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DC Power Saves 15% Energy and Cost @ Data Center
Krishna Dagli writes "Engineers at the Lawrence Berkeley National Laboratory and about 20 technology vendors this month will wrap up a demonstration that they said shows DC power distribution in the data center can save up to 15 percent or more on energy consumption and cost. The proof-of-concept program, set up at Sun Microsystems' Newark, Calif., facility, offered a side-by-side comparison of a traditional AC power system and a 380-volt DC distribution system, running on both Intel-based servers and Sun systems."
Would be interesting to know what the efficiency is of a 380 -> 12/5 DC-DC converter, compared to a traditional 110 AC -> 12/5 DC converter. This is of course only just a part of the total picture, but in the past this has often been mentioned as the reason for _not_ going DC. Maybe with modern switching power supplies, that problem has disappeared.
Browsers shouldn't have a back button!! It's all about going forward...
This issue has a been a hot topic at conferences for data center professionals, with a lot of debate about timetables. Several facility designers are advocating DC distribution as the solution to the current power/cooling challenges. Corporate data center managers like the cost savings projections, but want to see it work in someone else's facility before they put their neck on the line and pitch a DC conversion to their bosses. That's the real value of the Livermore project discussed in TFA - it provides a working model.
Right now the cost of power is remaking the landscape of the data center industry. Yesterday there was another announcement of a huge data center in central Washington State. Sabey will invest $100 million in a facility right up the street from where Microsoft and Yahoo have data centers under construction. It's all about cheap hydro power. Both Microsoft and Yahoo have contracted for more than 40 megawatts of power from the local utility. That's why DC is one of the solutions that will begin to get serious consideration.
RichM
Data Center Knowledge
Yeh some where (I may have lent them out) i have a pair of 1948 GPO handbooks for technicians. Which describes the technology?
Including how to build your lead acid batteries on site (48 hours on battery power was required) and the technical details for the pneumatic tubes used in manual exchanges to send tickets up to the trunk floor
I have also hear some old timers war stores one i liked was about the guy who when painting in an exchange put a paint can on top of the main bussbars - which then shorted - an explosive way of painting a room.
I once had to help install some sun servers in an exchange (CAPITAL) and walking around - the building most of the old stuff had been taken out - was quite eerie lots of clicking and odd buzzes.
CAPITAL is/was one of the main exchanges in the uk its actually in Edinburgh not London Rgds M
You will never get to heaven with an Ak 47... But A Zu 30 is good for Low Flying Cherubim
You have your facts backwards. Human beings are far more sucpetible to Alternating current than to Direct Current. One of the reasons Edison prefereed using Direct Current was that if everything else is the same, house hold Alternating Current will kill you, while the same amount of electricity transformed to Direct Current will not.
excitingthingstodo.blogspot.com
I wonder if you would see the same 15% power saving if a home was outfitted for DC use ? When you think about it most electronic devices in the home have power supplies embedded which are nothing more than AC-DC coverters, which in and of themselves waste energy.
A DC power home would lend itself more readily to home based power generation. I believe most solar panels and windmill generate DC power which then has to be converted back to AC before it can be put on a powerline or used with conventional home appliances. With the new high efficiecy LED DC lights available the AC light bulb (a hundred year old device) is a real power hog and also generates enomrmous amounts of heat.
100 yrs ago when they were first bring electrical power to the masses perhaps AC was the right answer, but I believe our needs and priorities have changed in the past 100 yrs and perhaps the way we generate, distribute and use electricity is due for a new analysis.
1. DC/DC conversion is cheaper and simpler bacause with a 60Hz AC signal, you have *no* power during the zero crossing. The PS has to store the energy in a capacitor or a coil to deliver during the 120 "outages" a second. A DC/DC converter operates at hundreds of kHz, so components are much smaller, and since the conversion uses square waves, it does not have the "outages" a sine function has on the input.
2. A lot of AC/DC switching power supplies is a constant power load on the grid. It tends to draw more Amps as the Voltage decreases, producing a lot of harmonics in the mains power line, and a worse power factor than regular "resistive" equipment. Therefore the mains must be overdesigned to support this kind of load.
2. 220V AC means 220V *RMS*; 110V is just one of the wires tied to ground. The peak-peak is around 311V. Not that different from 380V
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This reminds me of one of the troubleshooting steps taught to me by my old motorcycle gang bros...when you're troubleshooting an engine fails to start problem, first step is decide if it is a fuel delivery or no-spark problem. If you're sure it's a no-spark problem, then firmly grasp the metal part of the spark plug lead and kick the engine over...what's that, you're not willing to do that? Then, you aren't really sure it's a no-spark problem - keep thinking and testing until you are.
There is no God, and Dirac is his prophet.
That's true for transmission over longer distances, but what about those short distances in the data room? Or for that matter, in my home office?
Almost every device I own uses 4.7V or 12V. I look around at work here, and I can see power strips full of transformers, all of which are knocking back the AC power to one of a couple of DC voltage levels. Every one of those transformers has its own losses, most of which dissipates as heat. They're also large, making it difficult to fit them all into a strip, and their heavy, making it difficult to balance or hang the strip where it's most needed. At home I have DC transformers for the monitor, the switch, the firewall/router, the WiFi, the PDA recharger, the BT mouse recharging dock, the USB hub, the TV tuner box, etc, etc. It's got to be a safety hazard.
Then we have the PCs, which are also using 2 (OK, 4) predefined levels of DC voltage, and have their own transformers and rectifiers to do it. These get so hot they even need their own fans!
Why isn't this stuff standardized, and power strips can instead contain one single transformer/recitifer package, with DC sockets, or retractable DC wires coming out of them? Even if we ignored PCs and only did the external peripherals for now, we'd still get a big saving in power just by having fewer transformers.