I'm not an engineer, but I question the thought that 3-phase protects against the loss of a single phase. In my experience, the couple of times that we dropped a phase, things either didn't run at all or did very strange things (interesting sounds coming from the a/c unit)..the IBM mainframe equipment didn't power-up at all without all 3 phases. -Bob
-----Original Message----- From: The IBM z/VM Operating System [mailto:[email protected]] On Behalf Of Brian Nielsen Sent: Monday, May 04, 2009 9:23 AM To: [email protected] Subject: Re: z890 power: 3 phase vs 1 phase? On Mon, 4 May 2009 00:20:27 -0500, Alan Ackerman <[email protected]> wrote: >On Fri, 1 May 2009 13:09:38 -0400, Rich Greenberg <[email protected]> wrote: > >>On: Fri, May 01, 2009 at 11:53:04AM -0500,Brian Nielsen Wrote: >> >>} In any case, cost per kwh is not relevant since the site is charging >>a } flat fee for the installed circuit, not for the amount of power >>drawn } through the circuit. >> > >What I remember is that 3-phase current is more efficient for running motors. (I used to know >why, but not any more.) I think that's why my house has 3-phase in the basement to run the >washer and dryer. I never heard any reason why it would be better for running a computer. (Does >a z890 include a motor?) > >But what do I know? I am a programmer, not an engineer. So are most of >us on this list. Ditto for me. I'm not an engineeer, but I play one in this commercial. >I'd suggest you might want to ask your question somewhere that >electrical engineers hang out. >From an electrical standpoint I already understand that 3-phase protects against loss of a single phase and is more effecient for large motors. Given the breadth of experience on this list I was hoping to translate that into real world experience from a z perspective. >But if there isn't any difference in your cost, why do you care? >Unless, as Rich suggested, 3-phase >is more reliable. The monthly flat rate charged by the site housing our DR equipment is higher for 3-phase than for 1-phase, so the bean counters care. My task is to try to understand what we lose/gain with the options from a cost/benefit perspective. So far I see no big benefits to 3-phase for a z box that has dual power feeds at a site with UPS and generators. For the record, we're going with the 1-phase option for the z890. Now to finish navigating through the amperage options for an ESS-800... Brian Nielsen
