- Bushing (electrical)
A bushing is an
electrical engineering component that insulates ahigh voltage conductor passing through a metal enclosure. Bushings appear onswitchgear ,transformer s,circuit breaker s and other high voltage equipment.Description
The bushing is hollow, allowing a conductor to pass along its centre and connect at both ends to other equipment.Bushings are often made of wet-process fired
porcelain , and may be coated with a semi-conducting glaze to assist in equalizing the electrical stress along the length of the bushing.The inside of the bushing may contain paper insulation and the bushing is often filled with oil to provide additional insulation. Bushings for medium-voltage and low-voltage apparatus may be made of resins reinforced with paper. The use of
polymer bushings for high voltage applications is becoming more common. The largest high-voltage bushings made are usually associated with high-voltage direct-current converters.Capacitor types
Some of the higher voltage types (layers of paper, film and aluminum coil used as insulating medium) are called
capacitor bushings because they form a low value capacitor between the conductor and the wall. This is done to reduce theelectrical field stress that would otherwise occur and cause breakdown.Bushing failure
Bushings sometimes fail due to
partial discharge degradation in the insulation. There is at present great interest in the electricity supply industry in monitoring the condition of high voltage bushings.ee also
In
mechanical engineering , abushing orPlain_bearing refers to a part which allows a rotating component to pass through a stationary one, the bushing carrying the load.References
*cite book | author=Central Electricity Generating Board | title=Modern Power Station Practice |publisher=Pergamon | year=1982 | id=ISBN 0-08-016436-6
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