What is Electrical Insulating Material?
Liang Zhang
General Manager at ENC GROUP LTD. Specializing in electrical insulation materials, transformer materials and spare parts.
The material which does not allow the electricity to pass through them is known as an electrical insulating material. The charge of the insulating material does not move freely, or in other words, it provides the high resistive path to the electric current through which it is nearly impossible for the electric current to conduct through it. It is used in the overhead transmission line between the tower and conductor for preventing the flow of electric current from the conductor to earth.
Basically, an insulating material or insulator contains a very small amount of free electrons (charge carriers) and, hence, could not carry electrical current. But, a perfect insulator does not exist, because even insulators contain a small number of charge carriers which may carry leakage current (negligibly small). In addition, all insulators become conductive when sufficiently large voltage is applied. This phenomenon is called as insulation breakdown and the corresponding voltage is called as breakdown voltage.
An insulating material must have high resistivity and high dielectric strength. Additional desirable properties of insulating material depend on the type of applications. Insulating material used for manufacturing insulated cables/wires must be flexible such as rubber or PVC. On the other hand, insulator used to support overhead power lines must be mechanically strong, such as porcelain or glass insulators.
Features:
1.The material must have high mechanical strength so that it carries the tension and weight of the conductors.
2.They must have high dielectric strength.
3.The material is highly resistive for preventing the flow of leakage current from the conductor to earth.
4.The material is non-porous and free from impurities.
5.The electrical and chemical property of the material should not be affected by the temperature.
Function:
Purpose of an insulator is to prevent the unwanted flow of current from the energized conductor or conducting parts. Electrical insulation plays a vital role in every electrical system. An electrical insulator provides very high resistance so that practically no current can flow through it.