Glossary
Latent cooling capacity
Glossary
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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
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
Interference (EMI), Lightning and AC Power Fault,
Steady State Power Induction, Corrosion, DC
Potential Difference, Electrical Safety and Bonding
and Grounding.
O-R
PCA Abbreviation for Printed Circuit Assembly also
referred to as a Printed Circuit Board (PCB).
PCI Currently, the most popular local I/O bus, the
Peripheral Component Interconnect (PCI) bus was
developed by Intel and introduced in 1993.
PICMG A consortium of companies involved in
utilizing PCI for embedded applications. The PCI
Industrial Computer Manufacturers Group (PICMG)
controls the PICMG specification.
Power factor The ratio of true power to apparent
power in an AC circuit. In power conversion
technology, power factor is used in conjunction with
describing the AC input current to the power supply.
RMS Root-mean-square (RMS) refers to the most
common mathematical method of defining the
effective voltage or current of an AC wave. To
determine RMS value, three mathematical
operations are carried out on the function
representing the AC waveform: (1) The square of the
waveform function (usually a sine wave) is
determined. (2) The function resulting from step (1)
is averaged over time. (3) The square root of the
function resulting from step (2) is found.
S-T
Theoretical maximum power consumption
Represents the maximum wattage of a given
configuration, assuming worst-case conditions
(thermal tolerances, workloads, and so forth) on all
system components. It is extremely unlikely that
any customer will experience this level of power
consumption.
Tonnage The unit of measure used in air
conditioning to describe the heating or cooling
capacity of a system. One ton of heat represents the
amount of heat needed to melt one ton (2000 lbs.) of
ice in one hour. 12,000 Btu/hr equals one ton of heat.
True power In an AC circuit, true power is the
actual power consumed. It is distinguished from
apparent power by eliminating the reactive power
component that may be present.
Typical input current The operating current of
the product measured using a typical load and target
voltage.
Typical power consumption Represents the
expected power consumption of a given
configuration. The typical value is the approximate
power consumption that a customer will most likely
experience and can use for power budgeting
purposes.
