Bushings
A bushing is the insulated connection between a transformer and the line. The public lead-time figure below is the one the 2022 supply-chain review states.
Compiled . Dates on each claim are the dates of the linked sources.
What it is
The review says bushings provide the electrical connection between a transformer and the electrical transmission network. It says industry engagement indicated that the most common bushing for large power transformers is the oil-impregnated paper bushing, typically a porcelain air-side insulator, a conductor of copper or aluminum, insulating kraft paper, and mineral oil. U.S. Department of Energy Electric Grid Supply Chain Review .
Why it constrains supply
The review says high-voltage bushings often have a long lead time of up to five months, citing a 2014 Department of Energy report for that figure. It says industry engagement and literature review indicated only a few domestic bushing suppliers. This page does not repeat the company names in that list. U.S. Department of Energy Electric Grid Supply Chain Review .
The review’s quantitative assessment says bushing risk scores come mostly from high import reliance and long lead time. It says that when an end user asks for porcelain for bushings to be sourced outside China, the limited sources it names are the United States, Japan, and Poland. U.S. Department of Energy Electric Grid Supply Chain Review .
Current public evidence
The five-month bushing lead time, the count of domestic suppliers as “a few,” and the porcelain sourcing limit are the bushing supply figures the February 2022 review states. It does not publish a later week count for bushings. U.S. Department of Energy Electric Grid Supply Chain Review .
Buyer mitigations
The same review says manufacture of a large power transformer takes 12 to 16 weeks on average only if all the materials are available. A bushing lead time of up to five months, as that review states it, sits on the clock before that manufacture interval can start. 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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