Data centers are transitioning from AC to DC • Hacker News Board

Re: Data centers are transitioning from AC to DC

#171

Post by elar_verole » Wed, Mar 25, 2026, 10:02 AM UTC

chrneu wrote: post #104

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, a…

People need heroes. It's like the Keanu Reeves or Musk era, all the ""badass"" stories about this or that soldier / local hero / w/e that are very often overblown and get further and further away from the initial facts every time they resurface. No hate here, just noticing there is a weird visceral need to distill stories to their most essential, good vs evil, and the Tesla v Edison thing embodies this perfectly I think.

Re: Data centers are transitioning from AC to DC

#172

Post by mr_toad » Wed, Mar 25, 2026, 10:09 AM UTC

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…

> If there was anything like a high power transistor back then he would have used that.

Mercury arc rectifiers were used long before his death.

Re: Data centers are transitioning from AC to DC

#173

Post by jojobas » Wed, Mar 25, 2026, 10:14 AM UTC

HWR_14 wrote: post #154

mjuarez wrote: post #35

Earlier quoted context omitted.

Not to be _that_ guy, but it was technically -48V DC. Honestly, that was pretty surprising to me when I had to work with some telco equipment a couple of decades ago. To this day, I don't think I've encountered anything else that requires negative voltage relative to ground.

Can you explain why it's -48 VDC as opposed to 48 VDC with the + and - inputs mislabeled?

In short, ground.

Re: Data centers are transitioning from AC to DC

#174

Post by da02 » Wed, Mar 25, 2026, 10:24 AM UTC

teleforce wrote: post #121

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…

>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. This! The soon people realized these facts the better. The pervasive high rise buildings did not happen before the invention of modern cranes. Exactly twenty years ago I was doing a novel res…

What are some novel processes or technologies you see becoming more important in the next 5-10 years?

Re: Data centers are transitioning from AC to DC

#175

Post by fecal_henge » Wed, Mar 25, 2026, 10:25 AM UTC

mjuarez wrote: post #35

bluGill wrote: post #16

Earlier quoted context omitted.

48vdc was common in phone exchanges. They filled the basement with lead-acid batteries and to could run without the grid for a couple weeks. In turn the phone was 99.999% reliable for decades.

Not to be _that_ guy, but it was technically -48V DC. Honestly, that was pretty surprising to me when I had to work with some telco equipment a couple of decades ago. To this day, I don't think I've encountered anything else that requires negative voltage relative to ground.

I am STILL designing hardware for -48v telco standard. The first thing we do is convert -48 -> 48v. That's 4 square inches of PCB space we waste.

Re: Data centers are transitioning from AC to DC

#176

Post by eqvinox » Wed, Mar 25, 2026, 10:27 AM UTC

fecal_henge wrote: post #175

mjuarez wrote: post #35

Earlier quoted context omitted.

Not to be _that_ guy, but it was technically -48V DC. Honestly, that was pretty surprising to me when I had to work with some telco equipment a couple of decades ago. To this day, I don't think I've encountered anything else that requires negative voltage relative to ground.

I am STILL designing hardware for -48v telco standard. The first thing we do is convert -48 -> 48v. That's 4 square inches of PCB space we waste.

What do you need +48V for?

Re: Data centers are transitioning from AC to DC

#177

Post by hrmtst93837 » Wed, Mar 25, 2026, 10:35 AM UTC

shdudns wrote: post #3

How is DC better than a three phase delta 800Vrms, at 400Hz? - Three conductors vs two, but they can be the next gauge up since the current flows on three conductors - no significant skin effect at 400Hz -> use speaker wire, lol. - large voltage/current DC brakers are.. gnarly, and expensive. DC does not like to stop flowing - The 400Hz distribution industry is massive; the entire aerospace industry runs on it. No ne…

[flagged]

Re: Data centers are transitioning from AC to DC

#178

Post by mikkupikku » Wed, Mar 25, 2026, 10:37 AM UTC

AndrewDucker wrote: post #170

ta9000 wrote: post #160

Earlier quoted context omitted.

Does that mean when we run out of Ga there are no more LED TVs?

Why would we run out of Ga?

There's a component of modern culture that trains and expects people to be extremely pessimistic about long term human development. It results in situations above, where without any further information people just assume by default that were going to run out of a thing and are on some collision course with not just a disaster, but every single conceivable one.

(Gallium is a byproduct of aluminum production. We aren't going to run out.)

Re: Data centers are transitioning from AC to DC

#179

Post by chipster_f00 » Wed, Mar 25, 2026, 10:39 AM UTC

fsh wrote: post #155

anonymousiam wrote: post #123

Earlier quoted context omitted.

Tesla was an outstanding technologist, but a poor businessman. He had a "vision" (actually more than one) about how his ideas could transform the world. Some of his ideas were amazing, but he was swindled out of his patents because the investors knew he had a passion and wanted to see them in use. The polyphase AC motor or fluorescent light bulb could have made him millions. IMHO, the vision he had about universal fr…

Essentially none of this is true. The war of the currents was between Edison and Westinghouse, not Tesla. Tesla's downfall was that he turned into a crackpot who rejected modern science, such as Maxwell's equations, and started defrauding investors. Edison was an outspoken opponent of the death penalty, and the electric chair used AC simply because it is much more deadly.

> The war of the currents was between Edison and Westinghouse [...]

Thank you for quashing the gross misinformation. I was going to post this, but searched and found your comment. `\m/`

(I learned of the "Current War" in the 70's, since the Edison Museum was in my "backyard" -- and was a common destination of local school field trips.)

Re: Data centers are transitioning from AC to DC

#180

Post by bregma » Wed, Mar 25, 2026, 10:40 AM UTC

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?

> but surely someone wanted hot tea faster

No one in the USA drinks hat tea. The choices (and it tends to be regionally-based) is sweet or unsweet tea. No need to boil a kettle quickly for that.