Which of the following is the main advantage of an autotransformer over a two winding transformer?
Right Answer is:
Copper losses are negligible
An autotransformer is a type of transformer that uses a single tapped winding rather than the two separate and electrically isolated windings used by mutual transformers. Because autotransformers don’t have separate windings, unlike mutual transformers there is no electrical isolation between the primary and secondary circuits.
- Therefore the primary is electrically connected to the secondary, as well as magnetically coupled to it.
- The alternating current applied between the input points will induce a flow of magnetic flux around the core.
- This magnetic flux will link with all the turns forming the coil, inducing a voltage into each turn of the winding.
- Since the volts-per-turn is the same in both windings, each develops a voltage in proportion to its number of turns.
- In an autotransformer, part of the current flows directly from the input to the output, and only that part is transferred.
Where electrical isolation between the primary and secondary windings is unimportant, the use of an autotransformer has a number of advantages over a mutual transformer.
- As we know that, the saving of copper in auto-transformer is “K” times the copper required in the 2-winding transformer. Hence less copper is required in the case of an auto-transformer.
- As less copper is required, hence less ohmic losses and core losses will occur. Correspondingly the efficiency of an auto-transformer is higher than the efficiency of a 2-winding transformer.
- Leakage reactance is less in the case of an auto-transformer, hence it has superior voltage regulation.
- Due to single winding, less weight as well as less space will be there.
- There are no secondary copper losses, so autotransformers are more efficient than a corresponding mutual transformer.