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Data centers are transitioning from AC to DC

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Re: Data centers are transitioning from AC to DC

#101

Post by bigiain »

jacquesm wrote: post #94
bigiain wrote: post #85

Earlier quoted context omitted.

Well, it'd still vaporise, but it'd sound smoother and more musical as it did it, and the soundstage from the plasma arc would be _stunning!_

It's almost worth the experiment and your cables are a sacrifice I'm willing to make. For science, of course.

You're _so_ right!

I'm pretty sure you have my delivery address from when I bought sorted Lego from you about 10 years back.

Let me know when to expect the 100,000Amp test equipment!

I shall make sure I wear better PPE than just my reading glasses.

:-)

Re: Data centers are transitioning from AC to DC

#102

Post by manwe150 »

arijun wrote: post #38
adgjlsfhk1 wrote: post #19

Earlier quoted context omitted.

AC is less efficient than DC at a given voltage. The advantage of AC is that voltage switching is cheap, easy and efficient. Switching DC voltage is way harder, more expensive, and less efficient. However the switching costs are O(1) and the transmission losses are O(n) so for some distance (currently somewhere around 500 km) it's worth paying the switching cost to get super high voltage DC. The big thing that's chan…

> AC is less efficient than DC at a given voltage To expand on this, a given power line can only take a set maximum current and voltage before it becomes a problem. DC can stay at this maximum voltage constantly, while AC spends time going to zero voltage and back, so it's delivering less power on the same line.

That’s true, but my understanding is the main contributor is skin effect, since AC travels only on the surface of the wire, while DC uses the whole area, resulting in lower resistance loss (https://en.wikipedia.org/wiki/Skin_effect)

Re: Data centers are transitioning from AC to DC

#103

Post by bigiain »

jacquesm wrote: post #96
bigiain wrote: post #79

Earlier quoted context omitted.

Yep. Super super lucky. I suspect my reading glasses are the only reason I can still see anything.

I have a couple of those narrow escapes one of which led me to put a significant chunk of Eastern Amsterdam out of power. Another involved Beryllium oxide. 9 lives are barely enough.

I would read that book...

Re: Data centers are transitioning from AC to DC

#104

Post by chrneu »

hristov wrote: post #9

It is absolutely stupid to talk about this as edisons revenge. If Tesla had the modern high power transistors needed to get high voltage dc out of the ac produced from a spinning turbine he would be all for high voltage dc too. Tesla understood that high voltage was needed for efficient long range transmission. He also understood that transformers were the inly remotely efficient way to climb up to and down from thes…

the internet really needs to stfu about tesla and get over that oatmeal comic that spawned a billion internet myths. dude was a decent inventor but suffered from chronic mental health issues and, in his lifetime, wasted so much time/energy/money and burned so many bridges with his horrible attitude. there's a reason most people didnt like him in his day, he was a depressed asshole who alienated everyone around him, and yes I know he was likely gay in a time when that wasn't cool. the fact still remains; his inventions are massively overblown by internet nerds.

the podcaster Sebastian Major from "Our Fake History" did a looonnngg patreon episode on tesla and debunked most of the weird myths around tesla. Sebastian doesn't have a vendetta or anything, it's just amazing how much of the Tesla stuff is just nonsense or is viewed through a very weird bias nowadays. Major also briefly touches on the weird Edison stuff and how the internet has twisted Edison into a villain.

Re: Data centers are transitioning from AC to DC

#105

Post by topspin »

sghiassy wrote: post #13

I’ve always wondered about these new High-Voltage DC (HVDC) transmission lines. I always thought AC’s primary benefit was its transmission efficiency?? Would love to learn if anyone knows more about this

> I always thought AC’s primary benefit was its transmission efficiency??

There are many factors involved, and "efficiency" is only one. Cost is the real driver, as with everything.

AC is effective when you need to step down frequently. Think transformers on poles everywhere. Stepping down AC using transformers means you can use smaller, cheaper conductors to get from high voltage transmission, lower voltage distribution and, finally lower voltage consumers. Without this, you need massive conductors and/or high voltages and all the costs that go with them.

AC is less effective, for instance, when transmitting high power over long, uninterrupted distances or feeding high density DC loads. Here, the reactive[1] power penalty of AC begins to dominate. This is a far less common problem, and so "Tesla won" is the widely held mental shortcut. Physics doesn't care, however; the DC case remains and is applied when necessary to reduce cost.

[1] https://en.wikipedia.org/wiki/Electrical_reactance

Re: Data centers are transitioning from AC to DC

#106

Post by ianburrell »

manwe150 wrote: post #93
jacquesm wrote: post #53

Earlier quoted context omitted.

Not going to happen. For the same reason that the US never converted to a higher domestic voltage even though there are many practical advantages. The transition from one system to another at the consumer level would be terrible, even if there would be some advantage (and I'm not sure the one you list is even valid, you'd get DC-DC converters instead because your consumers typically use a lower voltage than the house…

I suppose that still begs the question somewhat, since the US does have 240V (2 phase) already driving many appliances. Why hasn’t it ever become standard for luxury kitchens to have a European-style outlet for use with a European kettle? I know the US already has a different 240V plug shape, so it might have to be an unlicensed installation, but surely someone wanted hot tea faster and did that calculus before?

You can run 240V circuit to kitchen for kettle and put in NEMA 6 outlet. But few people care about fast boil and importing European kettle. Most people use the microwave or stovetop, and 120V kettles are fine in most cases. It will never become a standard thing.

Re: Data centers are transitioning from AC to DC

#107

Post by userbinator »

adrr wrote: post #80
adiabatichottub wrote: post #66

Earlier quoted context omitted.

Your modern fridge is probably going to have an inverter-driven motor, so you're right back to using DC.

All modern appliances and HVACs are using inverter drive motors for efficiency. Brushless DC motors are more efficient though.

"Brushless DC motors" are actually just AC synchronous motors.

Re: Data centers are transitioning from AC to DC

#108

Post by tbrownaw »

manwe150 wrote: post #93
jacquesm wrote: post #53

Earlier quoted context omitted.

Not going to happen. For the same reason that the US never converted to a higher domestic voltage even though there are many practical advantages. The transition from one system to another at the consumer level would be terrible, even if there would be some advantage (and I'm not sure the one you list is even valid, you'd get DC-DC converters instead because your consumers typically use a lower voltage than the house…

I suppose that still begs the question somewhat, since the US does have 240V (2 phase) already driving many appliances. Why hasn’t it ever become standard for luxury kitchens to have a European-style outlet for use with a European kettle? I know the US already has a different 240V plug shape, so it might have to be an unlicensed installation, but surely someone wanted hot tea faster and did that calculus before?

> I know the US already has a different 240V plug shape, so it might have to be an unlicensed installation, but surely someone wanted hot tea faster and did that calculus before?

How expensive would a proper AC->DC->AC brick for that power level be?

Re: Data centers are transitioning from AC to DC

#109

Post by neoCrimeLabs »

The datacenter I built in 2007 was DC.

Many datacenters I'd been to at that point were already DC.

Didn't think this was that new of a trend in 2026, but also acknowledge I did not visit more than a handful of datacenters since 2007.

It just seemed like a undenyably logical thing to do.

Re: Data centers are transitioning from AC to DC

#110

Post by jcalvinowens »

manwe150 wrote: post #93
jacquesm wrote: post #53

Earlier quoted context omitted.

Not going to happen. For the same reason that the US never converted to a higher domestic voltage even though there are many practical advantages. The transition from one system to another at the consumer level would be terrible, even if there would be some advantage (and I'm not sure the one you list is even valid, you'd get DC-DC converters instead because your consumers typically use a lower voltage than the house…

I suppose that still begs the question somewhat, since the US does have 240V (2 phase) already driving many appliances. Why hasn’t it ever become standard for luxury kitchens to have a European-style outlet for use with a European kettle? I know the US already has a different 240V plug shape, so it might have to be an unlicensed installation, but surely someone wanted hot tea faster and did that calculus before?

I wired a UK kettle to an unused 240V range outlet in the US once. It was amazing, boiled a liter of water in just under a minute. Obviously kinda sketchy.
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