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The Hitachi Energy type DTU is a modular, linear-action, bridging-type, de-energized tap-changer design available with a current rating of up to 500 A per deck and up to 650 kV BIL. The standard number of positions is five, with seven positions available in certain winding configurations. The DTU system includes a choice of standard operating mechanisms, drive shafts, shields, and barriers needed for the basic configurations required for either single or double deck per phase applications. The DTU tap changer uses silver-plated moving contacts to bridge between two of the stationary copper contacts to make a tap connection. The moving contacts are driven by a linear Geneva gear that is connected via steel shafts to the external operating mechanism. The operating mechanism includes a position indicator and provisions for padlocking. Special designs are available for dual voltage or delta-wye applications.

Product scope

  • Maximum rated through-current: 1,500 A (500 A per deck)
  • Highest rated lightning impulse / power frequency withstand to earth: 650 kV / 275 kV
  • Lightning impulse / power frequency withstand between adjacent contacts: 650 kV / 275 kV
  • Maximum number of operating positions: 7

Why Hitachi Energy?

  • The DTU tap-changer saves space within the transformer
  • The DTU tap-changer mounts in the cusp of the transformer winding
  • Simple operating mechanism brought out of the transformer at ground level

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