Types of Insulators In Overhead Transmission Lines
Transmission line insulators separate, contain and suspend transmission line conductors.they protects short circuit path between earth and transmission line.There are several types of insulators In overhead transmission lines.but the most know are pin type, suspension type, strain insulator,shackle insulator and Stay Insulator.Types of electrical insulators in transmission lines:
1. Pin type insulators:
2.Suspension type insulators :
Advantages of Suspension Type insulators :
(i)Suspension type insulators are very economical voltages beyond 33 kV.
(ii) Each unit or disc of suspension type insulator is designed for low voltage,usually 11 kV.As per requirement of operating voltage we can add no.of discs in series.
(iii) If any one disc is damaged, the whole string does not become useless because the damaged disc can be replaced by the sound one.
(iv) The suspension arrangement provides greater flexibility to the line. The connection at the cross arm is such that insulator string is free to swing in any direction and can take up the position where mechanical stresses are minimum.
(v) The suspension type insulators are generally used with steel towers. As the conductors run below the earthed cross-arm of the tower, therefore, this arrangement provides partial protection from lightning.
3.Strain Type insulators:
Strain type insulators are simply horizontally suspended suspension insulators.When there is a dead end or there is a sharp corner in transmission line, the line has to sustain a great tensile load of conductor or strain.The discs of strain insulators are used in the vertical plane. When the tension in lines is exceedingly high, at long river spans, two or more strings are used in parallel.voltage rating almost equal to suspension type.
4.Shackle Type Insulators:
Shackle type insulators, similar to strain type insulators, are used on sharp curves, end poles and in section poles.These insulators are single, round porcelain parts that are mounted horizontally or vertically.The shackle insulator or spool insulator is usually used in low voltage distribution system.They can be directly fixed to the pole with a bolt or to the cross arm.
5.Stay insulators :
The insulator used in the stay wire is called as the stay insulator and is usually of porcelain and is so designed that in case of breakage of the insulator the guy-wire will not fall to the ground.
This Is Complete Information On Types of Electrical Insulators ; Insulators In Overhead Transmission Lines.
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