Buchas ANSI

Transformer bushings are the main insulation devices outside the transformer tank. They are used to bring the transformer winding leads from inside the oil tank to the outside, while also providing insulation between the leads and the ground and holding the leads in place.  

Common types:  

– Pure porcelain bushing: Mostly used for 10kV and below, the porcelain sleeve has air insulation inside.  

– Oil-filled bushing: Mostly used for 35kV level, the porcelain sleeve is filled with oil, and the copper rod is wrapped with insulating paper.  

– Capacitor bushing: Used for high voltage above 100kV, made of an oil-paper capacitor core, porcelain parts, oil reservoir, spring, etc., with the main insulation being the capacitor core.  

Main functions:  

– Electrical insulation: Prevents electrical breakdown between the lead and the transformer casing, oil tank, or other grounded parts.  

– Mechanical support: Supports and holds the lead in place, preventing it from loosening or getting damaged during operation.  

– Current-carrying path: Conducts load current during normal operation and withstands short-circuit current during faults.  

– Sealing protection: Fully sealed structure prevents internal insulation from moisture or contamination, extending its lifespan.  

Aplicações:  

– Distribution transformers: Mostly use pure porcelain or resin bushings.  

– Medium/high voltage transformers: Mostly use oil-filled or capacitor bushings.  – Special requirements: Can integrate a current transformer (bushing CT) for measurement and protection.