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8. Comprehend the principle of auto-transformer.

8.3. List the advantages and disadvantages of auto-transformer.

ADVANTAGES OF AUTO TRANSFORMER

  • Less costly
  • Better regulation
  • Low losses as compared to ordinary two winding transformer of the same rating.

DISADVANTAGES OF AUTO TRANSFORMER

There are various advantages of the auto transformer, but then also one major disadvantage, why auto transformer is not widely used, is that

  • The secondary winding is not insulated from the primary winding.
    If an auto transformer is used to supply low voltage from a high voltage and there is a break in the secondary winding, the full primary voltage comes across the secondary terminal which is dangerous to the operator and the equipment. So the auto transformer should not be used for interconnecting high voltage and low voltage systems.
  • Used only in the limited places where a slight variation of the output voltage from input voltage is required.

APPLICATIONS OF AUTO TRANSFORMER

  • It is used as a starter to give up to 50 to 60% of full voltage to the stator of a squirrel cage induction motor during starting.
  • It is used to give a small boost to a distribution cable, to correct the voltage drop.
  • It is also used as a voltage regulator
  • Used in power transmission and distribution system and also in the audio system and railways.


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