Electrical Cable can come with insulation or not. There are some type of over head transmission and distribution cable don’t have insulation on it because it stay up from ground level. But if a cable is passing through ground level and human and animal is crossing nearby then there is a big possibility that anyone can get Electrical Shock if the cable is not having insulation.
Like cable insulation a cable insulator is also important equipments in power transmission and distributions system. It keep safe our transmission and distributions line when line is active. Cable insulator present between tower to tower. In this post we will learn Different Types of Cable Insulators.
What is Cable Insulators:
Insulator is one kind of material that prevents the flow of electric current and can be used to support of electrical conductor. The main function of an insulator is to separate the line conductors from the pole and the tower. Normally the conductor of overhead transmission and distribution line are secured by means of insulator.
It used to prevent the leakage current to the earth through the pole. Jumper safe the line by overloaded. The insulator plays an important roll to a successful transmission & distribution for electrical line. Now the materials most commonly used for an insulator for overhead lines are,
Porcelain is an extensively used material & it produced by firing at very control temperature by a mixture of kaolin, feldspar and quartz. It is mechanically stronger than the glass. Porcelain surface is not affected by any a kind of dirt deposits and it is less susceptible to changes of temperature.
Porcelain insulator has much dielectric strength and its about 60KV/cm of it thickness. The compressive strength of a good porcelain is about 70000 Kg/ cm2 and tensile strength is about 500kg/cm2.
Glass is little bit cheaper than porcelain in the simple shapes and if property toughens and the follow annealed gives resistivity and very high dielectric strength. Glass is quite a homogeneous materials and very high compressive stress. It s very lower co-efficient of thermal expansion.
Owing to its transparent nature it can be readily by a visual inspection. The main disadvantage of glass is that, moisture is easily condensed on its surface.
Steatite is naturally occurring magnesium silicate and it usually found combined with oxides in varying proportion. Steatite has higher tensile and bending stress than porcelain and glass. It can easily be used between tension towers or when the transmission line takes very a sharp turns.
Synthetic is a non ceramic insulators and its consists of a fiber glass rod covered by weather shed or skirts of polymer.
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