![]() Insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. Examples include rubber-like polymers and most plastics which can be thermoset or thermoplastic in nature. 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. Some materials such as glass, paper and PTFE, which have high resistivity, are very good electrical insulators. This is known as electrical breakdown, and the voltage at which it occurs is called the breakdown voltage of an insulator. In addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. The most common examples are non-metals.Ī perfect insulator does not exist because even insulators contain small numbers of mobile charges ( charge carriers) which can carry current. The property that distinguishes an insulator is its resistivity insulators have higher resistivity than semiconductors or conductors. Other materials- semiconductors and conductors-conduct electric current more easily. The atoms of the insulator have tightly bound electrons which cannot readily move. Ceramic insulator used on an electrified railway Three-core copper wire power cable, each core with an individual colour-coded insulating sheath, all contained within an outer protective sheathĪn electrical insulator is a material in which electric current does not flow freely.
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