Re: UPS Recommendations
On 08/27/2010 06:00 AM, Charles Curley wrote: >> http://news.cnet.com/8301-1001_3-10209580-92.html > > Did you notice the publication date on that? Yes, but it still seems like a good idea. Switching power supplies already have most of the circuitry you would need to manage a battery. Shane /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
job of assistant to IT manager
Pluggers: Looking for someone to fulfill the position of assistant to IT manager. Company: Aquaveo Schedule: Part time from 8 AM to 5 PM # of Hours: anywhere from 5 to 20 hours per week. (If you're a student and need to attend school, take a test, etc, no problem.) Work will include: PC support (hardware - building computers from scratch, installing new graphics cards, replacing hard disks, installing drivers, troubleshooting) PC support (software - XP, Vista, Windows 7 - administration, helping users resolve issues such as printing, email, etc) Server support (Windows 2003, 2008, Linux - (Gentoo, CentOS) Networking (firewalls, DNS, DHCP, TCP/IP, wiring, switches, etc) Programming (PHP, CSS, MySQL, Ajax, Javascript, BASH, etc) General IT Admin (SVN, Samba, Apache, Sendmail, Postfix, etc) Organizing (keeping track of IT purchases, track of software, budgets, etc) I don't expect this person to be an expert in anything above, just to have had some good exposure to many items and be willing to learn. In short, I need help. This person will be asked to do everything that I don't have time to do or that I don't have the time to figure out. Here's the chance for a someone (probably most likely a student) to experience what it's really like to do IS/IT first hand. Contact me off the list at move...@aquaveo.com Pay: DOE Merrill Oveson /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
Re: UPS Recommendations
On 08/27/2010 01:56 AM, Shane Hathaway wrote: > So, for a time, the UPS generates power at a slightly incorrect > frequency in order to adjust the phase? That's a cool hack. That's my understanding. The generator is generating a standard 60 Hz sine wave on each of the three phases. The problem is that the generator's phase is never going to be the same as the line's. So the UPS slowly (well, quickly actually) shifts the phase by slightly altering the frequency until it matches the generator's. Then when the line power comes back, it has to shift to match the line's phase. > I prefer the idea of putting batteries in the computer, though. It > works for laptops, why not for servers? Line UPS works for *everything*, which is why it's can be appealing for data centers. Covers the servers, switches, monitors, heating and cooling, lights, etc. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
Re: UPS Recommendations
On Fri, 27 Aug 2010 01:56:57 -0600 Shane Hathaway wrote: > On 08/26/2010 09:40 PM, Michael Torrie wrote: > > Generators bring some interesting things to the mix. As you say you > > can't have a generator without a UPS. But the UPS has to be pretty > > smart when switching back and forth between line, battery, and > > generator. Not only does the UPS have to carry the load while the > > generator gets up to speed, it also has to match phase with the > > generator. This doesn't take very long, but you have to have a > > pretty expensive UPS to do this. Then when line power returns, the > > UPS has to carry the load again while it adjusts the phase to match > > the line phase. We have a nice big, in-line UPS at work that does > > all this. Works well if you have the resources. > > So, for a time, the UPS generates power at a slightly incorrect > frequency in order to adjust the phase? That's a cool hack. Yup. I worked briefly for a company that takes generators, batteries, etc., builds them into its own UPSs, and then sticks them into back alleys for cable companies, those green boxes on concrete pedestals that most people just ignore. The problem is when power returns. The battery system or the generator is cranking out AC power, but it may be out of phase with with the mains. Also, power may not be reliable for some seconds after it returns, so you have to wait for several seconds between the return of stable power and when you finally let that power on to the circuits you are providing power to. So you adjust your phasing from 60 hertz to a bit above or below that, for long enough to get the two in synch. Only then do you let power from the mains go to the load. Another, related, issue is the definition of stable power. Mains power is normally very noisy; that is why we have surge protectors. After a power failure it is extremely noisy. You don't want to allow the load to see that power until it has settled down. Similarly for the period after a power failure, when you shift from battery power to alternator. > > I prefer the idea of putting batteries in the computer, though. It > works for laptops, why not for servers? Laptops are expected to operate on their own, out next to the swimming pool, off the mains, for hours. Servers are not. Different mission. Also, having hundreds or even thousands of batteries in a data center to replace instead of only a few is a maintenance nightmare; no thanks! And add in the recycling issues. Also now you have hundreds or thousands of charging circuits, power conditioners, etc., for the batteries, and that is more expensive that a few large charging circuits, etc. > > http://news.cnet.com/8301-1001_3-10209580-92.html Did you notice the publication date on that? -- Charles Curley /"\ASCII Ribbon Campaign Looking for fine software \ /Respect for open standards and/or writing? X No HTML/RTF in email http://www.charlescurley.com/ \No M$ Word docs in email Key fingerprint = CE5C 6645 A45A 64E4 94C0 809C FFF6 4C48 4ECD DFDB /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
Re: UPS Recommendations
On 08/26/2010 09:40 PM, Michael Torrie wrote: > Generators bring some interesting things to the mix. As you say you > can't have a generator without a UPS. But the UPS has to be pretty > smart when switching back and forth between line, battery, and > generator. Not only does the UPS have to carry the load while the > generator gets up to speed, it also has to match phase with the > generator. This doesn't take very long, but you have to have a pretty > expensive UPS to do this. Then when line power returns, the UPS has to > carry the load again while it adjusts the phase to match the line phase. > We have a nice big, in-line UPS at work that does all this. Works well > if you have the resources. So, for a time, the UPS generates power at a slightly incorrect frequency in order to adjust the phase? That's a cool hack. I prefer the idea of putting batteries in the computer, though. It works for laptops, why not for servers? http://news.cnet.com/8301-1001_3-10209580-92.html Shane /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
