Copper and conductors
Public supply reviews separate continuously transposed copper, used in large power transformer windings, from ordinary copper sheet. Figures below are copied from those sources.
Compiled . Dates on each claim are the dates of the linked sources.
What it is
The review describes continuously transposed copper, abbreviated CTC, as a specialized copper wire used for transformer coil winding to minimize losses and hot-spot temperatures, and says it enables compact winding with improved short-circuit performance. U.S. Department of Energy Electric Grid Supply Chain Review .
A 2020 Department of Commerce industry survey, as cited in the report, found that GOES and CTC each account for roughly 25 percent of final large power transformer production costs. U.S. Department of Energy Report to Congress .
Why it constrains supply
The review’s quantitative assessment says CTC’s highest supply-chain risk is the lack of a substitute for large power transformer manufacturing. It ranks regular copper and insulating materials at the lowest risk, and it says the pandemic lengthened lead times for every material it considered. U.S. Department of Energy Electric Grid Supply Chain Review .
The report says delays may occur when a manufacturer has difficulty obtaining specialty copper wire, specialty steel laminations, or appropriately skilled labor, and that CTC copper wire is one of the raw materials with a significant impact on large power transformer availability and price. U.S. Department of Energy Report to Congress .
Current public evidence
Stakeholders cited in the review gave lead-time comparisons before and after COVID-19 of 8 weeks versus 18 weeks for CTC, and 4 weeks versus 12 weeks for regular copper sheet. U.S. Department of Energy Electric Grid Supply Chain Review .
The Office of Electricity page says lead times for transformer orders, particularly distribution transformers, increased from three to six months in 2019 to 12 to 30 months in 2023, and names copper among the materials shortages. Those months are order times for transformers, not a copper week count. U.S. Department of Energy Office of Electricity .
Buyer mitigations
The review says that, on average, it takes 12 to 16 weeks to manufacture a large power transformer if all the materials are available, then one week to test and one week to prepare the unit for shipping. The manufacture interval in that sentence starts only when the materials are already available. U.S. Department of Energy Electric Grid Supply Chain Review .
Ordering timelines that public sources state are collected in the buying guide. Typical lead times by class and region are on the grid lead-time tracker. Mid-tier manufacturers already in the directory are on the mid-tier list. A dash on that list means no public dated capacity note is on file.
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