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Active Filter - Any of a
number of sophisticated power electronic devices for eliminating
harmonic distortion.
Alternating Current (AC)
- Electrical current that continually reverses direction,
with this change in direction being expressed in Hertz,
or cycles per second.
Alternating Voltage - A voltage
which periodically changes its polarity.
Ambient Temperature - The
average temperature of the surroundings.
A or Amp (Ampere) - A unit
that measures the strength/rate of flow of electrical current.
Ampere-Hour Capacity - The
quantity of electricity measured in ampere-hours (Ah) which
may be delivered by a cell or battery under specified conditions.
Ampere-Hour Efficiency -
The ratio of the output of a secondary cell or battery,
measured in ampere-hours, to the input required to restore
the initial state of charge, under specified conditions
(also coulombic efficiency).
Battery - Two or more electrochemical
cells electrically interconnected in an appropriate series/parallel
arrangement to provide the required operating voltage and
current levels. Under common usage, the term "battery"
is often applied to a single cell.
Black-out - The failure of
electric power for a general region.
Brownout - A temporary drop in electric power without
the power going completely off. A brownout may make the
computer screen flicker, and can cause loss of data that
has been entered but not saved yet.
Bypass - A low-resistance connection between two
points in an electric circuit that forms an alternative
path for a portion of the current. Also called shunt.
Capacitance - The property
of a capacitor that determines the quantity of electric
energy that it can store.
Capacitor - A device consisting
of two conducting surfaces separated by an insulator and
having the ability of storing electric energy. Also called
a condenser.
Capacity - The total number
of ampere-hours (or watt-hours) that can be withdrawn from
a cell/battery under specified conditions of discharge.
Cell - The basic electrochemical
unit used to generate or store electrical energy.
Charge - The conversion of
electrical energy, provided in the form of a current from
an external source, into chemical energy within a cell or
battery.
Circuit - A continuous loop
of current (i.e. incoming "hot" wire, through
a device, and returned by "neutral" wire).
Circuit Breaker - The most
common type of "overcurrent protection." A breaker
trips when a circuit becomes overloaded or shorts out.
Continuous Discharge - A
test in which a cell/battery is discharged to prescribed
cut-off voltage.
Cos phi - Cos phi is also
known as Power Factor and represents the proportion between
active power (W) and apparent power(VA). The range of cos
phi is between 0 and 1 (Ex. Resistive charges such as light
bulbs and heating elements have a cos phi = 1. The inductive
charges have different cos phi, e.g. electric handtools
is ~ 0,97; electric motor is 0,7-0,8; strip light, welding
transformer is ~ 0,5).
Crest Factor - It is the
proportion between the peak value and the efficient value
of the current absorbed by the load. In the test on UPS,
the norm EN50091 provides for a non linear load a crest
factor = 3.
Critical Load - Devices and
equipment whose failure to operate satisfactorily jeopardizes
the health or safety of personnel, and/or results in loss
of function, financial loss, or damage to property deemed
critical by the user.
Cumulative Capacity - The
total number of ampere-hours (or watt hours) that can be
withdrawn from a cell/battery under specified conditions
of discharge over a predetermined number of cycles or the
cycle life.
Current Distortion - Distortion
in the ac line current.
Deep Discharge - Withdrawal
of at least 80% of the rated capacity of a cell/battery.
Depth of Discharge - The
ratio of the quantity of electricity (usually in ampere-hours)
removed from a cell/battery on discharge to its rated capacity
(usually expressed in %).
Dip. See Sag. - Distortion.
Any deviation from the normal sine wave for an ac quantity.
Direct Current (DC) - DC
is the unidirectional flow or movement of electric charge
carriers, usually electron. The intensity of the current
can vary with time, but the general direction of movement
stays the same at all times. As an adjective, the term DC
is used in reference to voltage whose polarity never reverses.
Discharge - The conversion
of chemical energy of a cell/battery into electrical energy
and withdrawal of the electrical energy into a load.
Discharge Rate - The rate,
usually expressed in amperes, at which electrical current
is taken from the cell/battery.
Dropout - A loss of equipment
operation (discrete data signals) due to noise, sag, or
interruption.
Dropout Voltage - The voltage
at which a device will release to its de-energized position
(for this document, the voltage at which a device fails
to operate).
Electric Field - A field
of force that exists between positively and negatively charged
surfaces. In a capacitor, the field is assumed to consist
of lines of force which extend through the dielectric from
the positive to the negative plate.
Energy Density - The ratio
of the energy available from a cell or battery to its volume
(Wh./L). Also used on a weight basis (Wh/kg).
Fault - Generally refers
to a short circuit on the power system.
Fault, Transient - A short
circuit on the power system usually induced by lightning,
tree branches, or animals which can be cleared by momentarily
interrupting the current.
Field - The windings of an
electric generator which are supplied with dc to produce
the steady electromagnetic field. Generators used for demonstration
purposes may use permanent magnets to produce the magnetic
field.
Filter - An electrical circuit
which is part of every Lutron dimmer that is intended to
reduce radio frequency interference and lamp buzz.
Flicker - Impression of unsteadiness
of visual sensation induced by a light stimulus whose luminance
or spectral distribution fluctuates with time.
Frequency - The number of
cycles of alternating voltage or current which occur during
a particular amount of time, usually one second.
Frequency Deviation - An
increase or decrease in the power frequency. The duration
of a frequency deviation can be from several cycles to several
hours.
Frequency Response - In power
quality usage, generally refers to the variation of impedance
of the system, or a metering transducer, as a function of
frequency.
Front Accessible Service Switch
(FASS) - An air-gap switch that can be conveniently activated
without removing the wallplate of a control. When switch
is turned off, power is completely removed from the device's
load circuit by an air-gap switch.
Fuses - Removable devices
that link a circuit at the fuse box. Fuse connections blow
apart and break the circuit if an overload or short occurs.
Generators - Machines used
to convert mechanical energy into electric energy. They accomplish
this by causing one or a series of interconnected coils to
either cut or be cut by a strong magnetic field.
Ground - A conducting connection,
whether intentional or accidental, by which an electric circuit
or equipment is connected to the earth, or to some conducting
body of relatively large extent that serves in place of the
earth. Note: It is used for establishing and maintaining the
potential of the earth (or of the conducting body) or approximately
that potential, on conductors connected to it, and for conducting
ground currents to and from earth (or the conducting body).
Harmonic (component) - A component
of order greater than one of the Fourier series of a periodic
quantity.
Harmonic Content - The quantity
obtained by subtracting the fundamental component from an
alternating quantity.
Harmonic Distortion - Periodic
distortion of the sine wave. See Distortion and Total Harmonic
Distortion (THD).
Harmonic Number - The integral
number given by the ratio of the frequency of a harmonic to
the fundamental frequency.
Harmonic Resonance - A condition
in which the power system is resonating near one of the major
harmonics being produced by nonlinear elements in the system,
thus exacerbating the harmonic distortion.
Hertz (Hz) - The unit of frequency.
One hertz is equal to 1 cycle per second (cps).
Hot, Neutral, Ground - The
three most common circuit wires. The hot brings the current
flow in, the neutral returns it to the source, and the ground
is a safety route for returning current. The ground and neutral
are joined only at the main service panel.
Impulse - A pulse that,
for a given application, approximates a unit pulse or a
Dirac function. When used in relation to the monitoring
of power quality, it is preferred to use the term impulsive
transient in place of impulse.
Impulsive transient - A sudden
non-power frequency change in the steady state condition
of voltage or current that is unidirectional in polarity
(primarily either positive or negative).
Inductance - The property
of a circuit or coil that causes an electro-motive force
to be set up due to a change of current in the circuit or
coil.
Inductor (L) - A coil of
wire which has the property of inductance.
Interharmonic (component)
- A frequency component of a periodic quantity that is not
an integer multiple of the frequency at which the supply
system is designed to operate (e.g. 50 Hz or 60 Hz).
Inverter - An electric or
electronic device for producing alternating current from
direct current.
ISO 9001 - A series of quality
standards established by the International Organization
of Standardization, that outline the requirements for quality
management systems.
Isolated Ground - An insulated
equipment grounding conductor run in the same conduit or
raceway as the supply conductors. This conductor is insulated
from the metallic raceway and all ground points throughout
its length. It originates at an isolated ground-type receptacle
or equipment input terminal block and terminates at the
point where neutral and ground are bonded at the power source.
See NFPA 70-1990, Section 250-74, Exception #4 and Section
250-75, Exception.
Isolation - Separation of one section of a system
from undesired influences of other sections.
Life - For rechargeable batteries,
the duration of satisfactory performance, measured in years
(float life) or in the number of charge/discharge cycles (cycle
life).
Linear Load - An electrical
load device which, in steady state operation, presents an
essentially constant load impedance to the power source throughout
the cycle of applied voltage.
Load - A load is an energy
consuming device. The device can be an actual device such
as a bulb of a flash light, radio, cassette player, motor,
etc., a resistor or a constant current load.
LI - Line Interactive - UPS
with interactive functioning. The inverter works only of necessary.
LIB – Line Interactive
By-Pass
MTBF (Mean Time Between
Failures) - The MTBF indicates the UPS reliability. It depends
on many factors, such as the environmental temperature,
the components, the working frequency, the altitude and
etc.
Noise - Unwanted electrical
signals which produce undesirable effects in the circuits
of the control systems in which they occur. (For this document,
"control systems" is intended to include sensitive
electronic equipment in total or in part.)
Nominal Voltage (Vn) - A nominal
value assigned to a circuit or system for the purpose of conveniently
designating its voltage class (as 208/120, 480/277, 600).
Nonlinear Load - Electrical
load which draws current discontinuously or whose impedance
varies throughout the cycle of the input ac voltage waveform.
Normal Mode Voltage - A voltage
that appears between or among active circuit conductors.
Ohm - A unit that measures
the resistance a conductor has to electricity.
Open Circuit Voltage (OCV)
- The difference in potential between the terminals of a cell/battery
when the circuit is open (no-load condition).
Oscillatory Transient - A sudden,
non-power frequency change in the steady state condition of
voltage or current that includes both positive or negative
polarity value.
Overvoltage - When used to
describe a specific type of long duration variation, refers
to a voltage having a value of at least 10% above the nominal
voltage for a period of time greater than 1 minute.
Overcharge - Discharge past the point where the full
capacity of the cell has been obtained.
Passive Filter - A combination
of inductors, capacitors, and resistors designed to eliminate
one or more harmonics. The most common variety is simply
an inductor in series with a shunt capacitor, which short-circuits
the major distorting harmonic component from the system.
Power Conditioner - A device
used to isolate sensitive equipment from the hazards of
dirty power. Varying degrees of protection can be provided
for electrical noise and voltage fluctuations like transient
(spikes), surges, sags (brownouts) and outages (blackouts).
Power Factor (True) - The
ratio of active power (watts) to apparent power (volt-amperes).
Rated Capacity - The number
of ampere-hours a cell/battery can deliver under specific
conditions (rate of discharge, cut-off voltage, temperature).
Recharge/Charge - The conversion of electrical energy,
provided in the form of a current from an external source
(charger), into chemical energy within a cell/battery.
Recovery Time - Time interval
needed for the output voltage or current to return to a
value within the regulation specification after a step load
or line change. Also may indicate the time interval required
to bring a system back to its operating condition after
an interruption or dropout.
Recovery Voltage - The voltage
that occurs across the terminals of a pole of a circuit
interrupting device upon interruption of the current.
Rectifier - A device which
converts ac to pulsating dc.
Sag - A decrease to between
0.1 and 0.9 pu in rms voltage or current at the power frequency
for durations of 0.5 cycles to one minute.
Self Discharge - The loss
of useful capacity of a cell or battery due to internal
chemical action.
Series - The interconnection
of cells or batteries in such a manner that the positive
terminal of the first is connected to the negative terminal
of the second, and so on. Series connections increase the
voltage of the resultant battery.
Service Life - The period
of useful like (usually in hours or minutes) of a primary
cell/battery before a predetermined cut-off voltage is reached.
Service/Supply Leads - The
incoming electrical lines that supply power to the service
panel.
Short Circuit - When current
flows "short" of reaching a device. Caused by
a hot conductor accidentally contacting a neutral or ground.
A short circuit is an immediate fault to ground and should
always cause the breaker to trip or the fuse to blow. (also
see ground fault)
Short Duration Variation - A
variation of the rms value of the voltage from nominal voltage
for a time greater than one-half cycle of the power frequency
but less than or equal to one minute. Usually further described
using a modifier indicating the magnitude of a voltage variation
(e.g. Sag, Swell, or Interruption) and possibly a modifier
indicating the duration of the variation (e.g., Instantaneous,
Momentary or Temporary).
Single Phase - The portion
of a power source that represents only a single phase of
the three phases that are often available.
Single Pole - A single pole
dimmer provides full-range dimming from one location only.
Sinusoidal - The graphical
plot of the output of an alternator.
Spike - See Surge
Surge - A brief transient
wave of voltage, current or power in an electrical circuit,
lasting for less than 1% of the power wave cycle duration.
Undervoltage - When used to
describe a specific type of long duration variation, refers
to a measured voltage having a value at least 10% below the
nominal voltage for a period of time greater than one minute.
UPS - Uninterruptible Power System is a system that
utilizes batteries or other form of energy supply to provide
continuous power (ranging from a fraction of a Watt to Mega
Watts) during brownouts and blackouts for a predetermined
timeframe ranging from seconds to hours.
Total Harmonic Distortion (THD)
- The ratio of the root-mean- square of the harmonic content
to the root-mean-square value of the fundamental quantity,
expressed as a percent of the fundamental.
Transformer - An electric device,
without moving parts, for transferring electric energy from
one or more circuits to one or more other circuits by electromagnetic
induction.
Transient - Pertaining to or
designating a phenomenon or a quantity which varies between
two consecutive steady states during a time interval that
is short compared to the time scale of interest. A transient
can be a unidirectional impulse of either polarity or a damped
oscillatory wave with the first peak occurring in either polarity.
Triplen Harmonics - A term
frequently used to refer to the odd multiples of the third
harmonic, which deserve special attention because of their
natural tendency to be zero sequence.
TVSS - Transient Voltage Surge
Suppressor.
Volt - A unit that measures
the amount of electrical pressure.
Voltage Change - A variation
of the rms or peak value of a voltage between two consecutive
levels sustained for definite but unspecified durations.
Voltage compensation - Voltage
compensation reduces changes in lighting level that occur
when air conditioners, refrigerators, and other electrical
appliances switch on/off.
Voltage Dip - See Sag.
Voltage Distortion - Distortion
of the ac line voltage. See Distortion.
Voltage Fluctuation - A series
of voltage changes or a cyclical variation of the voltage
envelope.
Voltage Imbalance (Unbalance)
- A condition in which the three phase voltages differ in
amplitude or are displaced from their normal 120 degree phase
relationship or both. Frequently expressed as the ratio of
the negative sequence or zero sequence voltage to the positive
sequence voltage, in percent.
Voltage Interruption - Disappearance
of the supply voltage on one or more phases. Usually qualified
by an additional term indicating the duration of the interruption
(e.g., Momentary, Temporary, or Sustained.)
Voltage Regulation - The degree
of control or stability of the rms voltage at the load. Often
specified in relation to other parameters, such as input-voltage
changes, load changes, or temperature changes.
Watt - A unit that measures
the amount of electrical power.
Waveform Distortion - A steady
state deviation from an ideal sine wave of power frequency
principally characterized by the spectral content of the
deviation.
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