Supercomputers, fishing for information

[Dave Wade]

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
> Koning
> Sent: 08 November 2016 17:22
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Re: Supercomputers, fishing for information
> 
> 
> > On Nov 8, 2016, at 12:08 PM, Guy Sotomayor Jr <ggs at shiresoft.com>
> wrote:
> >
> >
> >> On Nov 8, 2016, at 8:47 AM, Jon Elson <elson at 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
>