Comment by MisterTea
4 months ago
> So how did we get to a point where one component can hold trillion-dollar industries hostage? Turns out, a quirk of history made the entire world’s electricity systems reliant on transformers.
> At the end of the 19th century, when electricity was just starting to become a commercial source of energy, two businessmen fought to control its future in what came to be known as “the war of the currents.” Thomas Edison promoted the use of direct current (DC) and George Westinghouse, inventor and industrialist, was convinced that alternating current (AC) would prove more practical.
> In a clash of personality, finance and some genuine technical advantages, Westinghouse won out and the world has been mostly stuck with using AC as a means of generating and transmitting electricity. Transformers are necessary to make the AC system work.
This entire section is a glaring load of nonsense and needs to be removed. We had to start with AC for a variety of technical reasons, the main one being that boosting DC voltage pre-switching technology was impossible. DC cant pass through a transformer unless it is converted to some form of AC, usually in the form of PWM square waves these days. Before the invention of the mercury arc rectifier (And later valve) in 1902 you had boost DC using mechanical methods: generators. The problem there is physical, they did not have the ability to insulate the generator windings at high voltage potentials. They also had problems with DC voltages over 2000 volts on commutators [1] citing excessive arcing. Commutators are also a limiting factor in machine size as beyond several MW they dissipate too much power. So with all this the highest practical voltage for a DC grid using early electrical machinery is around 2 kV. Now imagine all that mechanical complexity on the distribution end. Meanwhile, early AC transmission was already in the tens of kilovolts: 11/22/33 kV (multiples of the early Edison 110 volt standard.)
As for the whole war of currents, I feel it is vastly overstated and was more a public spectacle than serious scientific dispute. It was already known from early on that AC was the future thanks to its ability to easily be transformed to higher voltages for transmission and back again with no moving parts. The "war" was likely Edison marketing to sell off the remaining inventory less desirable DC machinery.
Yes this is the most glaring issue. There also two disconnects later in the article: at the end it laments how china has been increasing transformer manufacturing but the US government has done nothing. Then in the next sentence its mentions trumps tariffs have increased transformer costs, I. E. Government action to increase domestic production. It also glosses over the new DOE rule on how transformers are made…so maybe there is a larger story there relevant to the lack of supply.
Tariffs don't help onshore manufacturing when they apply to the materials that the manufacturing needs and might evaporate before the manufacturing capability is actually created. Tariffs needs to be applied carefully and consistently to actually encourage this.
Sure, I’m just saying the article was pretty long but pretty short and declarative on the impact of tariffs. Earlier in the article for example is said there was still a factory in the US where the magnetic core material was made.
We had targeted policies under Biden to increase US production of grid components. This entailed invoking the DPA and setting aside millions for manufacturing improvements. Trump paused all that and created blanket tariffs that don’t seem like they’re designed to onshore US manufacturing of these very specific components but do increase all the material costs. This is not an easy thing to fix with dumb tariffs, and it’s really easy to make everything worse.
I’m just noting the article doesn’t have anything specific of value to say about tariff’s. This is not directed at you but rather the reporters: I can read general opinions on tariffs or political parties anywhere; I need details relevant to transformers here to not just ignore other opinions
Also it is quite a leap to the conclusion that HVDC eqipment will not have long lead times as well especially since there are quite a few less companies making it.
> practical voltage for a DC grid using early electrical machinery is around 2 kV.
What is a current (pun!) practical limit?
If a 100MW PV farm and a data center are separated by 1km (20 Olympic pools) - is there a way to avoid AC?
I know there are future solutions [1]
[1] https://techcrunch.com/2025/04/07/former-tesla-exec-drew-bag...
The early limit was because high voltage DC required producing it at the generator, whereas you could produce high voltage AC by generating at a lower voltage and then stepping it up with a transformer for long distance transmission.
The rules are changing because of switchmode voltage conversion, using transistors to switch the voltage at a high frequency, where the magnetics (transformers, inductors) can be much smaller and more efficient, then converting back to DC. This is how virtually all smaller power supplies have been made for years, the only question (which I don't know) being how far along we are at reaching the voltage levels of long distance transmission in this way.
I'd think that hustling us towards DC with electronic voltage conversion would be a reasonable strategic goal for dealing with the transformer problem, worthy of support by a government.
HVDC and UHVDC are used extensively for long distance transmission, notably for undersea cables and in China, which has made massive R&D investments in the technology in order to shift energy from West to East. Large solar, wind and hydro in the West.
However, DC does not make sense for a radial power distribution network. The article is propagating nonsense.
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That link talks about 5MW 35kv AC / 800v DC converters.. completely different thing, they try to sell a single-source PV invertor-to-35KV AC solution first, then 35KV to 800V DC second, to have a sorta complete solution of PV-to-datacenter. And it's only 5MW. And only 35KV AC. For moving 100MW even over a few km you would need 110KV at least. I think. An overhead wire can handle about 600A of current, that's the physical limit and the reason for kilovolts there.
Consider also that there is nothing existing in transmission and switching gear certified for HVDC it being rare one-off projects so far, while AC is ubiquitious, more-or-less mass-produced and many people are trained in its maintenance.
> If a 100MW PV farm and a data center are separated by 1km (20 Olympic pools) - is there a way to avoid AC?
Not in any economical sort of way. A rectifier and two transformers is cheaper than directly switching HVDC. If you step up the voltage to 115kV, a 100MW three-phase AC circuit is only 500 amps.
HVDC transmission over 100kV lines are common now. https://www.emeranl.com/maritime-link/overview
Yup. The only thing missing from the writeup is a eulogy for the death of the rotary converter.
I mean if you wanna leapfrog china just throw more money into switched mode inverters and rectifiers. You don't have to use transformers. As long as you have a black cheque, there are plenty of options.
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