8 Nov
2016
8 Nov
'16
11:51 a.m.
-----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
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
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.
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