Transformers can be classified on different basis, like types of construction, types of cooling etc.
(1) on the basis of construction:-transformers can be classified into two types as;
- core type transformer
- shell type transformer
Use of core type transformer
In the core type transformer, the roll is a cylindrical scar, which is mounted on the limbs of the core as shown in the above figure. cylindrical coils have different layers and each layer is insulated from each other. materials such as paper, cloth or mica can be used for isolation. Low voltage reels are placed closer to the core, as they are easier to isolate.
shell type transformer
The coils are scarred and mounted in layers that are stacked with insulation between them. a shell type transformer may have a simple rectangular shape or may have a distributed form.
(2) on the basis of their purpose
- Step up transformer: voltage increases (with subsequent decrease in current) at secondary.
- Step down transformer: voltage decreases (with subsequent increase in current) at secondary.
(3) on the basis of type of supply
- Single phase transformer
- Three phase transformer
(4) on the basis of their use
- Power transformer: used in transmission network, high rating
- Distribution transformer: used in distribution network, comparatively lower rating than that of power transformers.
- Instrument transformer: used in relay and protection purpose in different instruments in industries
- current transformer (ct)
- Potential transformer (pt)
(5) on the basis of cooling employed
- Oil-filled self cooled type
- Oil-filled water cooled type
- Air blast type (air cooled)