DTU de-energized tap changer

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 copper stationary 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.

• 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

• 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