> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul > Koning > Sent: 08 November 2016 17:22 > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk@classiccmp.org> > Subject: Re: Supercomputers, fishing for information > > > > On Nov 8, 2016, at 12:08 PM, Guy Sotomayor Jr <g...@shiresoft.com> > wrote: > > > > > >> On Nov 8, 2016, at 8:47 AM, Jon Elson <el...@pico-systems.com> wrote: > >> > >> On 11/07/2016 10:31 PM, Jon Elson wrote: > >>> On 11/07/2016 07:59 PM, Mark Linimon wrote: > >>>> On Mon, Nov 07, 2016 at 11:23:58AM -0800, Chuck Guzis wrote: > >>>>> But if you're a suburban resident living on Mulberry Street, > >>>>> anything but single-phase is pretty much out of the question. > >>>> Oh, you can get it -- but be prepared for a large hassle. > >>>> > >>>> A former neighbor had a 440V 3-phase Italian lathe in his backyard > >>>> shop, among other toys. After he was laid off from his aerospace > >>>> job doing machining it was how he made his living. He was a very > >>>> handy person to know :-) > >>>> > >>>> mcl > >>>> > >>> I have two 3-phase machines in my shop (Bridgeport mill and Sheldon > lathe) and run them each off a properly-sized VFD. 2-phase in, 3-phase out, > plus variable speed and dynamic braking. > >>> > >>> Jon > >>> > >> And, of course, that is really SINGLE-PHASE power on 2 wires, just to save > anybody the trouble of correcting my error. > >> > > > > I’m looking to have to do something to get 3-phase for the IBM 4331 gear. I > haven’t quite added up the power requirements yet but I’m guessing its > going to be in the 10-15kVA range. Since the power to all of the gear is > really > split between 3 loads (string of 4 3340 drives, 3803 control unit + 2 3420 > tape > drives and 2821 control uint + 1403 printer + 2540 card reader/punch) I need > to figure out if it’s best to have one big converter or 3 smaller ones. It’s > unlikely that I’d be running all of the peripherals at once. The 4331 itself > runs > off of single phase 220v. >
Not sure how familiar with the 4331 you are, but from what I remember, the microcode checks devices at poweron and may get itself in a tizz If peripherals are not powered on... Dave > A VFD is a good option and may be quite economical if you get one of the low > cost simple ones. I have one (3 hp model for my lathe) that cost only a bit > over $100, though the price has gone up since. (Westinghouse TECO brand.) > VFDs specified for single phase input tend to stop around 3 hp, as far as I > have seen. Rumor has it that higher power units will also work (possibly with > some derating) even though they claim to be 3 phase input, when you feed > them just one phase on 2 of the 3 wires. I haven't tried that (but it matches > how my VFD is connected). > > The other option is a "rotary converter". Basically that's a 3 phase motor > connected to one phase power (with a start and run capacitor); it generates > the missing phase roughtly in dynamotor fashion. Those can be built (articles > on the web) or bought from machinery supply companies such as Enco; they > show models up to 20 hp, i.e., about 15 kW. When I was looking into > converters, I found VFDs to be the less expensive option. The instant > reverse and variable frequency features were also attractive for lathe use; > for powering computers that would not apply. Well, not unless you need 400 > Hz for your Cyber 6600 -- in which case you'd need to check the VFD will go > that high, not all do. > > Given that you have a number of smaller devices and that not all might need > to run, several smaller converters sounds like a good option, especially if > that > gets you into the "economy VFD" range. > > paul >