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Substation autotransformers transfer the incoming high-voltage to the next lower voltage level. As an example, an incoming high-voltage of 400 kV would be transferred down to 220 kV.

In general, substation autotransformers are equipped with on-load tap-changers (OLTC). Incoming transmission lines are connected to the transformers through bushings and cables through cable boxes and cable sealing ends.

Autotransformers are built in core form with auto-connected windings, i.e., common main winding and a separate low-voltage winding.


Product scope:

  • Ratings up to 1,300 MVA (sometimes higher ratings are required)
  • Primary voltage up to 765 kV and higher
  • Secondary voltage is generally ≤ 230kV or higher, depending on the grid configuration
  • Load tap changers are generally required
  • Single or three-phase

Why Hitachi Energy core intertie transformers

  • Our track record of 1,400+ units delivered since 1995
  • Short-circuit performance at twice the industry standard
  • Proven track record in meeting customer performance requirements (ask for our test floor failure statistics)
  • 12 factories, one global approach – bringing consistency, delivery performance, and technology

Why Hitachi Energy shell intertie transformers

  • Design technology eliminates the risk of a hot spot
  • Outstanding thermal performance resulting from directed oil flow, minimization of losses, and control of the hot spot
Substation autotransformers
power plant engineer for substation

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