Insulators


An insulator is a material that does not conduct electrical current. Insulating materials include paper, plastic, rubber, glass and air. Vacuum is also an insulator, but is not actually a material. Most electrical conductors are covered by insulation. Magnet wire is coated with an extremely thin layer of insulation so that more turns or larger wire may be used in the winding of transformers etc. Insulators are generally rated at hundreds of volts, but some that are used in power distribution are rated as high as hundreds of thousands of volts. Insulators support and/or keep electrical conductors from making unintended contact with each other.

Insulator made by hard paste of Porcelain is also known as true porcelain insulator. Out of all the wide varieties of ceramics & true porcelain is the hardest, the most durable - which is one of the reasons porcelain insulator are largely replaced glass insulators.

Porcelain in most typically used material for overhead insulator in present days. The porcelain is aluminum salt. The atomic number 13 salt is mixed with plastic porcelain clay, spar and quartz to get final laborious and glazed porcelain material. The surface of the insulator ought to be glazed enough in order that water shouldn't be derived on that. Porcelain conjointly ought to be free from porosity since porosity is the main reason for deterioration of its dielectric property. It should even be free from any impurity and bubble within the material which can have an effect on the insulator properties. Related Projects: - Electrical, Electronic Industries and Power Project.

In atoms that have a large range of electrons within the outer orbit, the combined force of attraction for the nucleus is way stronger, therefore it's more difficult to force a lepton out of orbit, and substances made from these sorts of atoms are referred to as insulators. In alternative words the substances, that strongly oppose flow of electrons through them, are termed as insulators.

Low-tension insulators are used for A.C. & D.C. power supplies of not more than 600 volts. Low tensions insulators are manufactured in both glazed and unglazed insulators are quite satisfactory. Insulators required for use in humid atmosphere are invariably glazed. Glazed insulators are used in lighting arrestors in radio receivers, telephone and utility outfits and neon signs. Some L.T. insulators like nail knobs, tubes & cleats are glazed on one side.

Properties of Porcelain Insulator:- Dielectric Strength : 60 kV / cm
Compressive Strength : 70,000 Kg / cm2
Tensile Strength : 500 Kg / cm2


Voltage above 1000 Volts is generally considered as high tension for long distance Electric power transmission; high voltage is essential because it reduces the cross/section and, therefore, the weight of the conductor required. Porcelain insulators are suitable for high tension transmission & distribution are required to be effective at high voltages and under extreme climate conditions of rain, snow, high wind of soaring heat.

Types of Insulators:
1) Pin insulators.
2) Solid post insulators.
3) Suspension insulators.
4) Hollow insulators.
5) Long rod single piece porcelain insulators.

Manufacturing Process:

The first process is weighing of all raw materials for a batch system wherever the higher than materials from the storage bins when crushing & grinding and pulverizing to the required fineness are weighed because the required composition and thenceforth directly plunged into a ball mill. The slip is then passed through electro-magnets before discharging in to the provocative tanks for more feeding to the filter press. Within the filter presses, the clay cakes are shaped and more established the needing pug mill to from blanks. These blanks are then formed as insulators. Later the insulators are dried within the drying chambers and so glazed by the manual method. When Glazing, the insulators are loaded on the kiln-cars when careful scrutiny.
Finally the material is then sorted out by the quality control experts and sent for electrical testing. Insulators, which pass through the electrical tests, are sent for assembly with metal parts. After curing insulators are again tested for electro-Mechanical properties and are packed and sent to the warehouse.
 Milling
 Filtering
 Extruding
 Shaping
 Glazing
 Firing

Advantages of Porcelain Insulators:

 Environmental friendly. At its disposal, the porcelain insulator is not dangerous waste
 In comparison to the polymer, electrical strength of porcelain is higher: 25+ kV/mm v. 20 kV/mm at the polymer
 The porcelain insulator has demonstrably higher resistance to degradation of the surface, does not degrade or carbonate during charges; the conductive path is created very slowly in comparison of the surface of a composite-material insulator
 The ceramic material is resistant to rodents, termites, birds and other animals capable of compromising the integrity of polymers
 The porcelain insulator has a wide scope of application: Contactors, disconnections, equipment transformers, condensers, and grommets also with extreme surface, atypical insulators (filters)
 The porcelain insulator is suitable for extreme hot/cold changes in the environment. It is suitable for environments with dust, salt and high moisture, or for combination of all of the above
 The ceramic material offers very high mechanical strength under pressure and hardness
 The design is modified to suit the environment

The ceramic insulators usually have a higher dielectric constant, that doesn't vary abundant with variable temperature, unlike glass, that conducts a lot of electricity at elevated temperatures, i.e., the insulator constant of glass varies with temperature.

The demand for ceramic electrical insulators is expected to be driven by the increasing transmission and distribution network, supported by growing energy consumption, penetration of renewables within the world energy mix, among varied alternative factors.