20th September 2020

Difference between a Power Transformer and Distribution Transformer

Power Transformer

  • Commonly used for transmitting power by stepping up and stepping down, ideally application above or equal to 33 kV i.e 765 kV, 400 kV, 200 kV, 110 kV, 66 kV and 33kV.
  • In distribution transformer, stepping up and stepping down action is done.
  • The application of power transformers is in transmission and receiving station.
  • Load fluctuation is very low as they are not directly connected to load.
  • Commonly operated at 90% to100% load.
  • A power transformer is designed in such a way that better efficiency at full load is obtained.
  • In Power Transformer, the flux density is higher than the distribution transformer.
  • Tap changer is not applicable in case of a power transformer.
  • Size of the power transformer is huge as compared with the distribution transformers.
  • Power transformers, primary winding always connected in star or Delta and secondary winding in delta connections. At the end of the transmission line, the primary winding connected in star and secondary winding in delta connections. while at the beginning of the transmission line the primary winding connected in delta and secondary winding in star connections.
Distribution Transformer
Transformer

Distribution Transformer

  • Commonly used for distributing power by stepping down, ideally application below 33 kV i.e 11 kV, 6.6 kV, 3.3 kV, 415 V and 220 V.
  • In distribution transformer only stepping down action are done. stepping up of voltage action is not required as the power is distributed to downstream by stepping down the voltage.
  • Distribution transformer is used in only in distribution application.
  • Load fluctuation is high as they are directly connected to load.
  • Commonly operated at 95% to70% load
  • Distribution transformer is designed to achive better efficiency even at 50% – 70% load.
  • In distribution transformer, the flux density is higher than the distribution transformer.
  • Tap changer is applicable in case of a distribution transformer.
  • Size of the distribution transformer is small as compared with the power transformers
  • Distribution transformer, primary winding always connected in Delta and secondary winding in star connections.

Relevant article: Transformer Cooling Technique

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