An insulator pin is used to hold the insulator that is mounted on top of it in a vertical position. The use of steel is required wherever the pins must be extra long and sturdy due to high voltage and when the conductor is under severe tension.
Insulator pins are bolted onto a cross-arm and the insulator is then screwed onto the top of the pin. The wire is then typically attached to the insulator by being wrapped around it. This isolates the wire from its physical support and as the insulator is made out of a non-conductive material, prevents any significant damage in the event of an electrical failure.
There are three types of overhead insulators: Pin, strain and suspension insulators. Unlike the others, pin insulators are directly connected to the physical support compared to being suspended from the wire. The pin insulator is used in power distribution for the voltage up to 33kV. A pin insulator is not usually used above 33kV, though construction of three or four-piece insulator may be possible but not usually due to the size becoming too bulky and the high weight which would not prove to be economical.
The advantages of an insulator pin are that it has a high mechanical strength; the pin type insulator has good creepage distance. It is normally used vertically but can be used horizontally as well.
Insulator pins come in a variety of sizes from 50mm to 150 mm, one type of pin can be used to hang multiple types of noise insulation, reducing inventory needs.