page_title: Distribution transformer
section_title: Types
hierarchical_section_title: Distribution transformer / Types
caption_attribution_description: English: Two three-phase pylon-mounted transformers in Budakeszi, Hungary
context_page_description: A distribution transformer or service transformer is a transformer that provides the final voltage transformation in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer.
  The invention of a practical efficient transformer made AC power distribution feasible; a system using distribution transformers was demonstrated as early as 1882.
  If mounted on a utility pole, they are called pole-mount transformers. If the distribution lines are located at ground level or underground, distribution transformers are mounted on concrete pads and locked in steel cases, thus known as distribution tap pad-mount transformers.
  Distribution transformers normally have ratings less than 200 kVA, although some national standards can allow for units up to 5000 kVA to be described as distribution transformers. Since distribution transformers are energized for 24 hours a day, reducing iron losses has an important role in their design. As they usually don't operate at full load, they are designed to have maximum efficiency at lower loads.
context_section_description: Distribution transformers are classified into different categories based on factors such as:
  Mounting location – pole, pad, underground vault
  Type of insulation – liquid-immersed or dry-type
  Number of phases – single-phase or three-phase
  Voltage class
  Basic impulse insulation level (BIL).
caption: Two three-phase transformers in Hungary
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