8 Nov
2016
8 Nov
'16
9:33 a.m.
On Nov 8, 2016, at 9:22 AM, Paul Koning <paulkoning
at comcast.net> wrote:
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.
TTFN - Guy
On Nov 8, 2016, at 12:08 PM, Guy Sotomayor Jr
<ggs at shiresoft.com> wrote:
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. 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:
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. 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.