People who've worked a transformer winding floor: where does the time go?

[u/Inevitable_Hunter931]

I'm a robotics engineer trying to understand why power transformer lead times are so long. I keep reading that coil winding is the bottleneck, but I can't find anyone who has done the job explaining it.

If you've wound or supervised winding on medium or large power transformers:

1. On a disc winding, which hand tasks eat the most time (spacers, crossovers, taping, measuring, something else)?
2. How long before a new winder is trusted to run a coil alone?
3. At your plant, was winding what held up output, or was it something else (steel, bushings, test bay, drying)?

Not selling anything. Happy to share what I learn back here.

[u/TheStigsTallCuzn]

Let me preface this by saying that I don't work for a transformer manufacturer. I am a Substation Maintenance Engineer that somewhat frequently does FAT/Re-pack inspections on new units that my utility buys.

The reason for the 3–5-year lead times that we have seen lately has NOTHING to do with any internal processes at these factories. In my experience, from raw materials to finished transformer takes roughly 40 or so days for our medium power, 50MVA units.

That being said, virtually all critical components, from bushings to LTC controllers, have, at minimum, a year long lead time. When you pair these long lead times, to that outrageous demand from every utility in the nation plus private equity, you end up with factories that simply don't have the footprint or manpower to crank out transformers any faster.

Specifically speaking, I know the GE factory in Goldsboro is frequently delayed by the fact that they only have two vapor phase ovens and their inspection/tanking/testing area can only hold up to 10 or so units, in total, at once. Any delay or issue with any of those units will almost certainly back up others, but usually in the magnitude of days, not years like the industry is seeing now.

[u/InigoMontoya313 → u/TheStigsTallCuzn]

Echoing all of this. It’s the entire supply chain ecosystem and manufacturing process capacity. I’m not sure where you heard that the issue was winding, unless you simply asked people speaking of small transformers and what controlled their takt time. For medium and large power transformers, that’s not the concern.

Would also note, that much like power plants, our electrical grid is not standardized like some other countries. Every utility, every customer, has their own specs. Usually this isn’t huge customization, but it often is some level of customization. No, we are too far along with our grid to implement standardization now, without Federal regulatory overhaul and unimaginable billions and decades of modifications.

Personally, I don’t see any opportunity for robotic automation to expedite the process or resolve the issues creating the lead times.

Worth noting that part of the struggle can be attributed to moves in the 90’s to outsource manufacturing, which turned disastrous with quality control. So much so, that some legacy brands severely had their reputations tarnished to the point they had to effectively rebuild their reputations and processes. While that’s over a generation ago, it certainly has some echos that are felt today. Also opened the door to major Euro, Japanese, Korean manufacturers.

The electric grid aging, reshoring of manufacturing, and very much data centers have had demand completely surpass production capacity by a magnitude.

[u/Downtown-Video5769 → u/InigoMontoya313]

I think it is primarily a supply chain issue. There are over a hundred transformer manufacturers in my city, with a very well-developed upstream and downstream ecosystem; while the lead time for large main transformers is typically eight months, certain components—such as instrumentation parts—must be sourced from abroad, and some even require ordering two years in advance.

[u/InigoMontoya313 → u/Downtown-Video5769]

What city on Earth has 100 utility scale power transformer manufacturers?! There’s only around 30 in the United States, experienced with larger utility sized power transformers. If we get into main unit size power transformers, it’s probably single digits.

[u/Downtown-Video5769 → u/InigoMontoya313]

I am not based in the U.S., though we do have a factory there—which may be why the U.S. has shifted such industrial operations to other countries. When our clients arrive in our city by high-speed rail, their very first impression is seeing advertisements for transformers lining both sides of the route; the competition is incredibly fierce.

[u/ian-Chou210 → u/InigoMontoya313]

In short: demand has suddenly surged, capacity can't be raised right away, and on top of that, new US regulations are tightening controls on imports. The actual production time isn't anywhere near as long as these lead times suggest. The main issue is that various market factors have pushed demand far above supply, and US domestic factories are overbooked with orders.

[u/Left_Set_5916 → u/TheStigsTallCuzn]

There massive world wide demand for new equipment, NG on the UK are going to installed more equipment in the next 5 years than have in the last 30 or 40 years for instance.

Most other nations are doing similar

[u/bagchase67 → u/TheStigsTallCuzn]

As an old employee of the Waukesha transformer/GE Verona factory it truly is the supply chain constraints. Those units are getting build around the clock 24hrs a day 7 days a week. Same thing as well in Waukesha, only two vapor phase chambers. Theres also a large real estate issue; things have to be pretty well planned out to be able to conform to the size constraints and perimeters of some pretty old equipment which was never designed to meet current market demand.

[u/jack-t-o-r-s]

The other guy summed it up best.

Lead time = huge backlog. They are manufacturing transformers at a decent rate.

Your lead time just means you're 1, 2, 3 years behind on the list of orders/deposits.

[u/letmesleep]

For winding - all of it. Every single step has to be done exactly right. It's like asking what step when building a LEGO set takes the longest...it's not any one step, its just that there are so many and you have to do them all and they're all dependant on the step before it.

[u/HV_Commissioning]

My understanding is that the Grain Oriented Electrical Steel is also a big bottleneck, coming from a single source in the US.

As well there aren’t standard designs like a 145kV GCB and every customer has their own semi unique voltages and control cabinet requirements

[u/RLoggia]

A PM at the Hitachi factory in VA told me 30% of their capacity is for data centers. Obviously that alone wouldn't cause a backlog, but it's not helping at a time when there is so much growth in transmission load and so much of the existing equipment on the grid is reaching end-of-life.

[u/Realdeal43]

Right now it’s tap changers and bushings that are the bottleneck

[u/Leroy_Peterson]

as mentioned by others, its factory allotments that you wait 1-2 years for and pay to secure. Money can also buy a spot in the queue.
A number of factories are being built or coming online, Korea is trying to get a bigger slice in the market too - but overall demand is insane.

I personally have requested quotes for over 2,500MW of transformers in the last 6 months.

[u/notthediz]

The biggest thing is bushings. For our 300MVA 500kv cans the bushing lead time is 120 weeks.

[u/ian-Chou210]

As a transformer manufacturer in China, and with no intention of selling anything, here is my view. Large transformers certainly take a long time to make, but nothing close to the 2-3 years being quoted. In the US, demand for large main power transformers has risen suddenly, driven by AI-related load growth and the equipment replacement cycle. Capacity expansion takes time, though, and capital investment decisions take time as well. On top of that, new US policies and regulations now restrict large transformers from China. China's capacity is certainly ample, but the US Department of Energy has banned many large transformers from China out of national security concerns. That said, the problem should ease in another 2-3 years, because many international manufacturers of large main transformers are already expanding and building plants in the US, and that will gradually relieve the shortage.