On Tue, Jan 4, 2022 at 8:36 PM Grant Taylor via cctalk <
cctalk@classiccmp.org> wrote:
> My limited understanding is that VFDs simulate / emulate various
> frequencies by turning the output on and off (at full input voltage)
> such that the (sliding) /average/ of the output looks like it's a at a
I mean if you want to add a transformer to it you can do anything to want
with voltages. It doesn't provide you 120V from the service transformer.
Corner grounded Delta gives you a grounded 3 phase service (safer than
ungrounded) with one less wire than high-leg delta (3 instead of 4), making
it c
> Why couldn't 120V be derived from either of the 240V phase and the
> grounded corner via a 2:1 transformer?
It can. That's often how, say, an Edison base decorative luminary is run when
all other lighting is 277V (the ratios would of course be different). Otherwise
someone invariably screws a
On 1/4/22 11:04 AM, Paul Koning via cctalk wrote:
I've said that too, and I've been told that this is not a good idea
for power supplies. Something about the waveforms involved in VFDs.
My limited understanding is that VFDs simulate / emulate various
frequencies by turning the output on and o
On 1/4/22 7:43 PM, Patrick Finnegan via cctalk wrote:
It's the even more obscure corner-grounded delta, which requires even
more care and can't provide 120V power, since the phase to ground
voltage is 240V.
Why couldn't 120V be derived from either of the 240V phase and the
grounded corner via
> For what it's worth, the building I bought has two services installed when
> it was built in 1921 - single phase 120/240 for lighting loads, and 240V
> Delta for three phase loads.
I bet you have a fun electrical system :D
> It's the even more obscure corner-grounded delta
I love the reaction
On Tue, Jan 4, 2022, 18:15 Jonathan Chapman via cctalk <
cctalk@classiccmp.org> wrote:
>
> High-leg delta exists so you can have 120/240 lighting and appliance loads
> in a building that consumes mostly 3-phase, like a machine shop with an
> office. In most areas you aren't allowed to have more th
On Tue, Jan 4, 2022 at 5:17 PM Rich Alderson via cctalk <
cctalk@classiccmp.org> wrote:
>
> We did not have a 3phase outlet on the second floor of the building where
> the
> collection was housed, and there was no room for the first VAX in the small
> computer room on the third floor, so Ian and K
> On Jan 4, 2022, at 7:08 PM, Jonathan Chapman via cctalk
> wrote:
>
>> much of it related to Niagara Falls and other power systems
>> modeled after it.
>
> The IIRC oldest US generating station still in operation (on original
> hardware anyway) is at Mechanicville, NY. It is hydroelectric
On 1/4/22 4:04 PM, Grant Taylor via cctalk wrote:
> I knew about 50 and 60 Hz and DC growing up. I learned about 400 (?) Hz
> being used in military applications about a decade ago. 25 Hz was a
> surprise to me over the last year or so. I read some interesting
> things, much of it related to Ni
> The IIRC oldest US generating station still in operation (on original
> hardware anyway) is at Mechanicville, NY.
Well that ruined my evening, Wikipedia says the generating station now uses the
power to mine bitcoins, because it's more profitable than selling it to the
public grid.
Thanks,
J
> much of it related to Niagara Falls and other power systems
> modeled after it.
The IIRC oldest US generating station still in operation (on original hardware
anyway) is at Mechanicville, NY. It is hydroelectric and originally fed 40 Hz
AC to Schenectady. They just sped up the alternators when
On 1/4/22 4:46 PM, Chuck Guzis via cctalk wrote:
In fact, in my neighborhood, each house has a big green disconnect
box on the street fed by 3-phase 11KV. Every so often, the utility
sends out a notice that they'll be "re-balancing" the distribution.
I imagine that that involves nothing more
On 1/4/2022 5:17 PM, Rich Alderson via cctalk wrote:
I've been reading this thread for the last few days, without the time to reply.
All the statutes of limitations have run out, so I can tell the story; it will
be clear shortly why I'm piggybacking on Guy's post.
Someday we will all gather aro
On Tue, Jan 4, 2022 at 12:00 PM Adrian Stoness via cctalk <
cctalk@classiccmp.org> wrote:
> you can use a vfd drives to get 3phase power from single u just gotta size
> them bigger then the load u would normally need
>
> Yes, in principle this is true. In the simplest case, the VFD input is
just a
On 1/4/22 3:14 PM, Jonathan Chapman wrote:
>> High-leg delta is independent of open- or closed-delta.
>
> That's correct.
>
>> Open delta uses two single-phase transformers primaries connected to
>> phases AB and BC.
>
> A to C is also valid, presumably it's rotated if there's a lot of open delt
> Date: Tue, 04 Jan 2022 14:44:00 -0800
> From: Van Snyder via cctalk
> On Tue, 2022-01-04 at 17:17 -0500, Rich Alderson via cctalk wrote:
>> Paul Allen wanted me to acquire a VAX-11/780 for his
>> collection
> John Zabolitzky has an operating VAX -- I don't know the vintage --
> eleven cabinets
> From: Jon Elson
> It should be 208V
Oh, right you are. It's been a long time, and I had a distinct memory that it
was less than that, but I looked, and I think that's it. The term for my
flavour of 3-phase is apparently "open wye/open delta"; each leg is 240V to
the others, but only two
Dunno if this is useful for anyone but the price seems right:
https://www.ebay.com/itm/Qty-8-Cdc-Dec-Disk-Head-Heads-75010109-75010101-/255306991030
As the owner of a VAX-11/780 I can confirm what Guy says about the 866
power controller. This is the only component that needs 3-phase power.
There is a small 3-phase transformer inside that provides 24V DC to the
control circuitry. The power controller not only interfaces to the DEC
power control
> High-leg delta is independent of open- or closed-delta.
That's correct.
> Open delta uses two single-phase transformers primaries connected to
> phases AB and BC.
A to C is also valid, presumably it's rotated if there's a lot of open delta in
an area (again, why?) to balance phases.
> On hig
On Tue, 2022-01-04 at 17:17 -0500, Rich Alderson via cctalk wrote:
> Paul Allen wanted me to acquire a VAX-11/780 for his
> collection
John Zabolitzky has an operating VAX -- I don't know the vintage --
eleven cabinets, in his collection in Neubiberg, a southeastern suburb
of Munich.
He also has
> Date: Sat, 1 Jan 2022 13:19:51 -0800
> From: Guy Sotomayor via cctalk
> On 1/1/22 10:40 AM, Paul Koning via cctalk wrote:
>>> On Jan 1, 2022, at 1:12 PM, Noel Chiappa via cctalk
>>> wrote:
>>> This:
>>> https://www.ebay.com/itm/275084268137
>>> The starting price is expensive, but pro
>
>
> Date: Mon, 3 Jan 2022 11:39:01 -0500
> From: Chris Zach
>
> The thing that always made me wonder is where are all the 8600's. The
> 8600 was apparently the best selling large Vax, outselling the 780 and
> 750, so what happened to all of them? They weren't any bigger than a 780...
>
> C
>
Th
On 1/4/22 12:15 PM, Jonathan Chapman via cctalk wrote:
> One of the top Google results:
>
> https://www.engineeringradio.us/blog/2012/02/the-open-delta-three-phase-service/
>
> Really really, there's only two pigs on the pole. And yet, delta power,
> though at a lower rating than transformer nam
One of the top Google results:
https://www.engineeringradio.us/blog/2012/02/the-open-delta-three-phase-service/
Really really, there's only two pigs on the pole. And yet, delta power, though
at a lower rating than transformer nameplate (vs. if you had three).
Thanks,
Jonathan
‐‐‐ Original
On 1/4/22 8:52 AM, Jonathan Chapman via cctalk wrote:
Indeed. This is not corner-grounded delta. Once you figure out open
delta, look at dog-leg.
I did some brief reading on open delta and now think that it requires
three lines, independent of ground. So I fail to see how open delta
would be
On 1/4/22 10:04 AM, Paul Koning via cctalk wrote:
> The other option, typically somewhat more expensive but cheaper than an
> 11/780, is a rotary converter. Those are 3 phase motors, sometimes modified
> a bit, driven from single phase power that construct the missing phase
> somewhat like a d
On 1/4/22 7:40 AM, Grant Taylor via cctalk wrote:
> I guess I thought that since Seymour left CDC to form Cray Research,
> that meant that he was more of an employee at CDC and had less influence
> on how it operated as a company. I would have assumed that someone that
> was a founder would have
> On Jan 4, 2022, at 12:00 PM, Adrian Stoness via cctalk
> wrote:
>
> you can use a vfd drives to get 3phase power from single u just gotta size
> them bigger then the load u would normally need
I've said that too, and I've been told that this is not a good idea for power
supplies. Somethi
On Jan 4, 2022, at 4:05 AM, P Gebhardt via cctalk wrote:
>
>
>> There's a photo on twitter:
>>
>> https://twitter.com/DonaldM38768041/status/1215804561333473280/photo/2
>>
>> showing a guy standing before an open one at Fermilab.
>
>
> In of the pictures are shown some very handy tape and di
you can use a vfd drives to get 3phase power from single u just gotta size
them bigger then the load u would normally need
On Tue, Jan 4, 2022 at 10:52 AM Jon Elson via cctalk
wrote:
> On 1/4/22 10:03 AM, Noel Chiappa via cctalk wrote:
> > > From: Scott Quinn
> >
> > > I have seen some
On 1/4/22 10:03 AM, Noel Chiappa via cctalk wrote:
> From: Scott Quinn
> I have seen some roads where the utility has 2 of the phases plus
> neutral going down them, not true 2-phase power, but 2 phases 120/240
> degrees apart with the third phase just not present.
My hous
On 1/4/22 9:40 AM, Grant Taylor via cctalk wrote:
On 1/4/22 12:14 AM, Chuck Guzis via cctalk wrote:
Seymour Cray, along with Bill Norris and Jim Thornton and
others left Remington Rand/UNIVAC after Rand bought the
near-bankrupt ERA. Apparently, the work environment at
Rand was felt to be stifl
> On Jan 4, 2022, at 10:40 AM, Grant Taylor via cctalk
> wrote:
>
> On 1/4/22 12:14 AM, Chuck Guzis via cctalk wrote:
>> Seymour Cray, along with Bill Norris and Jim Thornton and others left
>> Remington Rand/UNIVAC after Rand bought the near-bankrupt ERA. Apparently,
>> the work environmen
Hello,
Has anybody a STC 2925 9-trk Tape Drive.
I need a BIN- or HEX-File from an EPROM on the CP--Card.
It's the PROM #1 with the number 403936303.
Best regards
Lothar
> From: Scott Quinn
> I have seen some roads where the utility has 2 of the phases plus
> neutral going down them, not true 2-phase power, but 2 phases 120/240
> degrees apart with the third phase just not present.
My street has that. The subdivision as a whole has all 3 phases (d
> I apparently need to do more reading.
Indeed. This is not corner-grounded delta. Once you figure out open delta, look
at dog-leg.
Thanks,
Jonathan
On 1/4/22 8:06 AM, Jonathan Chapman via cctalk wrote:
Yes, that's open delta. There are one or two small commercial buildings
here in town that still have open high leg delta service -- that's
240V delta, and one of the 240V transformers is center-tapped to give
120/240 split phase for small lo
On 1/4/22 12:14 AM, Chuck Guzis via cctalk wrote:
Seymour Cray, along with Bill Norris and Jim Thornton and others
left Remington Rand/UNIVAC after Rand bought the near-bankrupt ERA.
Apparently, the work environment at Rand was felt to be stifling.
Norris had all of the Navy connections and was
> I have seen some roads where the utility has 2 of the phases plus
> neutral going down them, not true 2-phase power, but 2 phases 120/240
> degrees apart with the third phase just not present.
Yes, that's open delta. There are one or two small commercial buildings here in
town that still have o
I just added a patch to https://github.com/pkoning2/decstuff, in
patches/shut.cmd, which cures a problem in RSTS V10.1 that seems to come and go
with no clear pattern. The failure is a crash, sometimes a halt, during system
shutdown. The cause was a write to the wrong location when removing th
On Sun, 2022-01-02 at 12:00 -0600, Grant wrote:
> Where are you getting two /different/ phases? -- Remember, the
> different legs on residential 120/240 wiring are really the same
> single
> phase.
>
> How do you get *two* /different/ phases without access to a *third*
> phase? There are onl
>There's a photo on twitter:
>
>https://twitter.com/DonaldM38768041/status/1215804561333473280/photo/2
>
>showing a guy standing before an open one at Fermilab.
In of the pictures are shown some very handy tape and disk pack holders on
wheels. I never saw such fancy holders. Would be great to
Fred, a completely unrelated piece of information, but interesting
nonetheless:
Elnec device programmers are very famous for the number of devices it
programs and its robustness. Also for their clones. If you open a cloned
beeprog you cannot differ it from an original beeprog.
I still haven't com
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