Power Transformer: Learn the Purpose, Cost, and Lead Time to Procure

Power Transformer
Power Transformer

Purpose of transformer

Transformers are designed to do one of the following:

  • Step-up voltage; consequently step-down current – enables long-distance transmission by reducing I^2\times R copper losses. Step-ups are found near generating stations.
Step up transformers at a generating station
Step up transformers at a generating station – three transformers and one spare shown.
Step up transformer at the base of a wind turbine.
Step up transformer at the base of a wind turbine. Each turbine gets its own. Image credit: Patrick Finnegan – CC.
  • Step-down voltage; consequently step-up current – enables distribution of power to customers at a safe voltage magnitude. Step-downs are found near load centers and in sub-transmission systems.
Step down transformers at a distribution station
Step down transformers at a distribution station
  • On distribution transformers, when equipped, the load tap changer keeps the secondary voltage constant as the load increases or decreases.
  • Transformer are also designed for special applications such as phase shifting transformer (pushes more power on a t-line by varying power-angle \sin\deltalearn more), HVDC converter transformer, SVC transformer, grounding zig-zag transformer etc.

Cost of transformer

The cost of a power transformer varies significantly based on BIL rating, MVA rating, core design, guaranteed losses requirement, tank design, etc. The prices listed below are for a standard design transformer.

  • Small power transformer with LTC ~10MVA or lower: ~ $600,000
  • Medium power transformer with LTC ~50MVA or lower: ~$1,400,000
  • Large power transformer ~300MVA or lower: ~ $3,500,000
  • Large phase shifting speciality transformer: ~$5,000,000

Lead time to procure transformer

~ 1 year, regardless of MVA rating.

Information on cost and lead-time are rough estimates — contact vendor with your equipment specifications for actual figures.


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Substation Major Equipment

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For which event should a surge arrester operate? Check all that apply.
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An industrial facility is plagued with voltage flicker and poor power factor at the service entrance. Which device would you install to fix both issues?
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You are building an interconnect station, tying wind farm generation to the power grid. At the substation, the sources are tied through a tie-breaker. Which device would you install to make sure the sources are synchronized?
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Which combination of devices would you use to implement power line carrier?
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A transformer develops an internal fault. Which device would you install on the transformer high-side to interrupt fault current?
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What’s the purpose of a conventional power transformer?
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In a distribution substation, the available ground-fault current on the low side of the step-down transformer is excessive, over-dutying the switching equipment. What is your cost-effective solution to reducing the fault current?
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