Electrical Engineering Topics

AC Brownout
The condition that exists when the ac line voltage drops below some specified value.
AC Induction Motors
These are generally used for constant speed applications where a fixed frequency power source such as 60 Hz or 400 Hz is available.
AC Line
The set of conductors that route ac voltage from one point to another.
AC Line Filter
A circuit filter placed in the ac line to condition or smooth out variations that are higher in frequency than the line frequency.
AC Voltage
The AC voltage is normally given as the RMS value.
AC
An electric current whose direction changes direction with a frequency independent of circuit components.
Air Blast Circuit Breaker
A circuit breaker using compressed air to force the extinction of the arc through an arc-chute system.
Air Circuit Breaker
Automatically interrupts the current flowing through it when the current exceeds the trip rating of the breaker.
Amperage
The amount of current flow within a circuit, expressed in amps.
Anti-Single Phase Tripping Device
A device that operates to open all phases of a circuit by means of a polyphase switching device, in response to the interruption of the current in one phase.
Arc Flash
An electrical explosion that results from a low-impedance connection to ground or another voltage phase in an electrical system.
Arc-Resistance Switchgear
Switchgear designed to withstand the effects of an internal arcing fault, without causing harm to personnel.
Basic Impulse Insulation Level
A reference impulse insulation strength expressed in terms of the crest value of the withstand voltage of a standard full impulse voltage wave.
Battery Bank
A group of batteries used to store energy and so even out supply and demand issues with sources such as wind energy.
Biot
Another name for the Abampere.
BLDC Motor
Abbreviation of Brushless DC Motor.
Bolted Fault
A short circuit condition that assumes zero impedance exists at the point of the fault.
Brush DC Motors
The Brush DC motors use commutators and carbon brushes to apply current through the windings as the motor rotates.
Brushless DC Motors
The BLDC motor uses electronic commutation to control the current through the windings.
Burden
The load impedance imposed by a relay on its source.
Bus
Transmission medium for electrical or optical signals that perform a particular function, such as computer control.
Busbar
Copper bar or section used for carrying heavy currents, generally rigid when compared to cables.
Capacitor Start Motor
A type of single-phase, ac induction motor in which a starting winding and a capacitor are placed in series to start the motor.
Cartridge Fuse
A low voltage fuse consisting of a current-responsive element inside of a fuse tube with connection terminals on both ends.
Circuit Breaker
A protective device used to open a circuit when current exceeds a maximum value.
Closing Time
The amount of time from the initiation of the closing operation and the instant when metallic continuity is established in all phases.
Compound Wound Motors and Generators
Machines that have a series field in addition to a shunt field.
Contactor
A contactor is a device for opening and closing an electric power circuit.
Control Relay
An auxiliary relay whose function is to initiate or permit the next desired operation in a control sequence.
Control Voltage
The voltage of the power supply used to energize a device in the switchgear.
Counter EMF
Another name for Back Electromotive Force.
Creepage Distance
The shortest distance along the surface of an insulator from one conducting part to another, which may be energized or at ground potential.
Definite Time Relay
A relay in which the operating time is substantially constant regardless of the input quantity.
Discharge Curve
Graphical representation of the change in output voltage over time under various loads and/or temperature.
Discharge Factor
A number equivalent to the time in hours during which a battery is discharged at constant current, usually expressed as a percentage of the total battery capacity, i.e., C/3 indicates a discharge factor of 3 hours.
Distribution Circuit Breaker
A device used for overload and short current protection of loads connected to a main distribution device.
Dual Element Fuse
A fuse having responsive elements of two different fusing characteristics in a single series of fuse.
Electric Motor Bearings
The bearings that support the armature and allow it to rotate relative to the stator.
Electric Motor Efficiency
The efficiency of a motor is the ratio of electrical power input to mechanical power output.
Electric Motor Failure
Most motor failures stem from damaged bearings or stator windings.
Electric Motor Load
Any device driven by a motor.
Electric Motor Noise
There are numerous applications of electric motors and the type of noise produced by each may be very specific to the installation and type of motor.
Electric Motor Reaction
The force created by generator armature current that tends to oppose the normal rotation of the armature.
Electric Motor Starter
Large resistive devices placed in series with dc motor armatures to prevent the armature from drawing excessive current until armature speed develops counter emf.
Electric Motor Windings
Wires that are laid in coils, usually wrapped around a laminated soft iron magnetic core so as to form magnetic poles when energized with current.
Electric Motors
There are a number of different types of electric motor: AC Induction Motors, Brush Direct Current Motors, Brushless Direct Current Motors and Stepper Motors.
Electrical Engineer
An engineer concerned with electrical devices and systems and with the use of electrical energy.
Electrical Engineering Books
Lists all Electrical Engineering Books in the Encyclopaedia
Electrical Engineering Calculations
Lists all Electrical Engineering Calculations in the Encyclopaedia
Electrical Engineering Conversions
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Electrical Engineering Weblinks
Lists all Electrical Engineering Weblinks in the Encyclopaedia
Electrical Resistance
The ability of a material to oppose the flow of an electric current, converting electrical energy into heat.
Energy Efficiency
Ratio of energy output of a conversion process or of a system to its energy input.
Expulsion Fuse
A vented fuse or fuse unit in which the expulsion effect of gases produced by the arc and the lining of the fuse holder, either alone or aided by a spring, extinguishes the arc.
Filter Capacitor
A capacitor employed in power supplies for ripple reduction.
Filter Choke
An inductor used in power supplies for ripple reduction.
Fusible Link
An electrical or mechanical link designed to break under high current or other mechanical input and so break a circuit.
Generating Capacity
The maximum amount of electric power produced by a generator.
Generator
A machine that converts mechanical energy to electrical energy by applying the principle of magnetic induction.
Generator Set
A generating system comprising a combustion engine driving an electrical generator.
Grid Based Energy Storage
Energy storage system connected to the electricity grid that is designed to smooth supply and demand requirements.
Impedance Matching
Maximum power is transferred from one circuit to another when the output impedance of the one is matched to the input impedance of the other.
Induction Motor
The rotor is energized by transformer action from the stator.
Insulation
A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor.
Insulator
A material that does not allow the passage of electric charge or is a poor conductor of thermal energy.
Inverse Time Relay
A relay in which the input quantity and operating time are inversely related throughout at least a substantial portion of the performance range.
Islanding
Relates to distributed generation where local generators continue to power a location when power from the electricity grid is no longer present.
Isolation Voltage
The voltage that an isolated circuit can normally withstand, usually specified from input to input.
Light Bulb
A device that takes an electric supply and generates light.
Linear Motor
A motor consisting of two parts, typically a moving coil and stationary magnet track.
MA
Abbreviation of Mega-Ampere = 1 million Ampere.
Mains Electrical Power Specification
In the UK 230V AC 50Hz.
Mains Frequency
Electricity ac supply frequency; 50 Hz in UK, 60 Hz in US.
Mains Noise
Unwanted noise in electrical signals related to mains signals.
Minimum Oil Circuit Breaker
A circuit breaker using a relatively small quantity of mineral oil for its arc-interruption method.
Motor
A mechanism doing work by means of a ready source of energy, such as electric current, compressed air, or oil under pressure.
Nominal System Voltage
A nominal value assigned to designate a system of a given voltage class.
Ohm Metre
A unit of resistivity, measuring the extent to which a substance offers resistance to passage of an electric current.
Over Current Device
A device such as a fuse or a circuit breaker designed to protect a circuit against excessive current by opening the circuit.
Paschen Law
Theoretical relationship for the direct-current breakdown voltage of parallel-plane electrodes immersed in a gas as a function of the gas pressure and electrode separation.
Peak Load
The maximum demand for electricity from an electrical system in a given period of time.
Photovoltaic Array
An interconnected system of PV modules that function as a single electricity-producing unit.
Photovoltaic System
The complete set of components for converting sunlight into electricity by the photovoltaic process, including the array, inverter and the balance of system components.
Planar Power Transformer
A stacked layer design transformer.
Polarity
The positive or negative direction of an electrical, acoustical or magnetic force.
Power Supply
A unit that supplies electrical power to another unit.
Propagation Test
Test to look at how an event such as combustion propagates from one component to the next.
Protective Devices
Devices, such as fuses, diodes and current limiters which interrupt the current flow, block the current flow in one direction or limit the current flow in an electrical circuit.
Pulse Width Modulated Wave Inverter
A type of power inverter that produces a nearly sinusoidal voltage, at minimum current harmonics.
Quick to Break
A device that has a high contact opening speed which is independent of the operator.
Quick to Make
A device that has a high contact closing speed which is independent of the operator.
Relay
Electromechanical device containing a coil and set of contacts. The contacts close when the coil is activated.
Resistive Load
An electrical load where the time phase sequence of the current and the voltage is such that the current and the voltage are in phase with each other.
Rotary Inverter
A device having a combination motor generator with a governor which inverts DC to AC.
Seal-in Relay
An auxiliary relay that remains picked up through one of its own contacts, which bypasses the initiating circuit until de-energized by some other device.
Self Excited Generators
DC generators in which the generator output is fed to the field to produce field excitation.
Series Wound Motor and Generator
Electric motor in which the armature and field windings are connected in series with each other.
SF6 Circuit Breaker
A circuit breaker that uses SF6 gas for its interrupting method.
Short-Circuit
An un-intended path that conducts electricity.
Shunt Wound Motor and Generator
Machines in which the armature and field windings are connected in parallel with each other.
Sine Wave Inverter
An inverter that produces utility-quality, sine wave power forms.
Single Element Fuse
A fuse having a current responsive element comprising one or more parts with a single fusing characteristic.
Solar Power System
Concept for providing large amounts of electricity for use on the Earth from one or more satellites in geosynchronous Earth orbit.
Spark
Electrically the bridging or jumping of a gap between two electrodes by a current of electricity. A physical spark could be from a small hot particle or ember.
Switchgear
The combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment.
Synchronous Inverter
A unit which converts dc current to ac while at the same time regulating frequency to that of the power line.
Synchronous Motor
An AC motor whose rotor is activated by DC.
Systems Engineering
Lists all Systems Engineering topics in the Encyclopaedia
Terminal Voltage
The voltage at the battery or electrical power source terminals.
Thermal Relay
A switching relay in which a small heater warms a bimetal element which bends to provide the switching force.
Third Brush
A generator in which a third, movable brush is used to control current output.
Tie Feeder
Connects together two or more independent sources of power and has no tapped load between the terminals.
Transfer Switch
A switch or switches arranged to permit transferring a conductor connection from one circuit to another without interrupting the current.
Transformer Oil
A highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties.
Transient Inrush Current
The current that results when a switching device is closed to energize a capacitive or inductive circuit.
Transient Overvoltage
The voltage which occurs during the transient conditions resulting from the operation of a switching device.
Trip Free Circuit Breaker
A circuit breaker that will open a circuit even if the operating mechanism is held in the ON position.
Trip-Free Relay
An auxiliary relay whose function is to open the closing circuit of an electrically operated switching device so that the opening operation can prevail over the closing operation.
Uninterruptible Power Supply
A type of power supply designed to support the load for specified periods when the line varies outside specified limits.
Voltage Regulator
A device or design implementation which regulates the electromotive force.
Voltampere (VA)
The product of rms voltage and rms current in an electronic circuit. It is the unit of apparent power in the International System of Units (SI).
Wind Turbine
A device that converts kinetic energy from the wind, also called wind energy, into mechanical energy; a process known as wind power.
Wireless Charging
A charging system that has a physical gap between the input and the system that is to be charged.
Withstand Voltage
The specified voltage that can be applied to insulation under specified conditions without causing flashover or puncture to occur.

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