
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/pdf/PICMG3_xIntro.pdf 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 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 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.
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 operational
continuity. The documents cover both physical requirements including: Space Planning,
Temperature, Humidity, Fire, Earthquake, Vibration, Transportation, Acoustical, Air Quality
and Illumination; and electrical criteria including: Electrostatic Discharge (ESD), Electromagnetic
51