Electrical Insulators Information

Ceramic insulatorElectrical insulators and high voltage bushings, or porcelain insulator assemblies, provide electrical isolation of power line conductors in transmission and distribution (T & D), substation, transformer, capacitor and power protection applications.


There are many types of electrical insulators and high voltage bushings. Examples include:

  • die-cut electrical insulators
  • porcelain insulators
  • ceramic insulators
  • laser-cut electrical insulators
  • standard electric insulators
  • transformer bushings

A die-cut electrical insulator consists of a thin film over the surface of equipment. A porcelain insulator is very reliable and capable of withstanding the electrical strain of high voltage. A ceramic insulator is made of ceramic materials and can resist extreme thermal conditions. A laser-cut electrical insulator has special spatial characteristics. A standard electric insulator is non-metallic and blocks the flow of electricity because its valence band is filled; however, the energy gap is relatively wide. A transformer bushing improves the field distribution inside a transformer. Other types of electrical insulators and high voltage bushings are also available.


Selecting electrical insulators and high voltage bushings requires an analysis of specifications, features, and application requirements. There are many different types of insulator materials, including plastics, porcelain, mica, or alumina.

  • An electrical insulator insulates a power line to prevent fire or electrical shock.
  • A die-cut electrical insulator is durable and includes fish paper, which is die cut and then machined.
  • A porcelain insulator has a puncture-proof body and consistent mechanical strength.
  • A ceramic insulator provides protection against chemical and thermal conditions.


Electrical insulators and high voltage bushings are used in many applications and meet a variety of regulatory requirements and quality standards. Some products are used in automobile and aircraft instrumentation, computers, or medical analysis equipment. Others are designed for telecommunications devices or enclosures for electronic systems.


Electric insulators and high voltage bushings should adhere to standards from the American National Standards Institute (ANSI) or the Institute for Electrical and Electronics Engineers (IEEE).

Image credit:

Thermos / CC BY-SA 3.0