In Edison’s Revenge, Data Centers Are Transitioning From AC to DC

shdudns

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 need for niche or custom parts. - 3 phase @ 400Hz is x6 = 2.4kHz. Six diodes will rectify it with almost no relevant amount of ripple (Vmin is 87% of Vmax) and very small caps will smooth it. As an aside, with three (or more) phase you can use multi-tap transformers and get an arbitrary number of poles. 7 phases at 400Hz -> 5.6kHz. Your PSU is now 14 diodes and a ceramic cap. - you still get to use step up/down transformers, but at 400Hz they're very small. - merging power sources is a lot easier (but for the phase angle) - DC-DC converters are great, but you're not going to beat a transformer in efficiency or reliability

bandrami

I stg if I see the kids talk about Westinghouse being batterymogged I'm leaving the Internet

otterley

DC power has been an option for datacenter equipment since I was a young lad racking and stacking hardware. Cisco, Dell, HPE, IBM, and countless others all had DC supply options. Same with PDUs. What’s old is new again. See e.g. https://www.dell.com/support/kbdoc/en-us/000221234/wiring-in...

stego-tech

I've been hearing this line for over a decade, now. "Immersion cooling will make data centers scale!" "Converting to DC at the perimeter increases density!" Yes, of course both of those things are true, and yes, some data centers do engage in those processes for their unique advantages. The issue is that aside from specialty kit designed for that use (like the AWS Outposts with their DC conversion), the rank-and-file kit is still predominantly AC-driven, and that doesn't seem to be changing just yet. While I'd love to see more DC-flavored kit accessible to the mainstream, it's a chicken-and-egg problem that neither the power vendors (APC, Eaton, etc) or the kit makers (Dell, Cisco, HP, Supermicro, etc) seem to want to take the plunge on first. Until then, this remains a niche-feature for niche-users deal, I wager.

hristov

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 these high voltages. And transformers only work with ac. So he designed an ac system and even designed some better transformers for it. If there was anything like a high power transistor back then he would have used that. High power transistors that are robust enough to handle the grid were designed inly recently over 100 years after the tesla/edison ac/dc argument.

sghiassy

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

umvi

I don't understand why new houses don't just have one high quality AC/DC converter so you can just use LED lighting without every bulb needing its own AC/DC converter. I imagine the light bulb cartel wouldn't really like that.

adrr

Our houses should be DC. So wasteful to have all these bricks to change to AC to DC.

Aloisius

This article seems to imply that 800V DC is high-voltage DC, but that seems quite low.

KnuthIsGod

Waiting for home DC. It is silly to have AC to DC converters in all of my wall connected electronics ( LED bulbs, home controller, computer equipment etc )

skullone

Transitioning? It already happened decades ago. Only smaller scale/generic or less proficient "we bought all Dell and HP" use AC. At large scale it's been a ton of DC for literally decades. And for 70 years in telco and network gear.

b00ty4breakfast

They're still converting from AC to DC at the datacenter, it just isn't being stepped down at the perimeter. There is no transmission of HVDC going on. This isn't really Edison's revenge, more like his consolation price, ha!

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.

Animats

800V to each rackmount unit, with hot plugging of rack units? That's scary. The usual setup at this voltage is that you throw a hulking big switch to cut the power, and that mechanically unlocks the cabinet. But that's not what these people have in mind. They want hot-plugging of individual rackmount units. GE has a paper about the power conversion design, but it doesn't mention the unit to rack electrical and mechanical interface. Liteon is working on that, but the animation is rather vague.[2] They hint at hot plugging but hand-wave how the disconnects work. Delta offers a few more hints.[3] There's a complex hot-plugging control unit to avoid inrush currents on plug-in and arcing on disconnect. This requires active management of the switching silicon carbide MOSFETs. There ought to be a mechanical disconnect behind this, so that when someone pulls out a rackmount unit, a shutter drops behind it to protect people from 800V. All these papers are kind of hand-wavey about how the electrical safety works. Plus, all this is liquid-cooled, and that has to hot-plug, too. [1] https://library.grid.gevernova.com/white-papers-case-studies... [2] https://www.youtube.com/watch?v=CQOreYMhe-M& [3] https://filecenter.deltaww.com/Products/download/2510/202510...

amluto

I wonder how much of the benefit is simpler redundant power equipment. For AC, you have standby UPSes and line-interactive UPSes and frequency and phase synchronization. And everything needs a bit more hold-up time because, in case of failure, your new power supply might be at a zero crossing. For 800V DC, a simple UPS could interface with the main supply using just a pair of (large) diodes, and a more complex and more efficient one could use some fancy solid state switches, but there’s no need for anything as complex as a line-interactive AC UPS.

saltyoldman

The large brick you have on all your tech when you plug it in is the converter. AC works great for some applications, none of them really technical in nature.