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Beyond Efficiency in Grid Power Transformers

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Larry Rebman's picture

It is estimated that 25% of an organization's assets are or will become surplus during thier useful life. EMLS is the vehicle by which this value is recovered by the utility owners of surplus...

  • Member since 2011
  • 4 items added with 1,033 views
  • Mar 29, 2023

Evaluating power transformer proposals is usually limited to first cost and efficiency calculations, yielding a total cost of ownership over the” expected life” of the transformer.  This calculation is rendered meaningless if premature failure or high maintenance costs are incurred.  Additional insight into what is being proposed is needed to ensure long asset life and stem the "race to the bottom" in value being driven in the industry by so-called low evaluated price purchases.

What really determines the expected life is the field stress analysis derived during the design review.   Field stress calculations tell the expected performance of insulating media (both hard and liquid) to achieve electrical performance.  They are the basis of  the manufacturer's cost calculation and design philosophy, because modeling allows value-engineered minimums to reduce first cost of manufacture.  Higher stresses can degrade insulation and oil quality, cause gassing, increase oil processing interval, reduce resiliency to grid events.

Large grid power transformers must be designed to generate a price proposal.  By requesting field stress calculations, in addition to eficiency and first cost, your grid wil be more reliable and resilient.  Transformers are the longest lead time, most expensive and critical asset in power transmission. This simple addition to your specification helps ensure the best value.

Matt Chester's picture
Matt Chester on Mar 29, 2023

Would you say this evaluation has only gotten more important in recent years with the supply chain for new transformers becoming as strained as they are? 

Larry Rebman's picture
Larry Rebman on May 10, 2023

This evaluation presents one of the clearest indicators of value. Standards have addressed efficiency, mechanical strength, manufacturing accuracy and expected life. But there are no standards as to insulation stress, beyond a transformer's ability to pass factory acceptance tests. When value engineering was adopted by manufacturers it was with an eye towards market competition on price. If purchasing a better built transformer keeps the buyer from premature replacement, then it is especially important to do so in this supply challenged market. 

Larry Rebman's picture
Thank Larry for the Post!
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