Home > World of Electricity - Glossary
World of Electricity - Glossary
A
Glossary of Common Electrical Terminology
A
Absolute
Zero: -459.67°F or -273.15°C or 0 Kelvin. The
temperature where thermal energy is at minimum.
Actuator:
The mechanism of a switch which operates the contacts.
Alternating
Current: (AC); Electrical current that changes (or
alternates) in magnitude and direction of the current at regular
intervals.
American
National Standards Institute:
ANSI
Amp:
(ampere)The basic unit of current in an electrical
circuit. One ampere is the rate of flow of electric current when one
coulomb of charge flows past a point in the circuit in one second.
Symbolically characterized by the letter "I" and sometimes
"A" when used in formulas.
Ampere:
A unit of electrical current named after French
physicist André Marie Ampère (1775-1836), also see
"amp".
Amplifier:
An electrical circuit that increases the power, voltage
or current of an applied signal.
Anode:
A positive (+) electrode. The point where electrons
exit from a device to the external electric circuit.
AWG:
"American Wire Gauge" system used to determine wire size.
B
Beta:
The current that is gained by a transistor when it is
connected in a common emitter circuit.
Break:
The act of the opening of an electrical circuit.
Bridge
Rectifier: A full-wave rectifier where the diodes are
connected in a bridge circuit. This allows the current to the load
during both the positive and negative alternating of the supply
voltage.
BTU:
"British Thermal Unit", the amount of thermal energy
required to raise one pound of water 1degree F. One BTU is equal to
.293 watt hours. One kWh is equal to 3412 BTUs
C
Canadian
Standards Administration:
CSA
~LINK~
Capacitor:
A device used to store electrical energy in an
electrostatic field until discharge.
Cathode:
A negative (-) electrode. The point of entry of
electrons into a device from an external circuit. The negative
electrode of a semiconductor diode.
Celsius:
A temperature scale. Also known as centigrade. Sea
level water will freeze at 0°C and will boil at 100°C.
Charge:
The measured amount of electrical energy that
represents the electrostatic forces between atomic particles. The
nucleus of an atom has a positive charge (+) and the electrons have a
negative charge(-).
Chatter:
The rapid on/off cycling of a relay caused by improper
signal or adjustment, faulty contacts, or other malfunction.
Circuit:
A full path of electrical current from a voltage source
that passes completely from one terminal of the voltage source to
another.
CMV:
"Common Mode Voltage." The voltage which is
tolerable between signal and ground.
Conductance:
The measure of the ability of a material or substance
to carry electrical current.
Conduction:
The moving of electricity or heat through a conductor.
Conductor:
A material used to conduct electricity or heat.
Conduit:
A tube, pipe or trough that carries and protects
electric wiring.
Coulomb:
A unit of electric charge. The amount of charge
conveyed in one second by one ampere.
Current:
The rate at which electricity flows, measured in
amperes, 1 ampere = 1 coulomb per second.
Current
Proportioning: In a temperature controller it is the
output form that provides a current proportional to the amount of
control that is required. Commonly it is the 4 to 20 milliamp current
proportioning band that is used in the electronics industry.
Cycle:
or Hertz; The measurement of the time period of one
alternating electric current. In the United States this is commonly
60 cycles per second, or 60 Hertz.
Cycle
Time: The time it takes for a controller to complete
one on/off cycle.
D
Delta:
In a three phase connection all three phases are
connected in series thus forming a closed circuit.
Dilectric:
Non-conducting material used to isolate and/or insulate
energized electrical components.
Diode:
A device having two terminals and has a low resistance
to electrical current in one direction and a high resistance in the
other direction.
Direct
Current: (DC); Electrical current that flows
consistently in one direction only.
E
Efficiency:
Output power divided by input power, (work performed in ratio to
energy used to produce it).
Electric
circuit: An arrangement of any of various conductors
through which electric current can flow from a supply current.
Electricity:
A form of energy produced by the flow of particles of
matter and consists of commonly attractive positively (protons [+])
and negatively (electrons [-]) charged atomic particles. A stream of
electrons, or an electric current.
Electrochemistry:
Chemical changes and energy produced by electric currents.
Electrode:
An anode (+) or cathode (-) conductor on a device through which an
electric current passes.
Electroduct:
An interconnected arrangement of parts for carrying
high-voltage electricity.
Electrodynamic:
The interaction of magnetism and electrical current.
Electrokinetics:
The behavior of charged particles and the steady motion of charge in
magnetic and electric fields.
Electrolysis:
Electric current passing through an electrolyte which
produces chemical changes in it.
Electrolyte:
An electrically conductive fused salt or a solution where the charge
is carried by ionic movement.
Electromagnet:
A coil of wire wound about a magnetic material, such as
iron, that produces a magnetic field when current flows through the
wire.
Electromagnetic
field: Electric and magnetic force field that surrounds
a moving electric charge.
Electron:
A fundamental negatively (-) charged atomic particle that rotates
around a positively (+) charged nucleus of the atom.
Environmental
Protection Agency:
EPA;
~LINK~
F
Farad:
The unit for capacitance. A capacitor that stored one coulomb of
charge with one volt across it will have a value of one farad.
Field
cell: Commonly used in generators and motors, it is an
electromagnet formed from a coil of insulated wire that is wound
around a soft iron core.
Field-Effect
Transistor (FET): A three terminal semiconductor
device. In a "FET" the current is from source to drain
because a conducting channel is formed by a voltage field between the
gate and the source.
Filament:
The element inside a vacuum tube, incandescent lamp or
other similar device.
Filter:
A circuit element or components that allows signals of
certain frequencies to pass and blocks signals of other frequencies.
Fluorescent:
The quality of having the ability to emit light when
struck by electrons or another form of radiation.
Flux:
The rate of transfer of energy.
Forward
resistance: When there is current through a
semiconductor p-n junction it is the resistance of a forward-biased
junction.
Forward
Voltage: The voltage that is applied across a
semiconductor junction to permit forward current through that
junction and the device. Forward voltage is also known as "bias."
Frequency:
Also known as Hertz, it is the number of complete
cycles of periodic waveform that occur during a time period of one
second.
G
Gain:
The increase of the power level, current or voltage of
a signal. In an amplifier it is the ratio of the output to the input
signal levels.
Ground:
A reference point at zero potential with respect to the
earth. In an electronic circuit it is the common return path for
electric current. A conducting connection between the earth and an
electrical circuit or electrical equipment. Also, the negative side
of DC power supply.
Grounded:
A connected path to earth or to a conductive body that has a
reference potential to earth.
Grounded
Conductor: A circuit conductor that is grounded to
become part of the electric circuit by design and intent.
Grounding
Conductor: The conductor that is used by intent to
connect the grounded circuit of an electrical wiring system or
equipment to a grounding electrode with reference to earth.
H
Hard
Wired: That part of a circuit which is physically
interconnected.
Hazardous
Location: An area in which combustible or flammable
mixtures are or could be present.
I
I:
Intensity. The commonly used symbol used to represent Amperes when
used in formulas. I = Intensity = Current = Amps = Amperes.
Impedance:
The opposition to electrical flow.
Infrared:
The form of radiation used to make non-contact temperature
measurements. In the electromagnetic spectrum it is the area beyond
red light from 760 nanometers to 1000 microns.
Ingress
Protection Ratings: European environmental ratings.
Similar to NEMA ratings in the USA. IP;*site
has NEMA comparisons ~LINK~
Institute
of Electrical and Electronics Engineers: IEEE;
~LINK~
Interface:The
method by which two devices or systems are connected and interact
with each other.
International
Brotherhood of Electrical Workers:IBEW;
~LINK~
International
Electrotechnical Commission:IEC;
~LINK~
International
Organization for Standardization:ISO;
~LINK~
Intrinsically
safe: A device, instrument or component that will not
produce any spark or thermal effects under any conditions that are
normal or abnormal that will ignite a specified gas mixture.
Electrical and thermal energy limits are at levels incapable of
causing ignition. It is common practice to use external barriers with
intrinsically safe installations.
Instrument
Society of America:ISA;
~LINK~
Isothermal:
A process that is kept at a constant temperature.
J
Joule:
The basic of thermal energy. The work done by the force
of one newton acting through a distance of one meter.
K
Kilovolt:
kV; One thousand volts.
Kilovolt
amperes: Kva; One thousand volt amps.
Kilowatt:
Kw; One thousand watts.
Kilowatt
Hour: Kwh; One thousand watt-hours.
L
Lag:
The time delay between the output signal and the response time of the
receiver of the signal.
Latching
logic: The modification of a signal that causes the
output to remain energized until it is released by intent.
Latent
heat: The amount of heat needed to convert one pound of
water to one pound of steam. Latent heat is expressed in BTU per
pound.
Leakage
current: A small current leaking from an output device
in the off state caused by semiconductor characteristics.
Light
Emitting Diode: LED; A solid state light source
component that emits light or invisible infrared radiation.
Load:
The electrical demand of a process. Load can be
expressed or calculated as amps (current), ohms (resistance) or watts
(power).
M
M:
Symbol for Mega, one million.
Magnetic
Blow-out Switch: A switching device used in switching
high DC loads. It contains a small permanent magnet which deflects
arc in order to quench it.
Magnetic
Field: A region of space that surrounds a moving
electrical charge or a magnetic pole, in which the electrical charge
or magnetic pole experiences a force that is above the electrostatic
ones associated with particles at rest.
Magnetic
Flux: Expressed in webers, it is the product of the
average normal component of the magnetic intensity over a surface and
the area of that surface.
Make:
To close an electrical circuit. To establish an
electrical circuit through the closing of a contact, switch or other
related device.
Manual
Reset Switch: A switch in a controller that manually
resets after exceeding the controllers limit.
Maximum
Load Current: see; "Maximum Power Rating".
Maximum
Operating Temperature: The maximum temperature at which
a device can be safely operated.
Maximum
Power Rating: The maximum watts that a device can
safely handle.
Mean
Temperature: The average temperature of a process.
Microamp:
One millionth of an amp.
Micron:
One millionth of a meter.
Microvolt:
One millionth of a volt.
Mil:
One thousandth of an inch.
Milliamp:
mA; One thousandth of an amp.
Millimeter:
mm; One thousandth of a meter.
Millivolt:
mV; One thousandth of a volt. The difference in potential needed to
cause a current of one milliampere flow through a resistance of one
ohm.
Modulated
Light Source Control: MLS; A photoelectric control that
operates on pulsed infrared radiation at a specific frequency, and
responds only to that frequency of pulse. MLS is used frequently in
areas where ambient light may cause problems with other types of
sensors.
Momentary
switch: A switch with contacts that are made with
actuating force and released when that force is removed.
Mueller
Bridge: A highly accurate bridge configuration that is
used to measure three-wire RTD thermometers.
N
National
Electrical Code: NEC: A set of regulations pertaining
to electrical installation and design in the interest of the
protection of life and property. The NEC is adopted by NFPA and
approved by ANSI. It is the preferred standard of guidelines used by
most electrical regulatory boards in the USA.
National
Electrical Manufacturers Association:NEMA;
~LINK~
National
Fire Protection Association:NFPA;
~LINK~
N.C.:
Normally Closed.
N.O.:
Normally Open.
O
Occupational
Safety & Health Administration:OSHA;
~LINK~
Ohm:
The unit by which electrical resistance is measured.
One ohm is equal to the current of one ampere which will flow when a
voltage of one volt is applied
Ohmeter:
A meter used to measure electrical resistance in units
of ohms.
On/Off
Controller: A controller whose action is either fully
on or off.
Open
Circuit: An electrical circuit that is not "made".
Contacts, switches or similar devices are open and preventing the
floe of current.
Operating
Temperature: The range of temperature over which a
device may be safely used. The temperature range which the device has
been designed to operate.
OR
Logic: The output that is produced when one or more
inputs are present.
Output:
The energy delivered by a circuit or device. The
electrical signal produced by the input to the transducer.
P
Phase:
The time based relationship between a reference and a periodic
function.
Phase
Proportioning: A form of control where the power
supplied to a process is controlled by limiting the phase angle of
the line voltage.
PID:
A three mode control consisting of time Proportioning,
Integral and Derivative rate action.
Plasma:
An ionized gas containing about equal numbers of positive and
negative charges, which is a good conductor of electricity, and is
affected by a magnetic field.
Polarity:
Magnetically, opposite poles, north and south. In electricity,
oppositely charged poles, positive and negative.
Potentiometer:
A variable resistor.
Power
Dissipation: The amount of power that is consumed and
converted to heat.
Power
Supply: The part of a circuit that supplies power to
the entire circuit or part of the circuit. Usually a separate unit
that supplies power to a specific part of the circuit in a system.
Process
Meter: A panel meter with zero and span adjustments,
commonly scaled for signals such as 1-5 volts, 4-20mA, etc.
Proximity
Sensor: A sensor or switch with the ability to detect
it’s relationship to a metal target without making physical
contact.
Proximity
Switch: see; "Proximity Sensor".
PSIA:
Pounds per square inch absolute. Pressure commonly in reference to
vacuum.
PSID:
Pounds per square inch differential. The difference in
pressure between two points.
PSIG:
Pounds per square inch gage. Pressure in relationship
to the ambient air pressure>
Pulse:
A rise and fall of voltage, current, or other faction
that would be constant under normal conditions. A pulse that is
intentionally induced will have a finite duration time.
Q
Quality
Control: Inspection, analysis and action required to
ensure quality of output.
Quantum:
One of the very small discrete packets into which many
forms of energy are subdivided.
Quantum
Electronics: Applying molecular physics to electronics.
Quap:
A hypothetical nuclear of a quark plus an antiproton.
Quark:
A hypothetical basic subatomic nuclear particle believed to be the
basic component of protons, neutrons, etc.
Quartz:
A form of silicone dioxide. Commonly used in the making of radio
transmitters and heat resistant products.
Quartziodine
Lamp: A high-intensity incandescent lamp with a quartz
bulb containing an inert gas of iodine or bromine vapor.
Quasiparticle:
A unit of energy in solid-state physics with mass and momentum but
that does not exist as a free particle.
Q-value:
The amount of energy released in a nuclear reaction. It
is expressed in atomic mass units, or in million electron volts
(MEV).
R
Rectifier:
A device that converts AC voltage to pulsating DC voltage.
Relay:
A Solid State relay is a switching device that completes or
interrupts a circuit electrically and has no moving parts. A
Mechanical relay is an electromechanical device that closes contacts
to complete a circuit or opens contacts to interrupt a circuit.
Resistance:
The resistance to electrical current. Resistance is
measured in ohms.
Response
Time: The amount of time it takes for a device to react
to an input signal.
RFI:
Radio Frequency Interference.
Rheostat:
A variable resistor.
Ripple:
A fluctuation in the intensity of a steady current.
Root
Mean Square: RMS; AC voltage that equals DC voltage
that will do the same amount of work. For an AC sine wave it is 0.707
x peak voltage.
RTD:
Resistance Temperature Detector.
S
SCR:
Silicone Controlled Rectifier.
Series
Circuit: A circuit which may have one or many resistors
and/or other various devices connected in a series so that the
current has only one path to follow.
Supply
Current: Current Consumption. The amount of amps or
milliamps needed to maintain operation of a control or device.
Supply
Voltage: The range of voltage needed to maintain
operation of a control or device.
System
International: SI; The standard metric system of units.
T
Thermistor:
An electrical resistor composed of semiconductor material, whose
resistance is a known rapidly varying function of temperature.
Thermocouple:
Two dissimilar metals connected at a point, that
produce an electrical current whose magnitude is dependent upon the
temperature at the junction point.
Thermoelectricity:
Electrical energy produced by the action of heat.
Threshold
Response: Response to the change in the level of the
input signal.
Thyristor:
A solid-state switching device for semiconductors to
convert AC current in one of two directions controlled by an
electrode.
Time
Delay Before Availability: The delayed period of time
when outputs are turned off when power is initially applied.
Transducer:
A device that transfers power or energy from one system
to another, such as taking a physical quality and changing it to an
electrical signal.
Transient:
A sudden and unwanted increase or decrease of supply voltage or
current.
Transient
Protection: Protective circuitry to guard against
spikes that might be induced on the supply line.
Transistor:
A device incorporating semiconductor material and
suitable contacts capable of performing electrical functions (such as
voltage, current or power amplification) with low power requirements.
Triac:
A solid-state switching device used in switching AC
wave forms.
U
UHF:
Ultra High Frequency
Underwriters
Laboratories:UL;
~LINK~
V
Vacuum:
Pressure that is less than atmospheric pressure.
Vector:
The magnitude and time phase of a quantity, represented
by a plotted line.
Velocity:
The speed or time rate of change of displacement.
VF:
Variable Frequency.
VHF:
Very High Frequency.
Volt:
Voltage; The unit of electromotive force (EMF) that
causes current to flow. One volt causes a current of one amp through
a resistance of one ohm.
Voltage
Drop: The difference in potential measured between two
points caused by resistance or impedance.
Voltmeter:
A meter used to measure units of volts.
VOM:
Volt-ohm Meter.
W
Watt:
The unit of power. One watt equals one joule per
second, 1/746th horsepower.
Watt-hour:
The power of one watt operating for one hour, and equal to 3,600
joules.
Weber:
The standard unit of magnetic flux.
Working
Standard: The standard that is used to make comparison
measurements or calibrations.
X
XFMR:
Symbol used to denote transformer.
XMTR:
Symbol used to denote transmitter.
X
ray: An electromagnetic radiation produced when the
inner satellite electrons of heavy atoms have been excited by
collision with a stream of fast electrons return to their ground
state, giving up the energy previously imparted to them.
Y
Y:
Symbol used for wye configuration for three phase
electrical connections.
Z
Zener
Diode: A silicone semiconductor that maintains a fixed
voltage in a circuit.
Zener
Effect: The pronounced curvature in reverse voltage
current that is characteristic of a diode.
Zero
Adjustment: The adjustment of a display that results
are zero on the display corresponding to a non-zero signal.
