The following kinds of transformers are the most important ones:
- Power transformers. For the transmission and distribution of electric power.
- Auto-transformers. For converting voltages within relatively small limits to connect power systems of different voltages, to start AC. motors etc.
- Transformer for feed installations with static convertors. (Mercury are rectifiers, ignitrons, semi-conductor valves, etc.) When converting A C. into D. C. (rectifying) and converting D.C. into A C. (inverting).
- Testing transformers. For conducting tests at high and ultra-high voltages.
- Power transformers for special applications. Furnace, welding etc.
- Radio-transformers. It is used in radio engineering etc.
Note. Distribution transformers should be designed to have maximum efficiency at a load much lower than full-load (about 50 per cent).
Power transformers should be designed to have maximum efficiency at or near full-load.