For the safety of anyone who might come into contact with a transformer, regulations require that all terminals be placed out of reach. Additionally, unless the bushings are rated for outdoor use—like top-mounted bushings—they must also be enclosed. Having the substation bushings covered keeps water and debris away from the live components. The three most common types of substation bushing enclosures are flange, throat, and air terminal chamber.
Flange
Flanges are typically used as just a mating section to bolt on an air terminal chamber or another transitional section. As pictured below, the transformer can be outfitted with a full-length flange (left) or a partial-length flange (right), which provides an interface on which you can bolt either a transition section or a bus duct.
Throat
A throat is basically an extended flange, and as you can see in the image below, it can also connect directly to a bus duct or a piece of switchgear, just like a flange. Throats are usually located on the low-voltage side of a transformer. These are used when you need to connect a hard bus directly to the spades.
Air Terminal Chamber
Air terminal chambers (ATCs) are used for cable connections. They provide more space than throats do, since they need to bring in the cables to attach to the bushings. As illustrated in the image below, ATCs can be either partial-length (left) or full-length (right).
Post time: Sep-11-2024