AC- AlternatingCurrent. Current flows first in one direction, then reverses
and flows the opposite direction, typically in a sinusoidal fashion. The
number of times this change takes place per second is called frequency.
AFCEA-Armed Forces Communications Electronics Association
Agent- See SNMP Agent.
Enable/Disable- The switch used to disable the Audible Alarm feature. It
does not affect the Visual Alarm indicators.
ALICE-All-purpose Lightweight Individual Carrying
Equipment, as in ALICE ruck pack.
temperature -The range of air temperature on a normal basis
surrounding the equipment.
-The current carrying capacity, expressed in amperes, of a conductor
under stated thermal conditions.
(Amp or A) -The mks unit of measure for current flow in electrical
conductors or devices. May be AC or DC Amps. One ampere equals one coulomb
passing a point in a conductor in one second. Or the
unit of measurement of electrical current produced in a circuit by 1 volt
acting through a resistance of 1 ohm.
ANSI-American National Standards
An industry group that establishes and publishes standards.
Apparent Power -Volt-Amperes, VA. The product of voltage times
current in a circuit including inductive and/or capacitive elements.
Audible Alarm -The horn that sounds when an alarm condition occurs.
AUSA-Association of the United
Audible Noise -The measure of the noise emanating from
equipment in audible frequencies. Usually represented in dBA.
AutorangingInput- Refers to
being able to automatically select input voltage. For example, the
autoranging can select either 115 or 230 VAC input, providing an input
range of 85 to 270 VAC having either a 50 or 60 Hz frequency. This covers 99+%
of the world.
Autotransformer- A transformer used to step voltage up or down. The primary and
secondary windings share common turns, and it provides no isolation.
AWG- American Wire Gauge. A gauging system used to size wire. Every increase
of 3 wire gauges is a 50% reduction in cross sectional area of the wire.
A term now used to describe the capacity or amount of traffic (data,
voice or video) a certain communications medium is capable of
Battery- An electro-chemical device used to store and generate electrical power.
Basic technologies used with UPS products include lead-acid and
Battery Backup- A battery or
a set of batteries in a UPS system. Its purpose is to provide an
alternate source of power if the main source is
-An electronic device that provides a controlled voltage and current
to a battery to maintain the battery in a fully charged state.
Modes -A Constant Current Rate of Charge Mode is used until
the battery is just below float level. Once the batteries have reached
this point, the charging mode changes to a Constant Voltage Mode (Trickle
Charge Mode) that is used to maintain the float level of the batteries.
Self Discharge -The internal current flowing in a battery when
it is not connected to a circuit. The rate of self discharge is
proportional to the storage temperature, thus batteries have a
longer self life at lower temperatures.
BEM- Battery Extension Module. A specific group of batteries in a self
contained enclosure with circuit protection and interface connector.
Bi-Directional Converter- A
device which changes (or converts) alternating-current power to
direct-current power and vice versa.
total loss of the AC utility (commercial
power). A zero-voltage condition that lasts for more than two
cycles. It may be caused by the tripping of a circuit breaker, power
distribution failure or utility power failure. This condition can lead to
data damage, data loss, file corruption and hardware damage.
Boost- See buck and
sequence of a switch or relay where the existing connection is opened
prior to making the new connection.
Breaker- See Circuit Breaker.
Converter- Switching converter topology
that employs four switching elements (full bridge) or two switching
elements (half-bridge). This topology is more often used in off-line
supplies rather than DC-DC converters. Bridge converters provide high
output power and low ripple, but are significantly more complex than other
types of converter topologies and thus are more expensive and prone to
failure. Also see Boost Regulator, Buck Regulator, Flyback Converter, Forward
Converter, Push-Pull Converter and Resonant Converter.
Brownout- The term used to describe when the power grid voltage is something less
than the normally accepted tolerance, but voltage is still present. Power
companies sometime lower voltage during power shortages to reduce load on
several customers rather than completely dump customers. It occurs more
often as an uncontrolled condition during high peak demand. Each piece of
electronic equipment has a low voltage limit it can tolerate. When this happens, computer systems can experience data corruption, data
loss and premature hardware failure.
BTU- British Thermal Unit. The
quantity of heat required to raise the temperature of 1 pound of water by
1 °F starting from 60 °F. This is equal to 1054.6 joules or 252
calories. 3.7 BTUs per hour is equivalent to 1 Watt.
Boost- A proprietary voltage regulation process used when an
overvoltage or undervoltage situation occurs in the UPS.
Undervoltage is boosted to make the voltage greater, and overvoltage
is bucked to reduce it. The result is less reliance on the UPS
battery, extending overall battery life.
Buck Regulator- A basic DC-DC switching converter topology that takes an
unregulated input voltage and produces a lower regulated output
voltage. The lower output voltage is achieved by chopping the input
voltage with a series connected switch (transistor) which applies
pulses to an averaging inductor and capacitor.
Burn In- The process of operating
newly manufactured equipment for some period of time prior to
shipment. The intent is to stabilize the electronics and eliminate
infant mortality by aging the device. The time period and conditions
(input power cycling, load switching, temperature, etc.) varies from
vendor to vendor.
circuit used to change the path of the electrical power so that it
goes around (or bypasses) its normal path. In the UPS, the bypass
circuit is used to route the power around the major electronics in
the UPS so they can be serviced without power interruption.
Communications, Computers, Intelligence, Surveillance, Reconnaissance
Calorie- A unit of heat. One calorie is the amount of energy required to raise the
temperature of one gram of water by one degree of Celsius.
Capacitor- A device that stores electrostatic energy in a manner similar to the way
an inductor stores electromagnetic energy. Often used for filtering or DC
blocking. The unit of capacitance is the Farad (F).
CBEMA- Computer and Business Equipment Manufacturers Association. Organization
originally responsible for the AC voltage disturbance tolerance
specification used by related equipment designers. Specifies overvoltage
and undervoltage events that computing equipment must withstand. Effective
December 1994, CBEMA changed its name to the Information Technology
Industries Council (ITI).
CE- European Union regulatory community symbol. Symbolizes compliance with
all applicable safety, public health and consumer protection requirements.
See UL, CSA, ETL, VDE and TÜV.
Celsius (°C)- A metric measure of temperature level, degrees Celsius.
-Cubic feet per minute, which is a measure of the volume of air
flowing in a system.
-An inductor used as part of an electrical filter that resists the
flow of current at specified frequencies, usually used to block
high-frequency transients from incoming a/c power. See Inductor.
Breaker (CB)- A resettable overcurrent protective device that
operates (trips) after a certain current level is exceeded for a certain
length of time. Common designs include thermal, magnetic and combinations
Power- Electrical power which has been conditioned and/or
regulated to remove electrical noise from the output
The ability to start the UPS from its batteries without having the Input AC present.
Common Mode (CM)- The term refers to electrical interference which
is measurable as a ground referenced signal. In true common mode, a signal
is common to both the current carrying conductors.
Common Mode Noise Rejection (CMNR)- The ability of an electronic
device, like a UPS, to block common mode noise between input and
Conduit- A flexible or rigid tubular raceway for data or power cables. Metallic
conduit is common, although non-metallic forms may also be used.
-Continental United States. Typically refers
to an electronic device designed to operate from standard US power, 120
VAC, 60 Hz.
-An electronic device that takes
on level of DC power and converts it to another level, up or down (DC/DC).A device which changes electrical
energy from one form to another, such as from alternating current to
Coulomb-The combined negative electrical charge of 6.24 X 1018 electrons.
-Circular Plastic Connector. A
type of modular connector by AMP that is less expensive than the metal
Factor -The ratio of the
non-linear peak current to the true RMS current. A sine wave has a crest
value of 1.4142. For switchmode power
supplies this ratio ranges from 2 to 4.
Load -Equipment that requires an uninterrupted power input to prevent
damage or injury to personnel, facilities, or itself.
-A circuit that crowbars or rapidly shuts down a converter's output
if a preset voltage level is exceeded. The circuit places a low resistance
shunt across the output when an overvoltage condition exists.
CSA- Canadian Standards Association, a Canadian safety agency that sets
standards for product safety. See UL, ETL, CE, VDE and TÜV.
-The measure of electrical charge
passing a particular point. Commonly measured in Amperes.
limiting- Feature that protects the electrical equipment from damage
under overload conditions such as a short circuit. The maximum output
current is automatically limited to a predetermined safe value. If the
equipment is specified for auto restart, normal operation is automatically
restored when overload condition is removed.
rating- The maximum current which
a piece of electrical equipment was designed to carry or produce.
Transformer (CT)- Usually used as a sensing device, current
transformers customarily have a one turn primary. The number of secondary
turns is determined by the sensitivity required and is terminated with a
resistor. Toroidal in shape, cores of silicon steel, nickel alloy, or
ferrite are used. Choice of core material influences cost and accuracy.