An Auto transformer is a/an:

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Question

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ALP CBT 2 Electrician Previous Paper: Held on 23 Jan 2019 Shift 1

Answer 1

Autotransformer:

An Autotransformer is a variable output voltage transformer.
An autotransformer is a kind of transformer where primary and secondary share the same common single winding.
In an autotransformer, energy transforms taking place through both conduction and induction.
It works as a variable transformer.
This type of variable autotransformer is generally used in laboratories and science labs in schools and colleges.
It is commonly known as Variac.

Important Points

Advantages of auto-transformer over a two-winding transformer:

More efficient for the same VA rating
Smaller in size
Require less copper in their construction
Cost is less compared to double wound transformers of the same VA rating
Core and copper losses are lower due to less resistance and leakage reactance giving a superior voltage regulation than the equivalent two winding transformer