A
AC
adapter
An
external power supply for portable devices that allows them to operate from
wall-socket electricity.
AC
power plugs and sockets
Electrical
connectors used with alternating current.
AC
power
Electric
power where the current reverses direction periodically.
AC/AC
converter
A
power converter where the input and output are both alternating current but
may differ in frequency or other characteristics.
AC/DC
receiver design
A
radio receiver that can operate from either alternating current or direct
current wall socket power.
AC/DC
conversion
Rectification
of AC current, so that current flows in only one direction.
active
rectification
A
circuit where rectifier devices are externally controlled to change AC to
current flowing in one direction.
actuator
An
end device of a control system, that manipulates a physical variable such as
a valve opening or position of a machine part.
adaptive
control
A
control strategy where parameters are adjusted as the controlled process
changes.
additive
white Gaussian noise
A
noise model that is used in telecommunications to model the effects of
various random processes.
adjustable-speed
drive
Control
for a motor that allows more than one speed to be selected.
advanced
Z-transform
A
mathematical technique used to model and analyze digital systems.
affinity
laws
Mathematical
formulas that relate the speed, flow, and diameter of pumps, fans, blowers,
and turbines, useful for predicting output under varying conditions.
agbioeletric
A
brand name of a kind of vegetable oil for use in transformers.
AIEE
American
Institute of Electrical Engineers, predecessor organization to IEEE.
alpha–beta
transformation
A
mathematical technique useful in analysis of three-phase circuits.
alternating
current
Electric
current that reverses direction periodically.
alternator
An
electrical machine that converts mechanical power into AC electric power.
alternator
synchronization
The
process of synchronizing an alternator to a grid or another alternator.
aluminium
smelting
Reduction
of aluminium ore to metal, by use of large amounts of electric power.
ammeter
An
instrument that measures electric current.
amorphous
metal transformer
A
power transformer where the metallic core is made of metals cooled so quickly
that they do not form a crystal structure; such transformers can reduce some
kinds of energy loss.
ampacity
The
current carrying capacity of a conductor, in the context of electric power
wiring.
ampere
The
SI unit of electrical current.
Ampère's
circuital law
The
mathematical relation between the integral of the magnetic field over some
closed curve to the current passing through the region bound by the curve.
Ampère's
force law
The
mathematical relation between the force between two current carrying conductors
and the current flowing in them.
Ampère's
law
Ampère's
circuital law.
amplidyne
An
electric machine that allows a small current to control a much larger
current.
amplifier
A
system that produces an output that replicates an input signal but with a
larger magnitude.
amplitude
modulation
Transmission
of information by changing the magnitude of a carrier signal, for example
sending sound by radio.
analog
circuit
A
circuit where currents and voltages vary continually within some practical
range, in proportion to some signal.
analog
filter
An
analog circuit that alters some frequency-related property of a signal.
analog
signal processing
Generally,
techniques used to alter signals that rely on voltages or currents that vary
continually over a practical range.
analog
signal
A
signal whose properties (current, voltage) vary proportionally to the
information transmitted.
analog-to-digital
converter
A
circuit that produces a number proportional to the magnitude of a voltage or
current.
anode
The
terminal of an electrochemical or electronic device through which
conventional current flows inward.
antenna
A
structure which converts between electromagnetic waves in space and currents
in a conductor.
apparent
power
In
an alternating current power circuit, the product of the magnitude of RMS
voltage and current.
Apple
Computer
A
company that makes mobile telephones and computers.
arbitrary
waveform generator
A
type of signal generator that can generate almost any waveform.
arc
converter
A
device once used to generate radio waves.
arc
furnace
A
furnace that melts material by use of an electric arc.
arc
lamp
An
electric lamp that generates light from an electric arc.
arc
welder
A
device used to join metals by melting them with an electric arc.
armature
That
part of an electrical machine that converts electrical energy to mechanical
energy (or vice versa).
artificial
intelligence
A
computer system that replicates some feature of human intelligence.
artificial
neural networks
An
electrical network that mimics the function of a biological nervous system.
asymptotic
stability
A
condition of a control system where the output eventually reaches a
steady-state value in response to any input.
asynchronous
circuit
A
digital circuit where states propagate through a circuit without a
synchronizing clock impulse.
audio
and video connector
An
electrical fitting used to connect cables carrying audio or video signals.
audio
equipment
Equipment
used to handle signals at frequencies within the human range of hearing.
audio
filter
A
circuit intended to alter some frequency-related property of a signal
carrying sound information.
audio
frequency
A
signal whose frequency is within the range of human hearing.
audio
noise reduction
Reduction
of interfering signals in an audio signal.
audio
signal processing
Alteration
of any properties of a signal carrying sound information (dynamic range,
frequency response, or others).
audion
tube
An
early three electrode vacuum tube that had amplifying properties.
Austin
transformer
A
kind of isolation transformer.
automatic
gain control
A
circuit that automatically adjusts the magnitude of a signal to prevent it
from becoming too small or too large.
automatic
transfer switch
An
electrical switch used to automatically select a standby source of electrical
power when the principal source is lost.
automation
Automatic
control of a process.
autorecloser
A
circuit protection device for overhead power distribution lines which briefly
interrupts a circuit when a fault is detected, then restores the circuit in
the expectation the fault has cleared.
autotransformer
A
transformer where the primary and secondary circuits share some of the
transformer windings.
availability
factor
The
fraction of time that a power plant is available to produce power.
avalanche
diode
A
diode intended for regular operation in the reverse, avalanche breakdown,
mode. Used as a voltage reference, noise source, and in certain classes of
microwave oscillator device.
average
rectified value
The
average value of an alternating current waveform, taking the absolute value
of the waveform. The average value is generally different from the
root-mean-square value.
Contents:
Top0–9ABCDEFGHIJKLMNOPQRSTUVWXYZSee
alsoReferencesExternal links
B
backward
wave oscillator
A
type of microwave oscillator vacuum tube.
balanced
line
A
transmission line with two conductors, with equal impedances to earth ground.
ball
bearing motor
A
conceptual motor that does not use electro-magnetism.
balun
A
device that connects a balanced transmission line to an unbalanced line.
band-pass
filter
A
filter that lets through signals within a range of frequencies.
band-stop
filter
A
filter that blocks signals with a particular range of frequencies.
bandwidth
The
range of frequencies over which a system generates or uses significant signal
power.
bang-bang
control
A
controller that switches a final element on or off instead of providing a
proportional response.
Barlow's
wheel
A demonstration
of electromagnetic principles.
Bartlett's
bisection theorem
A
mathematical theorem used in network analysis.
base
load power plant
An
electric power plant that furnishes the part of load that does not vary
during a day.
battery
An
electrochemical device that produces electric power from chemical reactions.
battery
eliminator
An
AC adapter, which allows battery operated equipment to run on wall-socket AC
power.
Bayer
filter
An
optical filter used in color digital cameras.
beam
tetrode
A
type of vacuum tube with four active elements plus a pair of beam forming
plates.
beat
frequency
A
frequency produced by non-linear mixing of signals at two other frequencies.
Bell
Telephone Laboratories
Formerly,
the research and development laboratory of the American Telephone and
Telegraph Corporation.
biasing
The
practice of setting the quiescent operating conditions of an amplifying
device to obtain desired response.
BIBO
stability
A
control system that produces finite outputs for any finite input.
bilinear
transform
A
mathematical technique to obtain the parameters for a digital filter to
duplicate the response of some analog filter transfer function.
bimetallic
strip
A
temperature sensing element made of two metals that have different coefficients
of expansion intimately bonded together.
Biot–Savart
law
The
mathematical relationship between a magnetic field and the current producing
that field.
bipolar
junction transistor
A
type of transistor with two kinds of charge carriers.
blocked
rotor test
A
test of an electric machine where the machine is energized but the shaft is
prevented from turning.
Blu-ray
A
type of optical disc written and read using a blue/violet laser.
Bode
plot
A
plot of the amplitude and phase frequency response of a system, where the
actual response is approximated by straight line segments.
Boolean
algebra (logic)
A
type of algebra that deals with values that can only hold values
"true" and "false", of great use in design and analysis
of digital systems.
boost
converter
Any
power converter circuit that can produce an output voltage larger than its
input voltage.
booster
A
device used to increase voltage on an electric power distribution system,
such as a motor-generator set on a DC system.
bound
charge
Electric
charge in a material that is not free to move through the material.
braking
chopper
A
device used to absorb energy from a motor to slow it down.
branch
circuit
In
building wiring, any circuit from the main panelboard to utilization
equipment or receptacles.
breakdown
voltage
The
maximum voltage a device can withstand without damage.
bridge
rectifier
A
set of rectifier diodes used to convert alternating current to direct
current.
broadcasting
Transmission
of a signal to many receivers.
brush
A
sliding electrical contact between a moving part and a stationary part.
brushed
DC electric motor
An
electric motor with brushes.
brushless
DC electric motor
An
electric motor without brushes.
Buchholz
relay
A
gas pressure sensing device for protection of oil-filled transformers.
Buck
converter
Any
power converter circuit that produces an output voltage less than its input
voltage.
Buck–boost
converter
Any
power converter circuit that can provide a voltage greater or less than its
input voltage.
Buck–boost
transformer
A
transformer that can be used to adjust voltage.
busbar
A
set of conductors used to distribute current to many branches.
bushing
An
electrical fitting used to connect external conductors to the interior of
apparatus.
Butterworth
filter
A
type of filter with the flattest possible pass band.
buzzer
An
electromechanical or electronic device that produces a sound when energized.
C
Canadian
Electrical Code
The
technical standard for building wiring in Canada.
Canadian
Standards Association
Non-profit
organization that develops electrical and other technical standards.
capacitance
The
ability of a body to hold an electrical charge.
capacitor
An
electrical component that stores energy in an electric field.
capacitor-input
filter
A
power supply network where a capacitor is the first element following the
rectfier.
capacitor
voltage transformer
In
electrical power systems, an instrument transformer for measuring voltage
that uses a capacitive voltage divider.
capacity
factor
The
ratio of energy produced by a power plant over some period, over its maximum
possible energy production in that time.
carrier
current
A
system for communications where a carrier signal is impressed on power line
wiring.
carrier
wave
A radio
wave that can be modulated (changed systematically) to carry information to a
receiver.
Category
3 cable
A
performance standard for unshielded twisted pair cables for analog voice and
low speed data circuits within a building.
Category
5e cable
A performance
standard for unshielded twisted pair cables for telephone and data within a
building.
Category
6 cable
A
performance standard for unshielded twisted pair cables for telephone and
high speed data within a building.
catenary
A
geometric form of curve, the shape of a uniform cable hanging between two
supports.
cathode
ray oscilloscope
An
electronic instrument that displays the wave shape of electrical signals on a
cathode ray tube.
cathode
ray tube
A
vacuum tube that relies on an electron beam – usually used to render images
on a fluorescent screen such as in television sets.
cathode
The
terminal of an electrochemical or electronic device from which conventional
current exits the device.
cat's-whisker
detector
A
radio detector that uses a manually-set "whisker" contact to a
crystal of galena or other material, to form a rectifying junction.
CATV
Cable
television, distribution of television programming over a wire instead of by
radio broadcast.
cavity
magnetron
A
vacuum tube that is a high power microwave oscillator, using a resonant
cavity and electrons traveling through a magnetic field.
CCFL
inverter
A
power supply to generate the voltages required to operate a cold cathode
fluorescent lamp.
CD
A
"Compact Disc" used to store digital data or digitally recorded
sound using an infra-red laser.
center
tap
A
connection on a transformer which has equal voltage to either end of the
transformer winding.
ceramic
resonator
A
piezoelectric element used to stabilize the frequency of an oscillator.
channel
Any
communication path between a signal transmitter and a signal receiver, or, a
pre-selected operating frequency for a radio system.
channel
capacity
An
upper bound on the rate at which information can be reliably transmitted over
a communication channel.
charactron
A
kind of text display vacuum tube that used an internal element to shape an
electron beam to represent the shape of letters and other symbols.
charge
pump
A DC
to DC converter circuit that uses capacitors to store energy between stages.
charge
transfer switch
A
kind of charge pump circuit.
charge-coupled
device
An
imaging sensor or data storage device that represents a signal, or pixel, by
the charge stored in a capacitor and is able to move that charge from one capacitor
to the next.
Chebyshev
filter
A
form of filter that has a steep frequency selective characteristic.
choke
An
induction coil used to block alternating current and pass direct current, or
to block high frequencies and pass lower frequencies.
chopper
A
circuit that switches on and off at a high rate, used either for power
conversion or to convert a DC signal to a more easily processed AC signal.
circle
diagram
A
representation of the voltage and current characteristics of an electrical
machine; the plot traces out a circle or part of a circle.
circuit
breaker panel
A
distribution board for electric power that uses circuit breakers as protective
elements.
circuit
breaker
An
automatically operated electrical switch that opens to interrupt a short
circuit or other fault.
circuit
theory
The
mathematical theory of electrical circuits.
Circuit
Total Limitation (CTL)
A US
National Electrical Code rule for the number of circuits in a panel board.
clamp
meter
An
ammeter that measures current with a split core that can be clamped on a
wire.
Clapp
oscillator
An
electronic oscillator circuit that uses three capacitors and an inductor.
class
of accuracy in electrical measurements
A
measure of the error produced by an electrical measuring instrument.
closed-loop
controller
Any
controller that manipulates some process variable to minimize the difference
between the current state of the variable and the desired set point, such as
temperature, flow, or others.
coaxial
cable
A
cable with an inner conductor centered inside a flexible tubular conductor,
used for radio frequency transmission lines.
Cockcroft–Walton
generator
A
kind of circuit for generating very high DC voltage.
cogeneration
Production
of electricity along with some other desired product, such as process steam
or desalinated water.
cold
cathode
An
element of a vacuum tube that emits electrons without a heating circuit.
Colossus
A
British code breaking system used during World War II.
combined
cycle
A
thermal power plant that improves efficiency with two different kinds of
energy extraction from the combustion products gas stream, such as a gas
turbine followed by a steam boiler.
communication
system
A
system intended to convey information from one place to another with an expected
degree of performance.
communications
satellite
A
satellite in Earth orbit designed for international telephone, television, or
data transmission.
commutation
cell
The
elementary switching device in a power converter circuit; it could be a transistor,
a thyristor, a mercury-arc valve, or others.
commutator
A
component of a DC electric machine that connects the rotating coils with an
external circuit through brushes.
compact
fluorescent lamp
A
fluorescent lamp with a folded or spiral tube, designed to fit in the same
space as an incandescent lamp of similar light output.
Compactron
A
brand of vacuum tube, used in some radio and television sets, that combined
multiple independent functions in one envelope.
compensation
winding
A
winding on a motor or generator to improve commutation at heavy load.
computed
tomography
Production
of images of a cross-section through an object by multiple X-ray measurements
processed in a computer.
computer
engineering
The
profession of designing computers.
computer
hardware
That
part of a computer system with physical existence.
computer
programming
The
practice of producing instructions for a computer to achieve some desired
effect.
computer-aided
design (CAD)
A
design discipline where a computer is used to produce graphical
representation of the design or to assist in calculating performance
parameters.
conduction
band
In a
conductor, the energy levels of charge carriers that are free to move through
the material.
constant
k filter
A
method formerly used for designing filters for a required characteristic.
consumer
electronics
Electronic
devices intended to be owned by consumers directly; a mobile cell phone is
"consumer electronics" but the cell site it communicates with is
not.
contactor
An automatically
controlled electrical switch (relay), used to operate motors or other
high-current loads.
continuous
Fourier transform
A
mathematical operation that expresses a signal in time as the sum of its
frequency components.
continuous
signal
A signal
that can take any value within its range.
control
engineering
The
application of control theory to practical problems.
control
system
The
equipment used to adjust some parameter of an ongoing process to regulate its
behavior to a desired goal, such as positioning a disk drive head or
regulating temperature of a furnace.
control
theory
The
mathematical study of behavior of control systems.
controllability
In
control theory, the degree to which a system can be put into any desired
state given manipulation of one variable.
controller
A
system that adjusts some variable to control a process.
copper
cable certification
The
process of testing a computer network cable installation to verify that it
meets standards.
copper
loss
That
portion of an electric machine or transformer's loss attributed to the
resistance of conductors (which are not necessarily made of copper).
corona
ring
A
component of a high-voltage system intended to smooth out the electric field
distribution around energized parts.
coulomb
The
SI unit of electric charge.
Coulomb's
law
The
mathematical relation between force, electric charge and distance.
CPU
Central
Processing Unit, the element of a computer that carries out arithmetic and
logic operations.
crest
factor
The
ratio of peak to effective (RMS) value of a waveform.
crossed-field
amplifier
A
type of microwave amplifier vacuum tube.
crosstalk
Objectionable
presence of a signal from one circuit in another circuit sharing the same
transmission path, such as a cable.
crystal
oscillator
An
electronic oscillator whose frequency is stabilized by a piezoelectric
crystal resonator element.
Ćuk
converter
One
kind of buck-boost voltage converter that uses a capacitor as an energy
storage element.
current
The
movement of electric charge.
current
density
The
current flowing per unit area of a conductor.
current
source inverter
A
type of power inverter where an inductor tends to keep a constant current
flowing in the inverter stage.
current
source
In
circuit theory, an element that produces a defined current independent of the
connected circuit properties.
current
transformer
An
instrument transformer used for measuring current in AC power systems.
current-to-voltage
converter
A
transducer that produces an output voltage in response to an input current.
cybernetics
The
science of automatic control systems.
cycloconverter
A
type of variable-frequency power converter that does not first convert AC to
DC.
D
damping
ratio
A
parameter that indicates how rapidly oscillations in a system die out, if
ever.
Darlington
transistor
An
interconnection of two transistors to provide a gain that is the product of
the individual gains.
data
compression
Any
technique that allows information to be transmitted more compactly than
originally expressed, for example, codes.
data
networks
A
network for interconnection of computers and peripherals.
DC
injection braking
A
method of slowing an AC electric motor by passing direct current through its
windings.
DC-to-DC
converter
A
circuit that takes power from a DC source and generates a different DC
voltage.
degaussing
The
process of reducing the residual magnetic field in a metallic object, such as
a ship.
delay
line
A
circuit component that introduces a delay in a signal.
delta-wye
transformer
One
type of connection of a three-phase transformer.
demand
factor
The
fraction of actual use of some quantity, related to the maximum that could be
used in a specified time.
demand
response
The
ability of a generating station or grid to follow changes in load while
maintaining voltage and frequency within acceptable limits.
demodulation
The
process of recovery of information (sound, video, data) from a modulated
carrier.
describing
function
A
method for analyzing non-linear control systems.
detector
A
circuit that demodulates a radio signal to recover information.
DIAC
A
four-layer semiconductor diode that has a predictable breakdown
characteristic.
dielectric
A
material that does not allow free flow of electric current.
digital
audio broadcasting
Transmission
of sound by digital signals over radio.
digital
circuit
A
circuit where all points on the signal path have only one of two states.
digital
computers
A
computer made of digital circuits.
digital
control
A control
system that processes signals in digital form.
digital
filter
A
filter implemented as a digital circuit.
digital
image processing
Manipulation
of an image by a digital computer.
digital
micromirror device
An
element of a kind of digital projector system.
digital
protective relay
A
power system protection device that processes signals in digital form.
digital
signal controller
A
type of microprocessor that combines a digital signal processor element with
a more general purpose microcontroller.
digital
signal processing
The
technique of modifying the properties of a signal that has been converted to
digital form.
digital
television
Transmission
of images using digital techniques.
digital-to-analog
converter
A
device that produces a voltage or current that is proportional to a digital
value sent to it.
diode
bridge
An
interconnection of diodes to rectify alternating current to direct current.
diode
A
two-terminal passive circuit element, with a preferred direction of current
flow.
dipole
antenna
A
simple form of antenna that consists of two conductors oriented end-to-end
with a feed in between them.
direct
current (DC)
Electric
current that flows in one direction only.
direct
on line starter
A
kind of motor starter that does not reduce the voltage at the motor
terminals.
direct
torque control
A
method of estimating motor torque as part of a variable speed motor drive.
discrete
cosine transform
A
mathematical technique for representing a sampled signal as a sum of cosine
waves of different frequencies.
discrete
Fourier transform
A
mathematical technique for representing a sampled signal as a sum of sine and
cosine waves of different frequencies.
discrete-time
signal
A
signal represented as a time series of samples taken at regular intervals.
displacement
current
The
effect of a time-varying electric field, which induces a magnetic field just
as the motion of electrical charges does.
display
device
Any
device that displays data from an information system, such as a watch readout
or an automatic scoreboard.
dissipation
The
loss of energy in a system, such as dielectric loss in a capacitor.
dissolved
gas analysis
A
technique for fault detection in oil-filled transformers.
distributed
control system
A
control system in which significant parts of the control process are
decentralized.
distributed-element
model
An
analysis of an electric circuit where capacitance, inductance, and resistance
are distributed along the circuit, as in a transmission line, not
concentrated in lumped components.
distributed
generation
An
electrical grid where multiple small sources contribute energy, instead of
relatively few large central generating stations.
distribution
board
A
piece of electrical switchgear which distributes electric power to multiple
branch circuits.
distribution
transformer
A
power transformer, usually used to change the utility distribution voltage to
a lower voltage for use on the customer premises.
Dolby
A
trademark for a noise reduction technique for analog sound recordings.
dot
convention
A
system for marking terminals on instrument transformers to maintain correct
polarity.
doubly
fed electric machine
An
electric machine where both moving and stationary elements have external
connections handling significant power.
downsampling
A
technique for reducing the number of signal samples processed by a digital
system; decimation.
Dqo
transformation
A
technique used to simplify mathematical analysis of polyphase electric
circuits.
droop
speed control
A
method of regulating generators so that multiple units share the load
proportional to their ratings.
dual
control theory
A
branch of control theory that deals with systems whose characteristics are
initially unknown.
dual
loop
A
method of supervising contacts and wiring in a security system, so as to
detect some faults or tampering.
DVD
Digital
Versatile Disc, a type of optical disc for distributing video recordings and
data using an orange/red laser.
dynamic
braking
A
braking system that extracts energy from a moving system to bring it to rest;
a dynamic braking system generally is not used to hold a position of a
stationary object.
dynamic
demand
A
technique for load management on an electrical grid based on frequency
measurement.
dynamic
programming
A technique
for optimization of the solution of a problem by combining solutions to
smaller sub-problems.
dynamic
random access memory
A
type of semiconductor memory where data is stored as electric charges on
capacitors; the charges must be refreshed periodically or else they will leak
away, losing the stored data.
dynamo
A
direct-current generator, whose exciting field is provided by an
electromagnet.
E
Earth
leakage circuit breaker
A
protective device that opens a circuit when stray voltage or current is
detected that would present a hazard of electric shock.
eddy
current
An
electric current induced inside a conductor exposed to a changing magnetic
field.
edge
detection
An
image processing technique used to identify boundaries of objects.
Edison
effect
The
emission of an electric current from a hot wire; Edison did not realize he'd
discovered the fundamental mechanism of the vacuum tube, thermionic emission.
electret
A
dielectric material that permanently retains an impressed electric field; the
dual to a magnet.
electric
arc
Discharge
of electric current through an open space between conductors; may be produced
intentionally as a source of intense light and heat, or may be a result of an
electrical fault.
electric
charge
The
physical property of matter that causes it to experience a force when placed
in an electromagnetic field.
electric
circuit
A
closed path through which an electric current can flow.
electric
current
The
motion of electric charges.
electric
displacement field
In
Maxwell's equations, a vector field due to electric charges.
electric
distribution systems
That
portion of an electrical grid that connects customers to substations or the
bulk transmission system.
electric
field gradient
The
rate of change of electric field with respect to distance.
electric
field
A
vector field that exerts a force on electric charges.
electric
generator
A
machine that converts mechanical energy to electrical energy by moving
conductors through magnetic fields.
electric
motor
A
machine that produces mechanical energy from electrical energy, by moving
conductors through magnetic fields.
electric
multiple unit
Use
of more than one electric locomotive on a train.
electric
potential
A
measure of the work required to move a unit electric charge in an electric
field.
electric
power conversion
Generally,
changing the form of electric power.
electric
power distribution
In
an electric grid, the network that brings power from a substation or bulk
supply to individual customers.
Electric
Power Research Institute
A
non-profit organization that carries out research on behalf of the US
electric power industry.
electric
power transmission
The
bulk movement of electric power for many customers from a generating plant to
a local distribution network, usually at high voltage.
electric
power
The
rate of transfer of electrical energy past a given point.
electric
shock
An
injury caused to people or animals by electric current.
electrical
cable
A
flexible conducting wire to carry electrical power or signals, usually
covered with an insulating material.
electrical
code
A
set of regulations for the use of electricity; they may vary from municipal
to international in scope.
electrical
conductivity
A
measure of a substance's ability to pass an electric current.
electrical
conductor
An
object that carries an electric current, with little loss.
electrical
contact
A
separable part of an electric device that carries current when touching
another contact.
electrical
discharge machining (EDM)
Shaping
of a work place by small sparks.
electrical
element
In
circuit theory, a node at which some electrical property is concentrated
(resistance, etc.).
electrical
engineering
The
profession of applying electricity to practical problems.
electrical
equipment
Apparatus
for generation, transmission or utilization of electric power.
electrical
grid
A
geographically distributed system to connect source and users of electric
power.
electrical
impedance
That
property of a circuit that resists the passage of electric current, usually
in the context of alternating current.
electrical
insulation paper
A
grade of paper used for insulation of transformers, electrical machines,
capacitors, and some cables.
electrical
insulation
A
material that resists electrical current flow.
electrical
load
A
consumer of electrical energy, turning it into light, heat, mechanical power,
data, or chemical changes.
electrical
machine
Motors
and generators, apparatus that converts between electrical power and mechanical
power.
electrical
measurements
That
branch of metrology concerned with electrical quantities.
electrical
network
A
network of electrical components and conductors.
electrical
polarity
Identification
of electrical terminals where current is flowing in the same direction
relative to the device.
electrical
steel
Any
of several types of steel used for manufacturing the magnetic field
components of machines and transformers.
electrical
substation
A
facility connecting a distribution network to a transmission network, usually
with one or more transformers.
electrical
technologist
A
specialist in applying electrical theory and technique to practical problems.
electrical
wiring regulations
The
legal framework for electrical installations in buildings.
electrical
wiring
The
installation of conductors, fixtures and protection devices for a structure
or vehicle.
electricity
meter
An
instrument to measure the electrical energy used by a customer for revenue
purposes.
electricity
pylon
A
structure, generally of wood or metal, to support wires.
electricity
The
set of physical phenomena associated with electric charges.
electrification
Applying
electric power to a process that was previously done by other means,or,
development of an electric power system in a region that previously had none.
electroactive
polymers
A
polymer that significantly changes size or shape when exposed to an electric
field.
electrocardiograph
A record
of the electrical activity of the heart.
electrochemical
engineering
The
profession of application of electrochemistry to practical problems.
electrodes
An
electrical contact that connects some medium to an electric circuit, such as
in an electrochemical cell or a vacuum tube.
electro-diesel
locomotive
A
railway locomotive with a diesel engine, generator, and electric driving
motors that can be powered by the diesel engine or the track electrical
supply.
electrodynamics
The
branch of physics that studies electrical charges and electrical currents.
electrolyte
A
liquid or solid medium that carries electric current in the form of ions.
electromagnet
A
magnet that generates a magnetic field from an electric current.
electromagnetic
compatibility
The
control of unwanted electromagnetic interference.
electromagnetic
field
The
field produced by moving electric charges and magnetic fields.
electromagnetic
induction
The
production of current in a circuit by the change of magnetic field
intersecting the circuit.
electromagnetic
radiation
Radio
waves, light and other radiation that travels through space at the speed of
light.
electromagnetic
spectrum
The
range of frequencies of electromagnetic radiation.
electromagnetic
wave equation
A a
second-order partial differential equation that describes the propagation of
electromagnetic waves through a medium or in a vacuum.
electromagnetism
The
science of electric fields, magnetic fields, currents, charges,and forces.
electromechanical
A
system that has both an electrical component and a mechanical component, such
as a motor or a relay.
electromote
An
1882 demonstration of a prototype electric trolley bus.
electromotive
force
A
difference in electrical potential between two points, such as produced by a
battery or a generator.
electron
microscope
An
instrument that provides highly magnified images by use of an electron beam.
electronic
amplifier
A
device that increases the power of an electrical signal by electronic means.
electronic
circuit
A
circuit using one or more electronic devices.
electronic
component
An
active or passive element of an electronic circuit.
electronic
control unit
In an
automobile, an embedded electronic system that controls some aspect of a
vehicle (ignition, transmission, and so on).
electronic
design automation
A
system in which a computer provides assistance to the designer of a device or
system.
electronic
engineering
The
profession of applying electronics to practical problems.
electronic
filter
A
filter that alters some frequency-related characteristic of a signal.
electronics
The
study of the flow of electrons through a vacuum, gases or semiconductors.
electronic
speed control
A
device for regulating the speed of a motor.
electrophorus
An
instrument used to produce electrostatic charge through electrostatic
induction.
electrostatic
motor
A
motor that relies on the forces generated by electric fields, instead of
magnetic fields.
electrostatics
The
study of stationary electric charges and resulting forces.
embedded
operating system
The
common operating environment that supports embedded software; it may be a
highly tailored version of a general purpose operating system, or written
solely for the purpose of embedded system operations.
embedded
software
A
firmware component of a microprocessor controlled system.
embedded
system
A
computer system that controls a device or system, with no or a minimal user
interface; for example, the ignition system in a car may have a
microprocessor to control it.
enameled
wire
Wire
insulated with a thin flexible layer of enamel, used for electrical windings.
energy
demand management
A
system to adjust energy demand to reduce costs.
energy
economics
A
branch of economics concerned with energy supply and demand.
energy
efficient transformer
A
power transformer designed to have lower than average energy loss.
energy
returned on energy invested
A
measure of how long an energy producing system takes to replace the energy it
took to make it.
energy
subsidies
Payments
to a consumer or producer of electric energy that are used as incentives for
production or consumption.
engine-generator
A
combination of an internal combustion engine and a generator, often used as a
standby power plant.
ENIAC
The
first general purpose electronic digital computer.
Epstein
frame
An
apparatus used for testing of magnetic materials.
equalization
(audio)
Adjustment
of the frequency response of a system to improve its utility.
equalization
(communications)
Adjustment
of the frequency spectrum of a signal to cancel out the effect of the
frequency response of a communication path.
equivalent
circuit
In
circuit theory, a simple combination of elements that behaves at its
terminals like a more complex combination.
equivalent
impedance transforms
A
mathematical method to determine values of an equivalent circuit.
error
correction and detection
Techniques
used to improve reliability of computer memory or communications channels by
including extra information along with the desired data.
exponential
stability
A
system that settles to a steady state after a disturbance, at a rate
proportional to exponential time.
extended
Kalman filter
A
strategy for estimating an unknown value in a non-linear system by combining
multiple measurements.
F
farad
The
SI unit of capacitance.
Faraday
shield
A solid
conductive shield around a volume, which blocks electromagnetic fields.
Faraday–Lenz
law
One
of Maxwell's equations, describing the relation between a changing magnetic
field and production of an electromotive force.
Faraday's
law of induction
The relation
between a changing magnetic field and the resulting voltage produced in a
closed path.
fast
Fourier transform
A
digital algorithm to analyze a time series of sampled data into a set of sine
and cosine frequency components.
fault
A
short circuit, open circuit, or other disruption of a power system.
fax
Facsimile,
the transmission of paper images by radio or by wire.
feed
forward
A
control system that adjusts the controlled variable based on a model of the
process and measurements of disturbances, instead of feedback from
measurement of the process.
feedback
amplifier
An
amplifier that feeds back a small sample of its output to its input, to
improve linearity.
feedback
A
system that samples part of its output and adds that to its input; feedback
may be either positive or negative, aiding or opposing the initial input
signal.
feed-in
tariff
A
premium rate paid to distributed generators to encourage alternative energy
sources.
ferrite
core
A
magnetic core for an inductor made from a metal oxide compound.
ferroelectricity
The
property of materials that spontaneously maintain an electrical polarization,
as a ferromagnetic material maintains magnetic polarization.
fiber
optic cable
A
transmission medium that uses infrared energy or light to transmit
information down a long thin transparent filament such as glass.
field
effect transistor
A
transistor that relies on modulation of conductivity of a channel instead of
injection of minority carriers as does a bipolar transistor.
field-oriented
control
A
control strategy for variable frequency drives that models the magnetic field
of the motor to control its torque.
filter
A
circuit that selectively alters a signal based on its frequency components.
filter
capacitor
In a
power supply, a capacitor that smooths the DC voltage produced by a rectifier
stage.
finite
impulse response
A
class of digital filters whose response to an impulse returns to zero in
finite time.
firmware
Software
of a computer that is never or rarely altered during its working life, for
example, the control computer program for an automotive ignition system.
Fleming
valve
The
first important vacuum tube device, used as a radio detector.
Fleming's
left-hand rule for motors
A
mnemonic to recall the relative orientation of current, magnetic field and
resulting force for electric motors.
Fleming's
right-hand rule for generators
A
mnemonic to recall the relative orientation of current, magnetic field and
resulting force for electric generators.
fluorescent
lamp
A type
of electric lamp that relies on a phosphor coating to produce visible light
from the ultraviolet light generated by a mercury discharge.
flux
linkage
In a
magnetic system, that part of the magnetic flux that passes through a given
closed path, which may be a winding.
flyback
converter
A
type of voltage converter that stores energy in an inductor.
flyback
transformer
A
type of transformer that recovers energy stored in its own core. Historically
used in the deflection circuits of CRT display systems.
forward
converter
A
type of voltage converter that relies on transformer action to couple energy
to its output circuit.
fossil-fuel
phase-out
A
plan to replace coal, oil, or natural gas fuel with other sources to produce
electrical energy.
fossil-fuel
power station
A power
plant using coal, oil, or natural gas fuel.
Fourier
series
A
set of coefficients of sine and cosine waves; this can represent a time
function as a function of frequency.
Fourier
transform
An
algorithm for converting a continuous waveform in the time domain into an
equivalent set of spectral components in the frequency domain.
free
space optical communications
Transfer
of information from point to point by a beam of light or infrared energy,
instead of a wired connection or radio waves.
frequency
changer
An
electric machine used to transfer power between two networks with different
frequencies, or, an electronic device (more usually called a frequency mixer)
that changes the frequency of an input signal to some other frequency.
frequency
modulation
A
method of impressing information on a carrier wave by changing its frequency.
frequency
response
The
measure of the output of a system in response to an input of varying
frequency.
full
load current
The
current drawn by a motor or other electrical machine at its full rated power
and standard voltage.
full-wave
rectifier
A
rectifier circuit that converts both positive and negative parts of the input
alternating current waveform into a unidirectional, direct current.
fuse
A circuit
protective device that interrupts excessive current by melting a metal strip.
fuzzy
control
A
control system that relies on fuzzy logic instead of binary true/false
conditions.
G
gain
scheduling
A
technique for control of non-linear systems that use different control
parameters based on some measurement of the process controlled.
galvanic
corrosion
Electrochemical
corrosion of one metal in contact with another.
galvanometer
An
instrument for detecting small electric currents.
gamma
ray
Electromagnetic
radiation with wavelengths shorter than ten nanometres. Strictly: radiation
that is produced in the nucleus of atoms.
gas-filled
tube
An
electron tube device that relies on the presence of gas for operation,
usually at less than atmospheric pressure.
gate
turn-off thyristor (GTO)
A
four-layer power semiconductor device that can be turned on and off by
signals at a control (gate) terminal.
Gauss's
law
A
mathematical relation between the electric flux passing through a surface and
the charge contained within that surface.
generator
In
circuit theory, an ideal voltage source or an ideal current source, whose
properties are independent of the connected circuit.
governor
A
speed regulator for a machine such as a steam engine; an early important
feedback control cybernetic system.
grid
energy storage
Any
system tied to an electrical grid that stores electrical energy at low demand
times and releases it to meet peak loads; it might be a centralized station
like a pumped-storage hydroelectric plant, or might be distributed over many
customer sites such as by the use of electric vehicle batteries.
grid-tie
inverter
A
power inverter that allows synchronization with the electrical grid for
export of energy surplus to the facility's needs.
ground
A
reference point for electrical potential; often connected to the Earth.
ground
and neutral
Protective
and circuit return conductors in a wiring system.
ground-level
power supply
A
system for providing powers for electric trams without overhead wires and
without a permanently energized third rail.
growler
A
test instrument that is used to diagnose some faults with AC motors.
GSM
The
second generation of cellular mobile phone technology, deployed since 1991 in
Europe.
Gunn
diode
A
two-terminal solid-state device that is used in microwave oscillators.
gyrotron
A
high-power vacuum tube oscillator that can produce microwave frequencies up
to hundreds of gigahertz at power levels up to megawatts.
H
H
infinity
An
optimization strategy for certain classes of control problems.
Hall
effect sensor
A
device that detects and measures magnetic field by the Hall effect voltage
induced in a current-carrying semiconductor.
harmonic
distortion
An
effect of a non-linear signal path that introduces frequencies that are
integer multiples of an input frequency.
harmonic
oscillator
An
oscillator which produces sinusoidal output, such as a simple RLC oscillator.
harmonic
A
waveform that has a frequency which is an integer multiple of another
frequency.
harmonics
Distortion
of the power line voltage due to non-linear loads such as rectifiers.
H-bridge
An
array of four controlled switches that coverts direct current to alternating
current, with peak value equal to the supply voltage.
HDTV
High
Definition Television, any television system with more than 625 scan lines.
headphone
An
audio transducer or pair of transducers arranged to be worn on (or in) the
ear.
heat
transfer
The
study of the flow of heat energy; heat transfer concerns dictate major design
features of most electrical and electronic systems.
heatsink
A
structure intended to dissipate heat from an active device into the ambient
environment.
Heaviside
step function
A
mathematical unit step function useful in the solution of certain differential
equations by the methods of operational calculus.
Helmholtz
coil
An
arrangement of coils useful for producing a uniform magnetic field within a
certain volume.
henry
The
SI unit of inductance.
Hertz
The
SI unit of frequency, equivalent to one cycle per second.
heterodyne
The
process of mixing signals of a number of frequencies to produce new
frequencies.
heterostructure
A
semiconductor device built of two or more dissimilar materials.
Hi-Fi
High
Fidelity, the set of techniques for reproduction of sounds that appear
natural in source.
high-voltage
cable
A
flexible insulated electrical conductor designed to withstand a significant
voltage; "high" voltage may be hundreds or hundreds of thousands of
volts, depending on the context.
high
voltage
Any
voltage at which safety concerns apply; in some contexts anything over 100
volts may be a high voltage; in electric power transmission, voltages over
66,000 volts are considered "high voltage".
high-pass
filter
An
electrical network that tends to pass higher frequencies and block lower
ones.
high-voltage
direct current
A
system for power transmission that uses high DC voltages for reasons of
economy or stability.
high-voltage
switchgear
Electrical
apparatus designed for control of high-voltage circuits.
Hilbert
transform
A
mathematical operation used in signal processing.
holography
The
technique of representing the image of a scene by a recording of interference
patterns of the light field.
home
appliance
Any
electrical appliance intended for use in a home.
homopolar
generator
A
generator in which current and magnetic field direction are constant as the
machien rotor revolves.
homopolar
motor
A
motor that produces torque from a current and magnetic field that does not
change direction.
horsepower
A
unit of power, equivalent to around 746 watts.
hot
wire barretter
A
current dependent resistor formed of a fine wire in an envelope, useful for
regulating current.
humidistat
A
switch that operates automatically on detecting a change in moisture content
of the air.
HVAC
High
Voltage Alternating Current; depending on context, this could be hundreds or
hundreds of thousands of volts.
HVDC
converter station
An
element of a high-voltage direct current power transmission system; each end
of the transmission line has a converter station connected to the local AC
grid.
HVDC
High
Voltage Direct Current.
hybrid
coil
A
kind of transformer used for bidirectional transmission of signals over one
pair of wires, for example, as in an analog telephone set.
hydroelectricity
The
generation of electric power from the kinetic energy of falling water.
hydropower
Power
(now nearly always electric power) generated from falling water;
hydroelectricity.
hysteresis
A
characteristic of a system where its state is history-dependent.
I
IGBT
Insulated
Gate Bipolar Transistor, a power semiconductor device that combines some of
the advantages of field-effect and bipolar transistors.
image
impedance
A
parameter used in design of electrical networks such as filters.
image
noise reduction
Any
technique used to reduce interfering effects in processing of an image.
image
processing
Electronic
recording, storage, alteration and reproduction of pictures.
impulse
response
The
response of a network to a sudden narrow pulse input.
incandescent
light bulb
A
device that uses a fine wire filament heated by an electric current to make
light...and heat.
induction
coil
An
early name for a transformer; a type of transformer for high-voltage uses.
induction
cooker
A
cooking appliance that heats pots with magnetic fields.
induction
generator
A
type of generator where the rotating field winding is excited by induction
from the stationary armature winding.
induction
motor
A
type of motor where the rotating field winding is excited by induction from
the stationary armature winding.
induction
regulator
A
kind of variable transformer that provides stepless control of the output by
changing the coupling between two coils.
inductive
coupling
Transfer
of energy between two circuits through the magnetic field that passes through
both.
inductive
output tube
A
high power, high frequency amplifier tube, in some forms capable of megawatt
pulses at hundreds of megahertz.
inductor
A
circuit component with a concentrated inductance; a coil; stores energy in a
magnetic field.
industrial
and multiphase power plugs and sockets
Electrical
fittings used to connect cables to three-phase power circuits.
industrial
automation
The
general practice of automatic control applied to industrial operations.
infinite
impulse response
A
filter which, mathematically, never gets to a zero effect of an impulse at
its input, though practically the response may become negligible after a
definite time.
information
appliance
Conceptually,
an embedded computer system with a specialized user interface designed to
simplify one task, such as e-mail or photos; a modern smart phone approaches
this concept.
information
theory
The
mathematical study of information.
information
In
one sense, the answers to uncertainties.
input/output
(I/O)
That
part of a computer system devoted to exporting and importing data, for
example, in human-readable form.
inrush
current
The
transient current that flows when first connecting a device to a power
source.
Institute
of Electrical and Electronics Engineers (IEEE)
The
American-based society for electrotechnology.
Institution
of Engineering and Technology
The
British society of electrical and electronics engineers.
instrumentation
engineering
The
profession dealing with development of measuring systems.
instrumentation
A
device that turns some physical property into a measurement.
insulation
monitoring device
A
supervisory device to detect failure of electrical insulation.
insulator
A substance
that does not permit easy flow of electric current; a fitting intended to
support a conductor.
integrated
circuit
An
interconnected array of electronic devices, factory assembled on a single
substrate.
intelligent
control
The
application of artificial intelligence techniques to process control.
intelligent
transportation system
The
application of information technology to manage some aspects of a
transportation system.
intermittent
energy source
An
energy source whose availability is not under human control; it may be
sporadically available or available on some natural schedule not coincident
with human demands; energy sources that are not dispatchable.
International
Electrotechnical Commission (IEC)
An
international standards organization devoted to electrical standards; most
countries are members.
International
Organization for Standardization
An
international organization coordinating the efforts of national technical
standards organizations.
interrupter
Any
of a series of automatically operated electromechanical switches that
periodically opened and closed a circuit.
inverter
A
system that converts direct current power to alternating current, without the
use of rotating machines, using electron devices such as mercury arc valves
or thyristors.
iron
loss
That
portion of the wasted power of a machine or transformer attributed to
hysteresis and eddy currents in the iron core.
isolated-phase
bus
A
bus where each phase is in its own grounded metal enclosure to prevent faults
from spreading from phase to phase; often used in large power plant
generators.
isolation
transformer
A
transformer especially intended to prevent leakage current from passing from
its primary circuit to the secondary circuit.
iterative
learning control
A
technique for improving the accuracy of control systems that carry out the
same sequence repeatedly.
J
j
operator
Electrical
engineering uses "j" to represent the imaginary unit "i",
to prevent confusion with the symbol for current. {\displaystyle j\times j=-1}{\displaystyle
j\times j=-1}.
Jedlik's
dynamo
An
early form of electric generator using electromagnets.
JFET
A
field effect transistor with a reverse-biased PN junction between gate and
channel.
jitter
Deviation
from the true periodicity of a periodic signal.
Joule
heating
Heating
in a conductor due to passage of current.
joule
The
SI unit of work; one joule is of the order of the energy dissipated when an
apple falls off a table top.
K
Kalman
filter
An
algorithm for estimating an unknown value from a series of approximate
measurements.
Kelvin–Stokes
theorem
A
theorem in calculus, useful in analytic solutions of problems in
electromagnetism.
Kilovolt-ampere
A
unit of apparent power.
Kirchhoff's
circuit laws
The
observation that the sum of the currents at any node of a circuit must be
zero, and the sum of the voltage differences around any loop must be zero;
often abbreviated "KCL" and "KVL" in lecture notes.
Klystron
L
LAN
Local
Area Network, an interconnection of computers over a building or small
campus.
Laplace
transform
A
mathematical operation for solution of differential equations by transforming
them to the s domain from the time domain.
laser
diode
A
semiconductor device that produces coherent laser radiation when properly energized.
leakage
inductance
The
inductance of a transformer that results from magnetic flux not linked by
both primary and secondary windings.
light-emitting
diode
A
semiconductor device that produces light or infrared or ultraviolet radiation
when properly energized.
linear
alternator
An
electrical machine that generates electric power from the relative straight
line motion of its parts.
linear
motor
An
electrical machine that generates electric force in a straight line by the
interaction of its moving parts and magnetic fields.
linear
variable differential transformer
A
transducer that produces an electrical signal proportional to the movement
between its parts.
lineman
A
specialist technician who installs outside plant wiring (overhead circuits,
power transmission lines).
Litz
wire
A
kind of stranded wire used to minimize losses in coils.
load
flow study
A
mathematical prediction of the flow of electric power in a network, based on
a model of the actual or proposed system; necessary for planning of
electrical grids.
load
following power plant
A
power plant that can economically be operated over a significant range of
output, so as to meet varying electric power demand.
load-loss
factor
A
factor for estimating energy lost in a distribution network due to load
current.
load
management
Any
strategy for altering the operation of customer loads so as to reduce peak
demand on an electrical grid.
load
profile
The
daily, weekly, or annual plot of electrical load against time.
local
positioning system
A
navigation system that doesn't cover the whole Earth; such as over a
continent, or even within a building.
LORAN
A
radio navigation system developed from a World War II military system (GEE),
used for civilian purposes till the 1980s.
Lorentz
force law
The
mathematical relation between currents in conductors and the resulting
magnetic forces between them.
lossless
data compression
Any
data compression method where the source can be reconstructed exactly; where
approximations are tolerable, lossy data compression can be used.
lossy
data compression
Any
data compression method which allows only a close approximation of the source
to be reconstructed; useful for images or music, where the human perceptual
system compensates for the errors.
loudspeaker
A
transducer that converts electrical current into sound, perceptible to more
than one listener.
low-noise
amplifier
In a
satellite radio receiving system, an amplifier placed near the antenna.
low-noise
block downconverter
In a
satellite radio receiving system, a device that amplifes and converts signlas
to a lower frequency band that will have lower losses in interconnecting
cables.
low-pass
filter
An
electric filter network that passes lower frequencies and blocks higher ones.
LTI
system theory
The
theory of systems that, over a useful range, respond proportionally to inputs
and don't change characteristics while responding.
lumen
The
SI unit of luminous flux, the energy of visible light.
lumped
parameters
Describes
an electrical network where the circuit elements are small compared to the
wavelengths of the signals passing through it.
Lyapunov
stability
A
criterion for stability of a dynamical system; if disturbances from a stable
point reduce and the system returns to that stable point, it can be said to
be Lyapunov stable.
M
machine
learning
The
set of artificial intelligence techniques for systems that can follow
examples to solve new problems.
magnet
wire
The
class of wire manufactured for winding electromagnetic coils such as in
motors or transformers.
magnetic
blowout
A
component of a switching device that uses a magnetic field to assist in
extinguishing the arc, using a permanent magnet or a coil.
magnetic
circuit
A
path through which magnetic flux passes.
magnetic
constant
The
constant that relates the strength of magnetic flux to magnetic induction in
free space.
magnetic
core memory
A
type of computer memory that stores data as magnetization in tiny rings of
ferrite material.
magnetic
field
A
field that causes magnets and currents to experience forces.
magnetic
flux density
The
amount of magnetic field per unit area; in SI units, measured in webers per
square metre.
magnetic
flux
The
magnetic field; a conductor that encloses a changing magnetic flux will have
a voltage induced in it.
magnetic
moment
The
proportionality constant that relates the twisting torque produced on an
object to the magnetic field.
magnetism
The
class of natural phenomena related to magnets and magnetic fields.
magnetization
A
property of a material that measures its response to a magnetic field.
magnetization
current
In a
transformer, that portion of the current used to support magnetic flux.
magnetostatics
The
study of stationary magnetic fields.
magnetostriction
A property
of some materials that change shape when subject to a magnetic field.
magnifying
transmitter
A
concept for a signal transmitter that used a resonant transformer to provide
a high voltage.
main
distribution frame
In a
telephone central office, the equipment that connects to subscriber circuits.
mainframe
computer
A
large centralized computer system, used for large volumes of data or
supporting multiple interactive terminals, with large input/output capacity,
generally expected to provide critical services to a business or institution
with a predictable degree of reliability.
mains
electricity
Commercial
electric power, purchased from an off-site source shared by many consumers.
Regional supplies vary in voltage, frequency, and technical standards.
mains
hum
Interference
on an audio or visual signal related to the power line frequency.
marginal
stability
Said
of a system that neither returns to its initial state when disturbed nor
diverges to some unstable condition.
marine
energy
Any
technique for extracting useful energy from tides, waves, or salinity or
temperature gradients of the ocean.
Marx
generator
A
kind of circuit for generating very high DC voltage pulses.
Maser
A
device that produces microwave energy in a similar manner to a LASER.
maximum
prospective short-circuit current
The
calculated value of current that could flow if a short circuit occurred; a
parameter for selection of circuit protection devices.
Maxwell's
equations
The
fundamental relations between electric and magnetic fields, expressed in
concise mathematical form.
mechanical
rectifier
An
electromechanical device for converting alternating current to direct
current, using sets of contacts which operate in synchronism with the AC.
mechatronics
Combinations
of mechanical systems with electronics for sensing and control.
memristor
A
hypothetical non-linear passive two-terminal electrical component relating
electric charge and magnetic flux linkage.
mercury-arc
rectifier
A
mercury-arc valve; a vacuum tube device that converts alternating current to
direct current by an arc in mercury vapor; displaced by solid state devices,
but formerly much used especially in high-voltage direct current
transmission.
mercury
vapor lamp
A
lamp that generates light from a discharge struck in mercury vapor; formerly
widely used in outdoor lighting, now replaced by lamps with better efficacy.
mesh
analysis
A
strategy for solution of the voltage distribution in some types of electrical
networks.
mesh
networking
A
topology where infrastructure nodes connect to other nodes such as to convey
information.
Metadyne
A DC
electric machine with crossed fields and two sets of brushes, used as an
amplifier or rotary DC transformer.
metal
rectifier
A
rectifier made from copper oxide or selenium; formerly widely used before
development of silicon rectifiers.
micro
combined heat and power
Equipment
that generates process or space heat and electric power, of a size useful for
a single building.
microcontroller
A
microprocessor integrated with memory and input/output circuits, useful for
embedded control.
microelectromechanical
systems
An
electromechanical system of microscopic size; they may be sensors or
actuators.
microelectronics
That
part of the field of electronics dealing with integrated circuits.
microgeneration
Small-scale
electric power production, to provide the needs of a small building or
individual consumer.
microphone
A
transducer that changes sound into electrical signals.
microprocessor
A
computer with its logical, arithmetic and control functions implemented on
one or a few integrated circuits.
microstrip
A
planar transmission line that is fabricated by printed circuit board
technology and is used for microwave-frequency signals
microstrip
antenna
A
planar antenna that is fabricated by printed circuit board technology
microwave
oven
A
heating appliance that uses microwave energy.
microwave
radio
The
subset of radio technique using wavelengths that are in the range of 3 GHz or
higher.
microwave
Part
of the radio spectrum with wavelengths shorter than 10 centimetres.
Millman's
theorem
A
theorem stating the relation between branch currents and voltages for
multiple sources in parallel.
mineral-insulated
copper-clad cable
Cable
with an outer metal cover and insulated by powdered inorganic material,
suitable for high temperature; one kind of fire resistant cable.
mobile
phone
A
handset that connects to the public switched telephone network by radio.
Modbus
A
brand name for a serial protocol for industrial control equipment
communication.
model
predictive control
A
control strategy for process systems based on a mathematical model of the
process and its disturbances.
modem
Modulator-Demodulator,
an interface between a computer system and a telephone network.
modulation
transformer
Part
of a radio transmitter used to impress modulation on one amplifying stage.
modulation
The
impression of information on a carrier wave for transmission.
monolithic
microwave integrated circuit
An
integrated circuit that operates in microwave frequencies and that can be
fabricated by printed circuit board technology.
monoscope
A
raster scan video device that generates a single fixed image for test or
identification purposes.
Moore's
law
The
observation that the number of transistors possible in an integrated circuit
doubles approximately every two years.
Morse
code
A
method of transmitting text by long and short impulses and varying delays
between them.
MOSFET
Metal
Oxide Semiconductor Field Effect Transistor, a class of transistor using a
single type of charge carrier and with a very thin insulating layer between
current channel and control gate. If you count those built into integrated
circuits, nearly all transistors are MOSFETs.
motion
control
That
part of automation that deals with accurately controlling the movements of
machines.
motor
controller
Electrical
apparatus that regulates and protects an electric motor, which may be as
simple as an on-off switch or a servo system for precision machine tools.
motor
soft starter
A
device that reduces the inrush current when an electric motor is first
connected to the power supply.
MP3
A
standard for encoding audio in digital form.
MRI
Magnetic
Resonance Imaging, a technique for examining the interiors of, for example,
medical patients, using sensitive measurements of the magnetic fields of
atomic nuclei.
multics
An
influential early time sharing computer operating system, first released in
1969.
multimeter
A
test instrument that can measure current, voltage, or resistance (though not
concurrently).
Multisim
A
brand of computer software for electronic circuit simulation.
N
nameplate
capacity
The
design power output of a generator, at specified temperature rise.
nanoinverter
Grid
tied inverters rated less than 100 watts, useful for connection of single
solar PV panels to a building AC power system.
nanotechnology
Technology
that uses devices whose principal dimensions are of the order of a few
nanometres.
National
Electric Code
The
United States national technical standard for building wiring installation.
National
Electrical Manufacturers Association (NEMA)
A US
trade association for electrical manufacturers that also develops technical
standards.
negative
feedback
Feedback
from a control system output that tends to oppose the input.
negative
resistance
A
voltage/current characteristic where increasing current leads to decreased
voltage drop across the device.
negawatt
power
In
power grid demand management, that portion of load that can be met by
conservation efforts or improved energy efficiency.
neon
sign
Strictly,
a sign that glows orange because of a discharge through neon gas; less
pedantically, any gas discharge tube formed into a sign.
neon-sign
transformer
A
high-voltage transformer with features intended to support operation of a
neon sign.
net
metering
A
metering plan that allows grid customers with their own generation to be
billed only for their net import of energy from the grid.
network
analyzer
An
analog computer system for modelling power grids; displaced now by digital
computers.
network
cable
Cables
intended for use in data interconnections, with defined performance
parameters.
network
protector
A type
of circuit breaker used to isolate a fault from a multi-transformer supply
network.
neural
networks
A
network of individual logic elements in multiple layers that emulates some of
the behavior of a biological nervous system; a technique in artificial
intelligence.
nodal
analysis
A
technique for analysis of currents in an electrical network.
node
A
defined point in an electrical network, with some potential relative to a
reference node and where currents can be summed.
noise
cancelling
A
type of microphone that preferentially picks up a near by sound source and
rejects ambient noise.
noise
reduction
The
techniques used to reduce the perception of noise in a communications path.
noisy-channel
coding theorem
A
theorem that establishes the limits of the error-free data transmission in a
noisy communication channel
nominal
impedance
The
rated impedance of an element of a circuit.
nonlinear
control
The
class of control problems relating to the control of systems that are non
linear.
nonode
Any
electron device (although practically, only vacuum tubes) with nine internal
active electrodes controlling electron flow.
Norton's
theorem
A
theorem which states that any network of current sources, voltage sources,
and resistors can be simplified to an equivalent network with only a current
source and shunt admittance; the dual of Thevenin's theorem.
notch
filter
A
filter with a narrow reject band, used to block, for example, a pilot tone
out of a communications network.
NTSC
The
US National Television Systems Committee, that developed the analog
monochrome and color television standards used for more than 60 years for
broadcasting.
nuclear
power
Production
of electric power (or propulsion power) by nuclear fission or fusion.
numerical
control
Digital
automatic control, especially of machine tools.
Nuvistor
A
type of miniature vacuum tube, developed around the same time transistors
became common in consumer electronics.
Nyquist
frequency
The
maximum frequency that a sampling system can represent accurately.
Nyquist
stability criterion
A
graphical technique for evaluating stability of a feedback system.
Nyquist–Shannon
sampling theorem
A
theorem that establishes the necessary rate to accurately sample a
band-limited signal.
O
observability
In
control theory, the measure of how well the internal state of a system
corresponds to its measurable outputs.
Oersted
The
CGS unit of magnetic field H.
ohm
The
SI unit of electrical resistance.
ohmmeter
An
instrument that measures electrical resistance.
Ohm's
law
The
mathematical relationship between voltage, current, and resistance.
one-line
diagram
A
simplified schematic diagram of a power system.
on-premises
wiring
Telecommunications
wiring owned by the customer.
open-circuit
test
A
test, of a transformer or other device, with no load connected.
open-circuit
voltage
The
voltage developed at the terminals of a device with no load connected.
open-circuit
time constant method
A
method for approximately evaluating the transfer function of an electrical
network.
operational
amplifier
A
type of amplifier with differential inputs, widely used in circuits where
feedback determines the circuit properties.
optical
fiber
A
glass or plastic fiber used to convey signals transmitted by visible light or
infrared radiation.
optimal
control
The
branch of control theory studying optimization of a control system to fit
some optimization criterion.
oscillation
A
periodic cyclical motion or disturbance.
oscilloscope
An
instrument for graphically displaying a waveform as a function of time.
Oudin
coil
An early
form of high-voltage induction coil identical in principle to a Tesla coil
except for being constructed essentially as an auto-transformer.
out
of phase
The condition
when AC generation sources are not synchronized.
overhead
line
Outside
plant run on poles or other structures; power transmission or
telecommunication wires.
oversampling
Sampling
a signal at a rate higher than required by the Nyquist criterion.
overshoot
A
transient excursion of a signal beyond its stead state value.
overvoltage
Application
of more than rated voltage to a device.
oxygen-free
copper
A
grade of copper preferred for electrical applications for its low electrical
resistance.
P
padmount
transformer
A
kind of metal enclosed distribution transformer suitable for mounting on
grade.
pantograph
A
linkage that supports the current collector of an electric locomotive.
paraformer
A
device similar to a transformer that couples energy between two circuits by
varying magnetic parameters.
parameter
estimation
In
estimation theory, the practice of assigning values to a process model so it
accurately predicts the process's behavior.
Park
transform
A
mathematical technique useful in the analysis of three-phase systems.
partial
discharge
Breakdown
of insulating gas or solid material by an electric field, but without
formation of an arc.
passivity
Incapable
of adding energy to a signal or process.
patch
cables
Short
cables with connectors, used to make connections between outlets of a patch
panel or for temporary connections to a system under test.
peak
demand
The
maximum rate at which energy is consumed from an electrical grid; may be
either an instantaneous measure or the maximum energy transferred in some
interval such as 15 minutes.
Peltier–Seebeck
effect
The thermoelectric
effect, movement of heat due to electric current flow.
pentagrid
converter
A
type of self oscillating vacuum tube used a frequency mixer in
superheterodyne receivers.
pentode
Any
five-electrode electron device, but usually a kind of vacuum tube.
permanent
magnet synchronous generator
An
AC generator that uses a permanent field magnet instead of an electromagnet.
permanent
magnet
A
magnet that retains its polarization after an external field is removed.
permeability
The
amount of magnetisation in a material resulting from an applied magnetic
field.
phase
converter
Electrical
apparatus that converts power from a system of phases to another system, for
example, converting single-phase power to three-phase.
phase-fired
controllers
An
AC power controller that adjusts the effective value of output by switching
on at a variable time phase in the AC cycle.
phase
locked loop
An
oscillator circuit that produces an output signal that is in a fixed timing
relation to a reference input.
phase
modulation
Impressing
information on a carrier wave by advancing or delaying the waveform slightly;
related to frequency modulation.
phasor
A
vector representing a signal of a given frequency in phase space.
phasor
measurement unit
A
system that measures the timing and amplitude of voltages and currents on an
electrical grid, synchronized over a wide geographic area; the resulting
measurements can be used to manage power flow on the grid.
phonograph
A
record player, a device that converts the mechanical movements of a stylus in
a disk or cylinder recording groove into sound.
photocell
A
light sensor that produces or alters a voltage when light is present.
photodetector
Any
device that detects visible light.
photodiode
A
two-terminal device whose terminal voltage or current changes in response to
light.
photometer
An
instrument that measures light.
photonics
The
technology of conveying information through light or infrared radiation.
photoresistor
A
resistor whose resistance varies when light strikes it.
phototransistor
A
transistor sensitive to light.
PID
controller
A
process control system that has proportional, integral and derivative terms
in its response to errors between measured value and setpoint.
piezoelectric
effect
Production
of a voltage in response to mechanical pressure or mechanical deformation.
piezoelectric
motor
A
type of motor that uses piezoelectric elements to generate force.
PIN
diode
A
multilayer semiconductor diode with a thin region of intrinsic material between
its p-doped and n-doped regions.
planar
graph
In
network theory, a set of nodes and interconnecting lines that can be given in
one plane without crossing lines.
plasma
A state
of matter where electric charges are free to move.
plenum
cable
A fire-resistant
data communications cable that is permitted to be installed in the air
handling spaces of a modern building.
plug-in
hybrid
A
hybrid electric vehicle that can be recharged from grid power as well as its
own engine/generator.
P-N
junction
The
boundary between two differently doped regions of a semiconductor.
polarization
density
A
measure of the increase of the intensity of an electric field over that in
free space, owing to the separation of atomic-scale electric dipoles.
polyphase
coil
A
coil intended for connection to a polyphase power supply.
polyphase
system
An
alternating current power transmission system using three or more wires, each
of which carries a current that is displaced in time with respect to the
others.
Pontryagin's
minimum principle
A
mathematical principle used in the theory of optimal control.
port
Any
place at which energy can be observed to enter or leave a system.
positive
feedback
Feedback
from the output of a system that tends to increase the effect of any input;
if overdone, leads to instability.
potential
difference
A
voltage difference, the amount of work required to bring a test charge from
one point to another divided by charge magnitude.
potentiometer
A
three-terminal variable resistor, which can be configured as an adjustable
voltage divider.
power
BJT
A
bipolar junction transistor that can be used in circuits handling a watt or
more of power.
power
cable
Flexible
insulated electrical conductors used to transmit electric power.
power
conditioner
Any
system intended to alter some property of the bulk power supply to improve it
for some application; such as filters, surge suppressors, voltage regulators,
uninterruptible power supplies, and many others.
power
consumption
The
rate at which a device consumes energy.
power
converter
Apparatus
intended to convert electric power to another form of electric power, such as
conversion between AC and DC or changing frequency or phase number.
power
distribution
That
portion of an electrical grid between the substation or bulk supply and the
end consumer.
power
electronics
The
class of electronic devices handling power greater than a watt.
power
engineering
That
part of electrical engineering that deals with the generation, distribution
and consumption of electrical power.
power-factor
correction
Apparatus
intended to bring the power factor of some load closer to 1.
power
factor
The
ratio of apparent power flowing to a load divided by the real power.
power-flow
study
A
load flow study; mathematical prediction of the magnitudes and direction of
power flow in an existing or planned power grid; an essential part of grid
management.
power
generation
The
practice of converting other energy sources to electric power.
power
grid
An
interconnected network of generators, transmission lines, and apparatus for
reliable and economic transmission and utilization of electric power.
power
inverter
A DC
to AC power converter.
power-line
communication
The
impression of carrier waves on a power line circuit for signalling purposes.
power
MOSFET
A
metal oxide semiconductor field effect transistor suitable for use in
circuits handling more than a watt of power.
power
plant
A
facility that converts other energy forms into electric power.
power
rating
The
nominal power that an apparatus or machine can handle, with specified or
customary temperature rise and life expectancy.
power
quality
Conformance
of an electrical power supply with its specifications.
power
storage
A
facility that changes electric power into some form that can be stored and
usefully reconverted back to electric power, for example, pumped storage or
battery systems.
power
supply
A
subsystem of a computer or other electronic device that turns electric power
from a wall plug or batteries into a form suitable for use by the system.
power-system
automation
The
implementation of power-operated switching and control that allows automatic
operation of power system elements, instead of manual operation.
power-system
protection
The
technology of limiting the spread of failures of a power system to a minimum,
and of preventing permanent damage to apparatus or conductors by such faults.
printed
circuit board
An
etched wiring assembly for interconnection of electronic components.
printer
A
device that makes permanent human readable images and text from computer
data.
process
control
The
field of study of automatic control of processes.
programmable
logic controller
A
computer system designed to be rugged enough for industrial use and with a
programming environment highly tuned to the domain of industrial control
problems.
programming
language
A
formalism for human-readable instructions to a computer.
protective
relay
An
electromechanical or electronic device that detects faults on a power system
and can signal circuit breakers to operate.
proximity
effect
The
increase in circuit resistance when the magnetic fields of multiple AC
currents interact.
pulse
transformer
A
transformer designed to create or transmit pulses.
pulse-width
modulation
Transmission
of information by varying the duration of pulses,or, varying the average
output voltage of a power converter by varying the duration of pulses.
pulse-amplitude
modulation (PAM)
Transmission
of information by varying the magnitude of a stream of pulses of fixed
frequency.
pulse-code
modulation
Any
system for conveying analog information by altering some property of a stream
of pulses.
pumped-storage
hydroelectricity
A
grid energy storage system that pumps water uphill for later use by a
hydroelectric generator plant.
push
switch
A
device that closes or opens an electrical circuit when pushed.
push–pull
converter
A
converter with two sets of primary switching elements so that the transformer
primary voltage can be reversed on each cycle.
Q
quadrature
booster
A
phase shifting transformer that can inject voltages that are time delayed
with respect to the input voltage.
quality
factor
In a
resonant circuit, the ratio of stored energy to energy dissipated on each
cycle of oscillation.
quantization
Analog
to digital conversion, changing a continuously varying analog signal to
discrete digital numbers.
R
radar
cross section
The
effective reflecting area of a radar target, which varies with frequency,
geometry, and surface composition.
radar
Radio
Detection and Ranging, the techniques for observing the speed and position of
objects by reflected radio waves.
radio
frequency
Electromagnetic
waves with frequencies less than that of infrared radiation; commercially
important radio frequencies range from tens of kilohertz up to around a
terahertz.
radio
transmitter
Apparatus
designed to generate radio frequency electric current, which, connected to an
antenna, can radiate energy through space.
radio
The
technology of radio frequency devices.
railway
electrification system
A
set of standardized methods for applying electric power in railway traction.
Rankine
cycle
A
thermodynamic cycle, an idealized version of the operation cycle of a steam
turbine.
reactive
power
That
component of apparent power flow due to the return to the source of energy
stored in a load's electric or magnetic fields, that does no useful work at
the load.
real-time
operating system
A
computer operating system that ensures responses with a bounded time to
events such as in a controlled process.
receiver
The
apparatus that takes radio-frequency currents induced in an antenna and turns
them into useful signals.
rechargeable
battery
A
secondary battery; a battery that can have a useful portion of its capacity
restored by connection to a supply of electric current.
reciprocity
(electrical networks)
A
theorem that states that the current injected into one point in a network
will produce a voltage at a second point that is identical to the voltage produced
at the first point by injection of the same current at the first point
reciprocity
(electromagnetism)
An
observation that electric currents and electric fields can be analyzed from
either point of view as regards the source of the energy in the system; for
example, in radio, a good transmitting antenna is generally also a good
receiving antenna.
record
player
A
phonograph; a device that turns the variations in a disk or cylinder
recording groove into sound.
rectifier
A device
that converts alternating current (which periodically reverses) to direct
current that flows in only one direction; may be a solid-state, vacuum tube
or electromechanical device.
rectiformer
A
combination of a transformer and a rectifier, used in electrochemical processes
or supply of electrostatic precipitators.
recursive
least squares filter
An
algorithm for a digital filter system.
Reed
switch
An
electrical switch made of two thin strips of ferromagnetic metal, which touch
when subject to a magnetic field.
regenerative
braking
A
braking scheme that returns energy to the source.
regenerative
circuit
A
circuit that employs positive feedback; can be an amplifier or an oscillator.
relaxation
oscillator
An
oscillator that relies on an active device periodically changing state; such
oscillators usually produce a square-wave or sawtooth waveform, different
from the approximately sinusoidal waveshape of a harmonic oscillator.
relay
An
electrically operated switch.
reluctance
motor
A
type of electric motor that induces non-permanent magnetic poles on the
ferromagnetic rotor, relying on varying magnetic reluctance; the rotor
carries no windings.
remanence
That
portion of the applied magnetic field that the material retains when the
external field is removed.
remote
racking system
A
system for inserting circuit breakers into switchgear that allows the
operator to stay at a safe distance from any possible arc hazard.
remote
sensing
Acquisition
of measurements of an object without contact, for example, measuring soil
moisture by radar from an aircraft.
renewable
electricity
Electric
power derived from primary energy sources that replenish on a rapid scale or
that are not appreciably diminished by human exploitation.
renewable
energy payments
Any
incentive program to improve the economic return of a renewable energy
project.
renewable
energy policy
Government
plans to displace fossil fuels with renewable sources.
repeating
coil
An
old name for a transformer, especially used in telephone circuits.
repowering
Refurbishing
the equipment of a power plant, with a view to improved efficiency or life
span.
repulsion
motor
A
wound rotor induction motor using a pair of short-circuited brushes on a
commutator.
resettable
fuse
A
circuit protective device that opens on excess current, and then, on cooling
off, restores the circuit automatically.
residual
current circuit breaker
A
circuit breaker that detects unbalance of phase currents due to ground fault.
resistive
circuit
A
circuit containing resistive elements only, no capacitors or inductors.
resistivity
The
property of a material that impedes current flow.
resistor
A
circuit component that primarily has resistance.
resolver
A
transformer-like rotary transducer that measures rotation as an analog value.
resonant
cavity
An
opening that when excited by an electron stream or other means, oscillates at
a particular frequency.
resonant
inductive coupling
A
form of energy transfer between two physically close tuned circuits.
return
loss
A
measure of the power loss due to a signal reflection by a discontinuity in a
transmission line or an optical fiber.
RF
connector
An
electrical fitting used to connect cables carrying radio frequency currents.
RF
engineering
The
profession that deals with application of radio frequency energy to useful
ends.
rheoscope
Obsolete
name for an ammeter; now an instrument for measuring fluid viscosity.
rheostat
Obsolete
name for a two terminal variable resistor, usually with a rotating shaft to
allow manual or motor driven adjustment.
right-hand
rule
A
mnemonic device for remembering the definitions of the directions of current
and magnetic field in generators.
ripple
A
periodic variation in the amplitude of a DC signal, such as found in a power
supply with partly effective filtering.
RLC
circuit
A
circuit that has only resistors, inductors, and capacitors in it.
robotics
The
field of automation that deals with manipulators, especially those that mimic
human appendages.
robust
control
A
static control algorithm that can produce acceptable performance over an
anticipated useful range of process disturbances.
Rogowski
coil
A
current sensing coil that produces a voltage proportional to the rate of
change of current; by integration, this can be turned into a measure of current.
root
locus
A
graphical method for analyzing the properties of a transfer function as some
parameter is varied.
root
mean square
The
root mean square value of a waveform is the DC value that corresponds to
equivalent heating value.
rotary
converter
An
electric machine that converts electric power between two forms, say, AC and
DC or single-phase and three phase, or between two different frequencies of
AC (the latter two can be performed by the same machine).
rotary
encoder
A
transducer that converts rotation of a shaft to a measurement.
rotary
switch
A
switch operated manually or electrically with a rotary motion of the
contacts.
rotary
transformer
A
transformer used to couple electric signals or power between rotating parts.
rotary
variable differential transformer
A
transformer-like transducer that measures rotation as an analog value.
rotor
That
part of an electrical machine that rotates. Not necessarily the armature.
Routh–Hurwitz
stability criterion
A
criterion for predicting the stability of a system with a given transfer
function.
S
Sallen–Key
filter
A
family of active filters with a second-order characteristic, first described
in 1955.
sample
and hold
A
circuit that takes a sample of a changing analog value and holds onto it
until the value can be processed by some other stage.
sampling
The
process of taking a continually varying signal and turning it into a stream
of numbers taken at regular intervals.
sampling
frequency
The
rate at which an analog value is sampled.
satellite
A
natural or artificial object that circles another, bound only by gravity.
satellite
radio
A
radio broadcasting service using signals from an Earth satellite to customer
receivers.
saturation
That
point in the magnetization of a substance where most magnetic domains are
aligned with the external field; further increase of the magnetizing force
(H) gives only small increase in the magnetization (B).
SCADA
Supervisory
Control and Data Acquisition, management of geographically distributed automation
systems such as for an electrical grid.
scattering
parameters
A
matrix that describes the electrical behavior of linear electrical networks,
most prominently the distributed microwave systems.
Schmitt
trigger
A
circuit that behaves like a snap-action switch, suddenly changing state as an
analog signal increases; displays hysteresis.
Schottky
diode
A
diode that relies on the junction between a semiconductor and a metal.
Scott-T
transformer
A
transformer connection for balanced interconnection of a two-phase system and
a three-phase system.
s-domain
A Laplace
transform converts a function from the time domain to the "complex
frequency" s-domain; making certain mathematical operations much simpler
to evaluate.
SDTV
"Standard
definition television" – what descriptions of HDTV call any system with
625 scan lines or less.
segmentation
A
step in digital image processing that groups picture elements of an image
that notionally represent some physically significant property of the imaged
objects.
selenium
rectifiers
One
type of metal rectifier, though selenium is considered a
"metalloid" – formerly much used but now replaced by silicon
semiconductors.
semiconductor
A
substance with electrical conductivity between that of insulators and conductors;
displays a negative temperature coefficient of resistance, and is also
sensitive to light. The conductivity of semiconductors can readily be altered
by trace amounts of other substances, leading to devices that are the
foundation of nearly all modern electronics.
semiconductor
device
A
device that relies on substances with electrical conductivity between that of
insulators and conductors; the controllable conductivity of these materials
makes most of modern electronics possible.
semiconductor
fabrication
The
process of turning the raw source of silicon into transistors and integrated
circuits.
sensor
A
device or system that converts some physical event into an electronic signal,
for further use in measurement or control.
serial
communication
Transmission
of data as a single series of bits over a communication path.
series
and parallel circuits
Electrical
circuits where current passes through multiple elements either one after the
other, or side by side, like the rungs of a ladder, or both.
shaded-pole
motor
An
alternating current single phase motor that produces a rotating magnetic
field by a turn of wire around part of a field pole.
shaft
voltage
An
objectionable stray voltage that appears on the rotating part of an
electrical machine; very deleterious to supporting bearings.
shielded
twisted pair
Two
wires, wrapped around each other and covered with a flexible shield
conductor; intended to reject external interference.
short-circuit
test
A
test of machines or apparatus where the load terminals are directly
connected; usually done at reduced power to prevent damage, but destructive
short circuit testing may be carried out on circuit protective devices.
short
circuit
A
path in a circuit that has negligible resistance; often un-intended, a fault.
shunt
A
small value resistor connected around a metering element to carry most of the
current; only a small part passes through the meter.
siemens
A
reciprocal ohm, the SI unit of conductance. The former Siemens mercury unit
was a unit of resistance.
signal
Some
intentional modification of a physical communication path that is intended to
convey information from one place to another.
signal
processing
The
technology to extract information from signals.
signal
strength
A
measure of the usable power of a physical signal.
signal-flow
graph
A
formal mathematical treatment of the representation of signal flow through a
system, such as an analog computer or a radio receiver.
signal-to-noise
ratio
A
measure of the power contained in the useful part of the signal, to the power
contained in noise. Often measured in decibels; for example, in sound
reproduction a 40 or 50 decibel signal to noise ratio would be broadcast
quality, whereas a 10 decibel ratio would represent very difficult operating
conditions for a voice radio system.
silicon
controlled rectifier
A
four layer semiconductor switching device that can stand off an applied
voltage until triggered by an electrical pulse on a control lead.
Silicon
Valley
Initially,
a region of California known for a large number of electronics technology
firms.
sine
wave
The
waveform of the mathematical sine function; a fundamental wave shape, free of
harmonics.
single-phase
electric power
An
alternating current power system using only two wires, where peak voltages in
each wire occur at the same time.
single-sideband
modulation
A
radio carrier modulation system where redundant frequencies of one duplicate
side band are filtered out along with the carrier, to save transmitter power.
skin
effect
The
tendency of alternating current to flow at the periphery of a conductor;
significant for large conductors at power frequencies, and increasingly
significant as the frequency increases.
sliding
mode control
A
control strategy for a nonlinear system that uses discontinuous control
signals.
slip
ring
A
sliding continuous electrical contact between a machine's rotating parts and
the fixed external circuit.
small
signal model
An
analytical tool for systems that show significant non-linearity for large signal
excursions.
smart
grid
The
application of information technology to improve performance of the
electrical grid.
Smith
chart
A
graphical tool for display of the impedance of devices at varying
frequencies, and for solution of problems of impedance matching in radio
frequency design.
software
engineering
The
profession of designing software systems to meet specified performance
requirements.
software
The
set of instructions and data that direct a computer system.
solar
cell
A
photovoltaic cell, used to produce power from sunlight.
solar
energy
Useful
energy extracted by some means from sunlight.
solar
micro-inverter
An
inverter suitable for use with a single solar panel.
soldering
The
process of joining metals using a low melting point filler metal; a critical
process in the assembly of most electronic devices.
solenoid
A
coil of wire used to create a magnetic field; often a device with a
ferromagnetic plunger that moves when the coil is energized.
solid
state
Electronics
that relies on current flow through crystalline lattices.
solid
state physics
That
branch of physics that studies arrangements of atoms in fixed arrays.
sound
recording
The
technology of recording sound for later reporduction.
space
vector modulation
A
control strategy for variable frequency motor drives.
spark
spread
The
difference between the revenue from selling a unit of electricity and the
cost of the fuel used to make it.
spark-gap
transmitter
A
former type of radio transmitter that generated radio frequency current by
exciting resonance of a tuned system with an electric spark, used almost
entirely for transmission of Morse code.
spectrum
analyzer
An
instrument that graphically displays the amplitude of signals in a narrow
bandwidth across a frequency band.
speech
processing
The
techniques for improving the intelligibility of human speech in a
communications system.
SPICE
A
set of computer programs for modelling the behavior of electronic circuits.
split
phase distribution
A
type of distribution system that uses a center tapped transformer to provide
two voltages to a building wiring system.
split
phase motor
A
type of single phase motor that uses a resistor, inductor, or capacitor and
two windings to obtain a rotating magnetic field.
square
wave
A
waveform that spends equal times at the positive and negative peak values
with rapid transitions between them.
stability
theory
The
systematic study of control systems that deals with their response to
disturbances.
stable
polynomial
That
class of polynomials representing the transfer functions of stable control
systems.
stacking
factor
A
measure of the efficiency of filling the space of a machine core or winding;
the proportion of active material in any given unit cross section.
standing
wave ratio
A
measure of impedance mismatch for transmission lines in microwave
engineering; the ratio of peak amplitude of a standing wave to its minimum.
star-mesh
transform
A
mathematical technique used in circuit analysis.
state
observer
In
control theory, that which discovers and reports the internal state of a
controlled system.
state
space representation
A
mathematical technique to represent the internal state of a controlled system
as a vector in a Euclidean space.
static
VAR compensator
A
system that adjusts reactive power flow without moving parts, such as an
electronically controlled capacitor bank.
stator
That
part of a rotating electrical machine that remains stationary.
steady-state
The
condition of a control system where changes due to some disturbance are no
longer occurring at a significant rate.
steam
turbine
A
rotating machine that converts the energy of expanding steam to mechanical
power through its interactions with sets of moving and stationary blades.
step
response
The
behavior of a control system in response to an abrupt change of input.
stepper
motor
An
electric motor that moves its shafts in discrete steps as different poles are
energized.
stereophonic
sound
Sound
reproduction systems intended to reproduce sound emanating from more than one
direction.
Stokes'
theorem
A
theorem about integration of three-dimensional functions, much used in
analysis of electric fields.
storage
tube
A
type of cathode ray tube, used for storing images or data.
stray
capacitance
A
property of every conductor, when considered as a non-ideality.
structured
cabling
A
system for design of the telephone and data communications cable systems of a
building.
submarine
communications cable
A
telephone or telegraph cable that is substantially under water.
sulfur
hexafluoride circuit breaker
A
kind of automatic circuit protection switch that breaks current in an
atmosphere of pressurized sulfur hexafluoride gas to extinguish the arc.
super
grid
A
wide area power transmission network that allows interchange over continental
distances.
supercomputer
A
computer with a substantially higher level of performance than a general
purpose machine; especially adapted for high intensity calculation on large
data sets.
superconducting
electric machine
An
experimental type of generator or motor that has part of its electric
circuits in the superconducting state.
superconductivity
The
loss of all electrical resistance at inconveniently low temperatures.
superheterodyne
receiver
A
radio receiver that changes incoming frequencies to a fixed intermediate
frequency for processing.
superposition
theorem
The
useful property of a system where the response to the sum is the sum of the
responses.
surge
arrester
A
device intended to absorb brief transient overvoltages to protect machines or
apparatus.
surge
protection
The
measures taken to protect machines and apparatus from transient overvoltages.
switch
An
electrical device that opens and closes a circuit; it may be manually
operated, automatically operated by some other electrical circuit, or
operated by the change in some physical condition such as flow, level, or
temperature.
switched
reluctance motor
A
motor that relies on induced magnetism in salient poles, instead of a rotor
winding.
switched-mode
power supply
A
power converter that regulates voltage by adjusting the time duration of a
switching device; this gives reduced heat dissipation compared to an
equivalent linear regulator device.
switchgear
An
array of switches, circuit breakers and related apparatus for power
distribution.
symbolic
circuit analysis
Analytical
circuit analysis in terms of expressions with variables, instead of numerical
solutions for a particular case of values.
symmetrical
components
A
technique to simplify analysis of unbalanced polyphase systems.
synchro
A
synchromotor, a class of electrical motors that follows the rotation of a
source.
synchronization
Aligning
the timing of two or more sources, such as synchronizing a generator before
connecting it to a grid.
synchronous
circuit
A
logic circuit where internal state changes only propagate in step with a
master clock signal.
synchronous
motor
A
motor that rotates at a speed exactly related to the supply frequency.
synchronous
rectification
A
converter from alternating to direct current, where switching devices
actively are operated in step with the positive and negative excursions of
the supply.
synchroscope
An
instrument used to bring an alternating current generator into
synchronization with a grid, that uses a moving pointer or set of lamps.
system
identification
The
technique of development of a mathematical model of a controlled system;
model identification.
system
on a chip
An
integrated circuit that combines multiple significant subsytems of a product
on one die, for example, analog signal processing and digital controls.
system
on module
A
packaging of significant functions of a complete product in a form that can
be used in more than one product.
T
tachometer
An
instrument that measures rotational speed (or angular velocity).
tap
A
connection to a winding at some point between the ends, used to adjust
voltage.
tap
changer
A
switch that selects which transformer tap is connected to an external
circuit; may be manually operated, or power operated; some types can be
operated under load for voltage regulation purposes.
technical
drawing
Drawings
intended to convey information for construction, operation or maintenance of
a system or equipment.
telecommunication
The
field that deals with transmission of information over distances longer than
can be covered by an unaided human.
Telecommunications
Industry Association
A US
based trade association that develops technical standards.
telegraph
A
system for transmitting text messages, by wire or other means.
telegrapher's
equations
Coupled
linear partial differential equations that relate the voltage and current on
a transmission line.
telephone
balance unit
A
balun, a transformer used to convert between balanced and unbalanced lines, as
used in telephone circuits.
telephone
line
Outside
plant that connects a central office to subscriber equipment.
telephone
Transmission
of voice by electrical means.
television
Transmission
of moving images by electrical means.
Tellegen's
theorem
A
theorem relating to branch currents in an electrical network.
tesla
The
SI unit of magnetic flux density.
Tesla
coil
A
kind of resonant transformer capable of very high voltages; almost identical
to an Oudin coil except that it has separately wound primary and secondary.
tetrode
An
electron device, nearly always a vacuum tube, with four internal active
electrodes.
thermionic
emission
Emission
of electrons from a hot surface; the Edison Effect was an early instance of
description of this phenomenon.
thermistor
A
temperature sensitive resistor with a large, somewhat variable, temperature
coefficient of resistance.
thermocouple
A
junction of two dissimilar metals that generates voltage when at a
temperature above absolute zero.
thermoelectric
effect
The
conversion between heat flow and current flow, and the reverse.
thermostat
A
temperature sensing switch.
Thévenin
theorem
A
theorem which states that any network of current sources, voltage sources and
resistors can be simplified to an equivalent network with only a voltage
source and series impedance; the dual of Norton's Theorem.
third
rail
An
energized conductor in the track bed, using a sliding contact to transfer
power to an electric train.
three-phase
AC railway electrification
Application
of three-phase power to railways.
three-phase
electric power
Electric
power transmission using three conductors carrying currents which peak at
separate evenly spaced times in each cycle; widely used for motors.
thyristor
A
four layer semiconductor device that stands off applied voltage until
triggered.
thyristor
drive
A
variable speed drive, usually with direct current motors, using thyristors as
the switching elements.
tidal
power
Extraction
of useful energy, usually as electric power, from the tidal rise and fall of
water.
time
sharing
A
system whereby multiple human users of a computer can proceed as if they had
sole use, while the computer processes each user's software in round-robin
fashion.
time-invariant
system
A
systems whose characteristics don't vary significantly with time.
topology
The
shape of an electrical network, independent of its size or values.
toroidal
inductors and transformers
Magnetic
coils wound around a ring of ferromagnetic material.
total
harmonic distortion (THD)
A
measure of the magnitude of harmonically-related frequency components a
signal processing stage adds.
traction
battery
A
battery used to store energy for propelling a wheeled electric vehicle.
traction
current
Power
supply for wheeled electric vehicles.
traction
motor
An
electric motor for a wheeled vehicle.
traction
substation
A
substation that supplies current to a railway, subway or similar electric
wheeled transit.
transatlantic
communications cable
A
cable for voice or data running under the Atlantic Ocean.
transceiver
Apparatus
that combines a receiver and transmitter.
transconductance
transducer
An
instrument that converts a physical quantity into another electrical or
physical quantity.
transfer
function
The
mathematical relation between input and output, usually expressed in terms of
frequency or complex frequency (s-domain).
transformer
oil testing
Examination
of transformer oil for its insulating strength, dissolved moisture and other
properties, to ensure it is still suitable for use.
transformer
oil
A
hydrocarbon liquid that cools and insulates transformers and other types of
electrical apparatus.
transformer
A
static arrangement of conductors and possibly magnetic materials, that
transfers energy by electromagnetic induction.
transformerboard
A
kind of insulating paperboard used for internal structures of large oil
filled power transformers.
transient
response
The
short-time response of a system to a disturbance.
Transil
A
brand of transient voltage suppression diode.
transistor
A
three terminal solid state device used as an amplifier or switch.
transmission
The
process of getting a signal from one point to another.
transmission
line
An
arrangement of conductors for movement of electric power; used from DC to
upper radio frequencies.
transmission
system operator
A
corporation that runs the transmission system between sources of power and
distribution substations.
transmission
tower
A
structure for support of overhead transmission wires.
transmitter
Apparatus
that prepares a signal for emission into some medium, such as a radio
transmitter or a sonar transmitter.
traveling-wave
tube
trembler
coil
A
kind of high-voltage coil that includes an interrupting mechanism, formerly
used in automobile ignition systems.
TRIAC
A
variation of the thyristor that can pass bidrectional (ac) current.
triangle
wave
A
waveform composed of straight line segments that extend from minus peak to
plus peak.
trigger
transformer
A
transformer that generates a pulse to initiate some other device, such as a
thyristor or a flash tube.
triode
An
electron device, nearly always a vacuum tube, that has three active
electrodes.
trolley
pole
A
support for a current collector on a vehicle.
trolleybus
Strictly,
a passenger vehicle that collects motive electric power from a pair of overhead
conductors.
tuned
circuit
A
circuit that displays a peak response at some frequency.
twisted
pair
Two
wires twisted around each other, possibly covered with an overall sheath;
this configuration rejects some kinds of interference.
two-phase
electric power
An
electric power system using two sets of alternating currents, displaced in
time by a quarter period.
two-port
network
A
network that has two places to exchange energy with its surroundings.
two-sided
Laplace transform
A
variant of the Laplace transform that simplifies certain operations.
U
ubiquitous
computing
A
scenario where computer science is made to appear everywhere.
ultrasonic
motor
A
motor that relies on a component oscillating at an ultrasonic frequency.
ultrasonics
Term
for the field of study pertaining to pressure oscillations in air or other
media that are above the range of human hearing.
ultrasound
Sound
having a frequency above the range of normal human hearing. A portmanteau of
the former description of 'ultrasonic sound'
undersampling
Sampling
a signal at less than the Nyquist rate; can produce alias frequencies or
other artifacts.
unijunction
transistor
A
three terminal semiconductor device with a definite switching characteristic
and only one PN junction.
unipolar
motor
A
heteropolar motor; all currents in this design flow in only one direction.
unshielded
twisted pair
Two
wires wrapped around each other, but without a conductive cover.
upsampling
Sampling
at greater than the Nyquist rate, which makes filter design easier.
utility
frequency
60
or 50 cycles per second, used for electric power.
utility
pole
A
columnar structure that carries wires for electrical power distribution,
cable television, telephone or similar services.
V
vacuum
capacitor
A
capacitor using vacuum as its dielectric; useful at high voltages or radio
frequency.
vacuum
tube
An
electron device that relies on flow of electrons through a vacuum or
low-pressure gas; a valve. The first electronic devices that could amplify.
valve
A
switching element (mercury arc, thyristor, or other device) in a high-voltage
direct current converter; each phase contains two or more valves, which may
be series-connected for higher voltages. Or, a vacuum tube.
variable
capacitor
A
capacitor whose value can be changed, by rotating a shaft, squeezing a plate
or by an electrical signal; for example, as used to tune a radio.
variable-frequency
drive
A
power converter that varies the speed of an AC motor by changing its
frequency; usually, today, a solid-state device.
Variac
One
brand of adjustable transformer, that can essentially continuously vary the
ratio between primary and secondary.
varicap
Variable
capacitor – usually a diode whose reverse-biased junction capacitance can be
varied by applied voltage.
varistor
Variable
resistor – a protective device that has a high resistance at low voltage but
momentarily switches to lower resistance on exposure to a high voltage.
vector
control
A
strategy for control of variable-speed motor drives.
vector
group
The
classification of the connections of a polyphase transformer.
vehicle-to-grid
A
concept to use electric vehicle batteries as a form of grid energy storage.
vehicular
automation
Automatic
systems to assist, or replace, the driver of a vehicle.
Versorium
An
antique version of an electroscope.
vibrator
An
electromechanical interrupter, part of a DC-to-AC converter in a
battery-operated vacuum tube radio, or similar application. Some had
additional contacts to act as a synchronous rectifier.
video
camera tube
A
family of vacuum tube devices used to pick up images and transmit them
electronically.
video
processing
The
techniques used to enhance video images.
virtual
instrumentation
A
software-intensive measuring system that can be programmed to emulate any of
a number of conventional measuring instruments, or some combination of
measuring functions.
virtual
power plant
A
strategy for managing a collection of disparate power sources, interconnected
with a communications network, as if they were a single centralized power
plant.
VLSI
Very
Large Scale Integration, the ability to put hundreds of thousands of
interconnected transistors onto one chip.
volt
The
SI unit of electrical potential difference; moving a charge of one coulomb
through a potential of one volt transfers one joule of energy.
voltage
The
electric potential difference between two points.
voltage
compensation
Generally,
adjustment of a voltage source to compensate for voltage drop; techniques
differ widely between a computer power supply and a long-distance power line.
voltage-controlled
amplifier
An
amplifier that has its gain controlled by a voltage signal.
voltage
controller
A
device that adjusts the (effective) voltage to a load.
voltage
converter
Any
device that changes electric power at one voltage to power at a second; a
transformer is a common example of an AC voltage converter.
voltage
division
A
circuit that produces an output voltage that is some, perhaps adjustable,
fraction of the input voltage.
voltage
doubler
A
rectifier circuit that can product an output DC voltage of nearly twice the
input AC voltage.
voltage
regulation
A
measure of how a source maintains its output voltage for varying load.
voltage
regulator
A
system that automatically stabilizes the voltage at which power is supplied
to a downstream system.
voltage
source
In
circuit theory, a hypothetical element that maintains a specified voltage
between its terminals independent of the current through it.
voltage
spike
A
transient electrical voltage higher than normal appearing on an electrical
supply.
voltage-to-current
converter
A
circuit that produces an output current proportional to an input voltage.
volt-ampere
The
unit of apparent power in an AC circuit.
voltmeter
An
instrument for measuring potential difference.
W
war
of the currents
The
late 19th century commercial dispute on whether AC or DC was the best system
for power distribution.
Ward
Leonard control
A
speed control system for DC machines using an interconnected generator and
motor.
watt
The
SI unit of power, work done per unit time.
wattmeter
An
instrument that measures electrical power.
waveguide
A
tubular structure that guides electromagnetic waves, much used at microwave
frequencies; an optical fiber is a kind of optical waveguide.
weber
The
SI unit of magnetic flux.
wet
transformer
In
telephone systems, a matching transformer that can operate while carrying a
substantial DC "wetting" current.
Wien
bridge oscillator
A
type of electronic oscillator that generates sine waves and is based on a
bridge circuit.
Wiener
filter
A
class of filters used in signal processing, used to fit an estimate to noisy
signal data.
Williams
tube
A
cathode ray vacuum tube used as an early form of computer memory.
wind
farm
An
array of two or more wind turbines, usually sharing a substation.
wind
power
Generation
of electricity (sometimes mechanical power) from wind.
wind
turbine
A
rotating machine that extracts energy from wind.
wire
A
strand of metal much, much, longer than it is wide; a conductor, often coated
with insulation.
wireless
network
Data
network relying on radio for the connection to end device; may span a
building or a larger area.
wireless
telegraphy
Transmission
of text by radio; usually implies Morse or radio-teletype.
X
X-ray
Electromagnetic
radiation with wavelengths shorter than ten nanometres. Strictly: radiation
that is produced in the electron shell of atoms.
X-ray
lithography
A
developing technique for production of very high density structures in
integrated circuits.
Y
Yagi
antenna
A
type of radio antenna using a feeder element, one or more parasitic reflector
elements, and one or more director parasitic elements to provide a directional
characteristic; the classic home TV rooftop antenna was usually a Yagi
antenna .
Y-delta
transform
A
mathematical technique in circuit analysis to simplify a circuit.
Z
Zener
diode
Nickname
for "voltage regulator diodes" which may rely either on the Zener
effect or avalanch breakdown to maintain a roughly constant voltage; the two
effects have opposite temperature coefficients of voltage.
zigzag
transformer
A
multiwinding three phase transformer, sometimes used for grounding.
Z-transform
A
mathematical operation that converts a set of evenly spaced measurements of
an analog signal into a series of frequency components.
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