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
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 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 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
> 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
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 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
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
> 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
> On Feb 18, 2018, at 11:02 PM, Chuck Guzis via cctalk
> wrote:
>
> On 02/18/2018 04:55 PM, Al Kossow via cctalk wrote:
>>
>>
>> On 2/18/18 4:07 PM, Chuck Guzis via cctalk wrote:
>>
>>> Generally, the electromechanical stuff (motors) was run from 208V
>>> 3-phase and often, the electronics
On 02/18/2018 04:55 PM, Al Kossow via cctalk wrote:
>
>
> On 2/18/18 4:07 PM, Chuck Guzis via cctalk wrote:
>
>> Generally, the electromechanical stuff (motors) was run from 208V
>> 3-phase and often, the electronics from 400Hz.
>>
>> At least that's what I recall.
>>
>> --Chuck
>>
>
> that isn
On 2/18/18 4:07 PM, Chuck Guzis via cctalk wrote:
> Generally, the electromechanical stuff (motors) was run from 208V
> 3-phase and often, the electronics from 400Hz.
>
> At least that's what I recall.
>
> --Chuck
>
that isn't what the schematic looks like.
there is a low voltage transformer
On 02/18/2018 03:14 PM, Al Kossow via cctalk wrote:
>
>
> On 2/18/18 9:34 AM, P Gebhardt via cctalk wrote:
>
>> As far as I know, some computer installations used 400Hz 3-phase
>> back in the days. Does anybody know, if that is the case for this
>> type of drive systems?
>
> Looking at the manu
On 2/18/18 9:34 AM, P Gebhardt via cctalk wrote:
> As far as I know, some computer installations used 400Hz 3-phase back in the
> days. Does anybody know, if that is the case for this type of drive systems?
Looking at the manuals, it is 3-phase 50Hz, with the phases split between
different pa
I've also uploaded manuals for the BM1A5 and 9461, which may also be of help.
The BM1A5 looks similar to the BM101, and I had all three manuals for it
scanned.
The 841 looks very similar to the IBM 2314, down to putting multiple Drives in
a rack you had to slide out to swap packs.
On 2/18/18 12
On 2/18/18 11:24 AM, Al Kossow via cctalk wrote:
> I've got 41249000
>
> ./___UNSORTED/41249000J_BM101_Theory_jun72.tar
>
>
http://bitsavers.org/pdf/cdc/discs/BM101/41249000J_BM101_Multiple_Disk_Drive_Theory_Jun72.pdf
On 2/18/18 9:34 AM, P Gebhardt via cctalk wrote:
> Hello list,
>
> currently, I am in the process of trying to bring back to life a disk drive
> installation from Control Data known as "841 Multiple Disk Drive" ( MDD ).
"BM101" shown in the pictures is what you should be looking for
90310500_
On 02/18/2018 11:34 AM, P Gebhardt via cctalk wrote:
Hello list,
currently, I am in the process of trying to bring back to life a disk drive installation
from Control Data known as "841 Multiple Disk Drive" ( MDD ). From the early
'70s. It uses hydraulic disk head actuators! Pictures of the su
>The claim about the "only CDC disk drive with hydraulic positioner" is
>false. Starting with the Bryant 6603, I believe that the 808 and very
>rare 821 also used hydraulics. Voice-coil positioners started to be
>used with the 844 drives. I don't recall what the 854 used, as it
>wasn't very com
On 02/18/2018 09:34 AM, P Gebhardt via cctalk wrote:
> Hello list,
>
> currently, I am in the process of trying to bring back to life a disk drive
> installation from Control Data known as "841 Multiple Disk Drive" ( MDD ).
> From the early '70s. It uses hydraulic disk head actuators! Pictures o
> On Feb 18, 2018, at 12:34 PM, P Gebhardt via cctalk
> wrote:
>
> Hello list,
>
> currently, I am in the process of trying to bring back to life a disk drive
> installation from Control Data known as "841 Multiple Disk Drive" ( MDD ).
> From the early '70s. It uses hydraulic disk head actu
Hello list,
currently, I am in the process of trying to bring back to life a disk drive
installation from Control Data known as "841 Multiple Disk Drive" ( MDD ). From
the early '70s. It uses hydraulic disk head actuators! Pictures of the
subsystem are here:
http://www.digitalheritage.de/perip
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