Pin insulator

rdf:langString Pin insulator

rdf:langString A pin insulator is a device that isolates a wire from a physical support such as a pin (a wooden or metal dowel of about 3 cm diameter with screw threads) on a telegraph or utility pole. It is a formed, single layer shape that is made out of a non-conducting material, usually porcelain or glass. It is thought to be the earliest developed overhead insulator and is still popularly used in power networks up to 33 KV. Single or multiple pin insulators can be used on one physical support, however, the number of insulators used depends upon the application's voltage. Pin insulators are one of three types of overhead insulators, the others being strain insulators and suspension insulators. Unlike the others, pin insulators are directly connected to the physical support compared to being suspended from the wire. Pin insulators are shaped to allow the secure attachment of the conducting wire and avoid it coming adrift. The wire is usually attached to the insulator by being wrapped around it or in other circumstances, fixed into grooves on the insulator itself. When an insulator is wet, its outer surface becomes conductive making the insulator less effective. An insulator has an umbrella-like design so that it can protect the lower part of the insulator from rain. To keep the inner side of the insulator dry, ridges around the insulator, "rain sheds", are made. These increase the creepage distance from the energized wire to the mounting pin.