On Tue, 8 Nov 2016 09:33:37 -0800 Guy Sotomayor Jr <[email protected]> wrote:
> > On Nov 8, 2016, at 9:22 AM, Paul Koning <[email protected]> > > wrote: > > > > > >> On Nov 8, 2016, at 12:08 PM, Guy Sotomayor Jr <[email protected]> > >> wrote: > >> > >> > >>> On Nov 8, 2016, at 8:47 AM, Jon Elson <[email protected]> > >>> 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. > > > > 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. > > Yea, that’s what I’m struggling with. The issue is that the control > units power the devices that are connected to them (from what I can > tell), so I have to power the entire string as one unit. The same > goes for the 3340’s - the entire string is powered as a unit. The > string of 3340’s need ~5kVA (I don’t know how that translates to > HP). I’m still trying to figure out the requirements for the other > strings. Here's a "conversion" website: http://ncalculators.com/electrical/kva-conversion.htm Cheers, Lyle -- 73 AF6WS Bickley Consulting West Inc. http://bickleywest.com "Black holes are where God is dividing by zero"
