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Joule
- The mks unit of work or energy equivalent to heat generated in 1 second
by 1 ampere flowing through 1 ohm. A watt/second. A measurement of work in
time. 1 joule equals 0.0002778 watt/hours. 1 kilowatt hour is equivalent
to 3,600,000 joules.
kcmil
- Thousand Circular Mil; wire size for multiple stranded conductors over
4/0 AWG in diameter. Formerly MCM.
k - kilo,
used to express 1000 (10 to the +3rd power) times the standard unit.
kV -
kilo-Volts; 1000 Volts potential.
kVA
- kilo-Volt-Ampere; 1000 Volt Amperes; a measure of apparent power.
kW
- kilo-Watt; 1000 Watts; a measure of real power.
Lagging Load -
An inductive load with current lagging voltage. Since inductors tend
to resist changes in current, the current flow through an inductive
circuit will lag behind the voltage. The number of electrical
degrees between voltage and current is known as the phase angle. The
cosine of this angle is equal to the power factor (linear loads
only).
LAN
- Local Area Network. See Ethernet. The means by which a local community
of users and workgroups can share information and resources
electronically.
LED
- Light Emitting Diode, a high reliability, illuminating device used as an
indicator of state or status. Available in red, green, amber and blue.
Leading Load
- A capacitive load with current leading voltage. Since capacitors
resist changes in voltage, the current flow in a capacitive circuit will
lead the voltage.
Leakage Current
- The current flowing from the input terminals of the electrical
equipment and the chassis at a specified voltage.
This is a safety consideration so designs minimize this current to
typically less than 5 mA for commercial systems and less for military and
medical systems.
Line Conditioner (Power Conditioner) - A device that optimizes
the quality of commercial power. By
definition, an uninterruptible power supply (UPS) system is a line
conditioner, but a line conditioner is not always a UPS.
Line
Interactive - A UPS containing an
off-line inverter that must transfer on during a blackout, but
provides faster transfer times than an offline UPS. Power
conditioning and surge suppression are provided to protect the
connected load.
Linear Load
- A load in which the current relationship to voltage is constant based on
a relatively constant load impedance.
Load -Equipment that receives power
from a power supply, UPS or PDU.
Load Segments - Groups of receptacles on
the rear panel of a power supply or UPS that can be independently
controlled.
Load Sequencing - The ability to selectively turn on or off
specific loads in a preset pattern. Some UPS and PDU models are able to
perform load sequencing on startup and/or shutdown. Benefits include
reduced inrush and ability to start a specific load before another is
started.
Load Shedding - The ability to selectively shut off a
set of output receptacles, extending the capacity of the UPS
battery. Some PowerStation UPS models are able to shed less critical
loads by turning off selected output receptacles during an extended
power failure while maintaining power to the more critical load(s)
on the remaining output receptacles.
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