Insulator (electricity)

insulatorinsulatorsinsulationelectrical insulationinsulatingelectrical insulatorinsulatedelectrical insulatorsnon-conductiveelectrically insulating
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field.wikipedia
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Semiconductor

semiconductorssemiconductingsemiconductor material
This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily.
A semiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic copper, and an insulator, such as glass.

Breakdown voltage

striking voltagereverse voltage reverse breakdown
This is known as the breakdown voltage of an insulator.
The breakdown voltage of an insulator is the minimum voltage that causes a portion of an insulator to become electrically conductive.

Electrical conductor

conductorconductiveconductors
This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily.
Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents.

Electrical insulation paper

paperelectrical insulating paperpressboard
Some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators.
Electrical insulation papers are paper types that are used as electrical insulation in many applications due to pure cellulose having outstanding electrical properties.

Electric current

currentelectrical currentcurrents
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field.
Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.

Electrical breakdown

dielectric breakdownbreakdowndisruptive discharge
When subjected to a high enough voltage, insulators suffer from the phenomenon of electrical breakdown.
Electrical breakdown or dielectric breakdown is when current flows through an electrical insulator when the voltage applied across it exceeds the breakdown voltage.

Mott insulator

Mott insulatorsMottnessMott criticality
Most (though not all, see Mott insulator) insulators have a large band gap.
Mott insulators are a class of materials that should conduct electricity under conventional band theories, but are in fact insulators when measured (particularly at low temperatures).

Band gap

forbidden gapband-gapbandgap
Most (though not all, see Mott insulator) insulators have a large band gap.
In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band in insulators and semiconductors.

Electrical resistance and conductance

resistanceelectrical resistanceconductance
Rapidly the insulator becomes filled with mobile charge carriers, and its resistance drops to a low level.
The resistance of an object depends in large part on the material it is made of—objects made of electrical insulators like rubber tend to have very high resistance and low conductivity, while objects made of electrical conductors like metals tend to have very low resistance and high conductivity.

Printed circuit board

circuit boardPCBprinted circuit boards
In electronic systems, printed circuit boards are made from epoxy plastic and fibreglass.
A printed circuit board (PCB) mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate.

Thermosetting polymer

thermosetthermosetting plasticthermosetting
Examples include rubber-like polymers and most plastics which can be thermoset or thermoplastic in nature.

Metal

metalsmetal ionsmetal ion
This allows electrons to gain energy and thereby move through a conductor such as a metal.
In insulators and semiconductors the Fermi level is inside a band gap; however, in semiconductors the bands are near enough to the Fermi level to be thermally populated with electrons or holes.

Polytetrafluoroethylene

TeflonPTFEePTFE
Some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators.
This application exploits the fact that PTFE has excellent dielectric properties, especially at high radio frequencies, making it suitable for use as an excellent insulator in connector assemblies and cables, and in printed circuit boards used at microwave frequencies.

Utility pole

telephone poletelegraph poletelephone poles
The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers.
The wires themselves are usually uninsulated, and supported by insulators, commonly mounted on a horizontal crossarm.

Electrical wiring

wiringelectrical cablesbuilding wiring
A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to prevent significant current from flowing at normally used voltages, and thus are employed as insulation for electrical wiring and cables.
Electrical devices often contain copper conductors because of their multiple beneficial properties, including their high electrical conductivity, tensile strength, ductility, creep resistance, corrosion resistance, thermal conductivity, coefficient of thermal expansion, solderability, resistance to electrical overloads, compatibility with electrical insulators and ease of installation.

Electric charge

chargeelectrical chargecharged
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field.
John Theophilus Desaguliers, who repeated many of Gray’s experiments, is credited with coining the terms conductors and insulators to refer to the effects of different materials in these experiments.

Glass

glassmakersilicate glassvitreous
Some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators.
Fiberglass is also a good insulator, allowing it to be used to insulate buildings.

Electron

electronse − electron mass
In addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms.
In any dielectric material, the electrons remain bound to their respective atoms and the material behaves as an insulator.

Electronic band structure

band structureband theoryenergy band
Electronic band theory (a branch of physics) said that a charge flows if states are available into which electrons can be excited.

Ampacity

current ratingcurrent-carrying capacitycurrent ratings
It may not have an ampacity (current-carrying capacity) rating, since this is dependent upon the surrounding environment (e.g. ambient temperature).
The ampacity for a conductor is based on physical and electrical properties of the material and construction of the conductor and of its insulation, ambient temperature, and environmental conditions adjacent to the conductor.

Aluminium oxide

aluminaaluminum oxideAl 2 O 3
Porcelain insulators are made from clay, quartz or alumina and feldspar, and are covered with a smooth glaze to shed water.
Al 2 O 3 is an electrical insulator but has a relatively high thermal conductivity (30 Wm −1 K −1) for a ceramic material.

Strain insulator

strainers
Guy wires supporting antenna masts usually have strain insulators inserted in the cable run, to keep the high voltages on the antenna from short circuiting to ground or creating a shock hazard.
A strain insulator is an electrical insulator that is designed to work in mechanical tension (strain), to withstand the pull of a suspended electrical wire or cable.

Short circuit

short-circuitshortelectrical short
However, wires that touch each other produce cross connections, short circuits, and fire hazards.
In electrical devices unintentional short circuits are usually caused when a wire's insulation breaks down, or when another conducting material is introduced, allowing charge to flow along a different path than the one intended.

Bushing (electrical)

bushingbushingstransformer bushings
These hollow insulators with a conductor inside them are called bushings.
In electric power, a bushing is an insulated device that allows an electrical conductor to pass safely through a grounded conducting barrier such as the case of a transformer or circuit breaker.

Transmission tower

electricity pylonpylonspylon
The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers.
Insulators electrically isolate the live side of the transmission cables from the tower structure and earth.