31 Jan
2002
31 Jan
'02
11:39 a.m.
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
31 Jan
31 Jan
10:11 p.m.
Gunther,
be careful with the return line: if you are running three different
phases, these are phase-shifted 120 degree against each other, so the
current maximum on each phase will occur at a different time, and the
center ("ground") line will not need to carry any current at all (in a
perfectly balanced circuit). If balance is not perfect, the ground wire
will have to bear at most the same load as any of the live wires.
If you feed a single phase into the same circuit on all three lines, you
will have peak current on all three "live" lines at the same time, and
the "ground" line will need to handle that. If it's not made to that
spec, you'll overload it by a factor of 3...
I don't think this is true for VAX power supplies, but I have heard
about process automation computers that are fed with three phases just
to make the period shorter and to use smaller capacitors. With this kind
of power supply, you'd get a lot of ripple on the DC output.
Regards,
Andreas
Gunther Schadow wrote:
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
11:28 p.m.
Gunther,
be careful with the return line: if you are running three different
phases, these are phase-shifted 120 degree against each other, so the
current maximum on each phase will occur at a different time, and the
center ("ground") line will not need to carry any current at all (in a
perfectly balanced circuit). If balance is not perfect, the ground wire
will have to bear at most the same load as any of the live wires.
Not quite correct-- the ground wire will only carry current during a fault
(aside from leakage), and the neutral will (try!) to carry the whole load,
until it burns thru the insulation and shorts out to ground-- then the
ground will start carrying part of the load!
If you feed a single phase into the same circuit on all three lines,
you will have peak current on all three "live" lines at the same time,
and the "ground" line will need to handle that. If it's not made to
that spec, you'll overload it by a factor of 3...
Yes.
I don't think this is true for VAX power supplies, but I have heard
about process automation computers that are fed with three phases just
to make the period shorter and to use smaller capacitors. With this
kind of power supply, you'd get a lot of ripple on the DC output.
The VAX 6K works just fine on 240v single-phase (dryer-like), but I can't
speak for long-term reliability yet. Maybe in another decade or so. ^_^
I dunno how the 780's power supply is constructed, but it _is_ DEC, after
all...
ISTR there was a model that had 3-phase blower motors. A three-phase motor
will not operate on single-phase. It *has* to have all three legs to run.
Check the wires going into it. If there are four, or three and one isn't
green and obviously bonded to the grounding system somewhere, take a good,
hard look at things.
Regards,
Andreas
Bob
Gunther Schadow wrote:
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D.
gschadow(a)regenstrief.org Medical Information Scientist
Regenstrief Institute for Health Care Adjunct Assistant Professor
Indiana University School of Medicine tel:1(317)630-7960
http://aurora.regenstrief.org
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com 
1 Feb
1 Feb
2:19 a.m.
--- Robert F Schaefer <rschaefe(a)gcfn.org> wrote:
ISTR there was a model that had 3-phase blower motors.
A three-phase
motor will not operate on single-phase. It *has* to have all three legs
to run.
We had an 8530 that needed 3-phase. I had to install the plug on the
panel for our AC because our machine-panel only had two legs (everything
we had was single-phase 120VAC except the TU78 - 220V). Our AC was
large enough that it had a 3-phase compressor.
-ethan
__________________________________________________
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3:29 a.m.
--- Robert F Schaefer <rschaefe(a)gcfn.org> wrote:
I would love to have a three-phase service. It's just more efficient for
*anything* with a motor in it, and it makes powering high-current devices
much easier. I really can't justify a 480 volt three phase service, but if
I'm ever in a position to get a new service to my house, I'm going to take
a good hard look at it, and damn the cost.
That AC is probably putting out a whole lot of noise-- have any problems
with that 8530?
ISTR there was a model that had 3-phase blower
motors. A three-phase
motor will not operate on single-phase. It *has* to have all three
legs to run.
We had an 8530 that needed 3-phase. I had to install the plug on the
panel for our AC because our machine-panel only had two legs
(everything we had was single-phase 120VAC except the TU78 - 220V).
Our AC was large enough that it had a 3-phase compressor.
-ethan
Bob
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4:17 a.m.
--- Robert F Schaefer <rschaefe(a)gcfn.org> wrote:
That AC is probably putting out a whole lot of noise--
have any problems
with that 8530?
Big "was", not "is". We shut the doors there in the Fall of 1993,
IIRC.
I scooped up what I could, but we left the 8530 (and the TU-78, and
a pair of RK07s, and about 30 CiTOH VT100 clones, etc., etc.) behind.
I did get its Pro380, the 11/730, 11/750, 11/04, 11/24, 11/34s, 11/03,
11/23s, MicroVAXen, the 8300, the TU80, the raised floor (about 110 tiles)
and a bunch of other stuff (test equipment, printers, dozens of DEC
terminals, comms racks...) There just wasn't room for everything.
I don't remember any particular problems with reliability, but OTOH, it
was mostly a driver test bed for our VAXBI product - the NMI was
substantially different from a native VAXBI machine like the 8300...
turns out we were doing the "wrong thing" in the driver when we went
to stop the board (bad advice from a VMS device driver manual). The 8300
didn't care, but anything with an NMI curled up its toes and died hard.
The fix... commenting out one line of the driver. :-)
-ethan
__________________________________________________
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2:07 a.m.
New subject: Anything special about converting VAX 11/780 to single phase?
Andreas,
The power distribution of a VAX 11/780 is much simpler than that. There is
only one three-phase transformer in the entire machine, and it is used to
power the shutdown interlocks.
The three phases are not combined into any "wye" or "delta"
arrangement
using a transformer (other than the interlock). The front side of the power
distribution panel consists of a bunch of standard 120V three-prong
household outlets, and various portions of the VAX are connected to these
outlets.
It's very easy to convert an 11/780 to run from single-phase power, the
problem is the high current draw, which is more than the typical 15A feed
in our houses. I've been running mine for short periods of time, which each
phase plugged into a different branch circuit in my house. This really
makes GFI protected circuits go bonkers (for obvious reasons), but I've
been very careful not to exceed ampacity of any of the branches.
I wouldn't recommend this to everyone, though. I brought home a Fluke 41
Power Harmonics Analyzer and made a simple test harness so I can actually
measure what is going on with my modification to the 11/780. When Gunther
was visiting, we ran it for about twenty minutes, and that was the longest
run of the machine in my house to date. I was also very cautious to make
sure that none of the "phases" were causing any excessive heating in the
wires, however, this is not a good safety test of the modification.
After safety checks using the 41, my next step is to install those small
inline "Power Planners" to the cooling fans. That should cut the power
requirements of the 780 by a few hundred watts. I've tested those Power
Planners, and for typical AC motors that do not run under a heavy load,
they really do work and cut electrical consumption. They do generate
harmonics, but not any worse than your typical PC switching power supply.
My eventual goal is to run the 780 from a 240V source.
Any yes, my wife thinks it nuts.
- Matt
At 01:11 PM 2/1/2002 +0100, you wrote:
Gunther,
be careful with the return line: if you are running three different
phases, these are phase-shifted 120 degree against each other, so the
current maximum on each phase will occur at a different time, and the
center ("ground") line will not need to carry any current at all (in a
perfectly balanced circuit). If balance is not perfect, the ground wire
will have to bear at most the same load as any of the live wires.
If you feed a single phase into the same circuit on all three lines, you
will have peak current on all three "live" lines at the same time, and
the "ground" line will need to handle that. If it's not made to that
spec, you'll overload it by a factor of 3...
I don't think this is true for VAX power supplies, but I have heard
about process automation computers that are fed with three phases just
to make the period shorter and to use smaller capacitors. With this kind
of power supply, you'd get a lot of ripple on the DC output.
Regards,
Andreas
Gunther Schadow wrote:
Matthew Sell
Programmer
On Time Support, Inc.
www.ontimesupport.com
(281) 296-6066
Join the Metrology Software discussion group METLIST!
http://www.ontimesupport.com/cgi-bin/mojo/mojo.cgi
"One World, One Web, One Program" - Microsoft Promotional Ad
"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler
Many thanks for this tagline to a fellow RGVAC'er...
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
3:21 a.m.
New subject: Anything special about converting VAX 11/780 to single
Andreas,
The power distribution of a VAX 11/780 is much simpler than that. There
is only one three-phase transformer in the entire machine, and it is
used to power the shutdown interlocks.
The three phases are not combined into any "wye" or "delta"
arrangement
using a transformer (other than the interlock). The front side of the
power distribution panel consists of a bunch of standard 120V
three-prong household outlets, and various portions of the VAX are
connected to these outlets.
This sounds similar to the VAX 6k power supply. There are three circuits
tapped off of the three-phase power to feed various pieces-parts, and the
configuration of the DC power supply is such that two legs at 240V is a
close match to three legs at 208V
It's very easy to convert an 11/780 to run from single-phase power, the
problem is the high current draw, which is more than the typical 15A
feed in our houses. I've been running mine for short periods of time,
which each phase plugged into a different branch circuit in my house.
This really makes GFI protected circuits go bonkers (for obvious
reasons), but I've been very careful not to exceed ampacity of any of
the branches.
A moderm dryer (30A) or range (50A) actually has all the connections
required: 2 lines, one neutral, and one ground. If the power supply
neutral is replaced with a properly-sized conductor, it shouldn't be any
big deal to change the cord and run it off of a standard dryer/range
recpt. Make sure you have both the neutral and equipment ground
avaliable-- the older style of electric dryer recpt didn't provide a
neutral, and the ground was often used to provide 120v to the timer!
I wouldn't recommend this to everyone, though. I brought home a Fluke
41 Power Harmonics Analyzer and made a simple test harness so I can
actually measure what is going on with my modification to the 11/780.
When Gunther was visiting, we ran it for about twenty minutes, and
that was the longest run of the machine in my house to date. I was
also very cautious to make sure that none of the "phases" were causing
any excessive heating in the wires, however, this is not a good safety
test of the modification.
The longest run on my VAX 6320 & TU81+ was 24+ hours, on 240V 20A single
phase and 120V 30A respectively, with no adverse reactions except to the
electric meter. I feel confident enough that when I start it up For Real,
it'll run unattended 24/7 until such time as I can't afford to pay the
electric bill.
After safety checks using the 41, my next step is to install those
small inline "Power Planners" to the cooling fans. That should cut the
power requirements of the 780 by a few hundred watts. I've tested
those Power Planners, and for typical AC motors that do not run under
a heavy load, they really do work and cut electrical consumption. They
do generate harmonics, but not any worse than your typical PC
switching power supply.
details?
My eventual goal is to run the 780 from a 240V source.
Any yes, my wife thinks it nuts.
^_^ My wife didn't quie realize just how big a 6K machine was...
- Matt
Bob
At 01:11 PM 2/1/2002 +0100, you wrote:
Gunther,
be careful with the return line: if you are running three different
phases, these are phase-shifted 120 degree against each other, so the
current maximum on each phase will occur at a different time, and the
center ("ground") line will not need to carry any current at all (in a
perfectly balanced circuit). If balance is not perfect, the ground wire
will have to bear at most the same load as any of the live wires.
If you feed a single phase into the same circuit on all three lines,
you will have peak current on all three "live" lines at the same time,
and the "ground" line will need to handle that. If it's not made to
that spec, you'll overload it by a factor of 3...
I don't think this is true for VAX power supplies, but I have heard
about process automation computers that are fed with three phases just
to make the period shorter and to use smaller capacitors. With this
kind of power supply, you'd get a lot of ripple on the DC output.
Regards,
Andreas
Gunther Schadow wrote:
Matthew Sell
Programmer
On Time Support, Inc.
www.ontimesupport.com
(281) 296-6066
Join the Metrology Software discussion group METLIST!
http://www.ontimesupport.com/cgi-bin/mojo/mojo.cgi
"One World, One Web, One Program" - Microsoft Promotional Ad
"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler
Many thanks for this tagline to a fellow RGVAC'er...
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D.
gschadow(a)regenstrief.org Medical Information Scientist
Regenstrief Institute for Health Care Adjunct Assistant Professor
Indiana University School of Medicine tel:1(317)630-7960
http://aurora.regenstrief.org
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
31 Jan
31 Jan
10:12 p.m.
----- Original Message -----
From: "Gunther Schadow" <gunther(a)aurora.regenstrief.org>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, January 31, 2002 08:39 PM
Subject: Anything special about converting VAX 11/780 to single phase?
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
Probably not. I don't have a VAX 11/780 handy to check, but that would only
work if the beast was strictly 120 volt with three circuits used internally,
and the feeders up until the circuits were split apart would be overloaded,
carrying three times their designed current.
How many pins are on the plug? Not counting the ground (usually the round
one in the center) there should be three or four. If four, it might be like
the VAX 6k-- with careful examination you may be able to tie two legs
together safely. If there are only three pins, it's strictly three phase--
time to look into a phase converter!
HTH
thanks,
-Gunther
Bob
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
1 Feb
1 Feb
4:10 a.m.
On Fri, 1 Feb 2002, Robert Schaefer wrote:
If there are only three pins, it's strictly three
phase-- time to look
into a phase converter!
(0) Wasn't there a modification a while back that basically replaced the
hadware that converted from the three-phase to the DC used within the
system, this new hardware supplying the DC directly from another source?
(1) Maybe it would be cheaper to have the electric company upgrade the
power feed to the site.
--
Jeffrey S. Sharp
jss(a)subatomix.com
5:12 a.m.
On Fri, 1 Feb 2002, Robert Schaefer wrote:
On the US model, it's an even swap-- three for two. IIRC on the european
model, it required bypassing a transformer.
If there are only three pins, it's strictly
three phase-- time to look
into a phase converter!
(0) Wasn't there a modification a while back that basically replaced
the hadware that converted from the three-phase to the DC used within
the system, this new hardware supplying the DC directly from another
source?
(1) Maybe it would be cheaper to have the electric company upgrade the
power feed to the site.
Doubt it. They would want you to pick up the cost of adding anything
(wire, transformer, etc) required to add the phase. Think 10's of kilo$'s.
--
Jeffrey S. Sharp
jss(a)subatomix.com
Bob
2 Feb
2 Feb
7:18 a.m.
On Fri, 1 Feb 2002, Julius Sridhar wrote:
On Fri, 1 Feb 2002, Robert F Schaefer wrote:
True, but a fair sized three phase motor makes a pretty good imitation.
- don
Doubt it. They would want you to pick up the
cost of adding anything
(wire, transformer, etc) required to add the phase. Think 10's of kilo$'s.
But large, stable phase converters also run into $10K's.
Peace... Sridhar
1 Feb
1 Feb
1:53 a.m.
New subject: Anything special about converting VAX 11/780 to single phase?
Gunther,
That one single phase would surely need a lot of current - if you intend to
run the entire machine from one power feed. As you recall when you were
visiting Houston, I ran mine from three different sources because all three
together were more than 15 amps.
Those 3 blowers alone account for almost a kilowatt by themselves. (At
least on startup).
I have some more testing to do on mine, but I think I can drop it to two
feeds, which would run from a 240V outlet just fine.
- Matt
At 08:39 PM 1/31/2002 -0500, you wrote:
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
Matthew Sell
Programmer
On Time Support, Inc.
www.ontimesupport.com
(281) 296-6066
Join the Metrology Software discussion group METLIST!
http://www.ontimesupport.com/cgi-bin/mojo/mojo.cgi
"One World, One Web, One Program" - Microsoft Promotional Ad
"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler
Many thanks for this tagline to a fellow RGVAC'er...
8:06 a.m.
Gunther Schadow wrote:
Hi,
just to be sure, I would simply put all three phases on the
same single phase. Are there any problems with that? The
VAX 6000 is much pickier, but the VAX 11 and everything
having the simple power distribution box should be fine,
right?
All right. I need to respond to a few assumptions that had
been made and of course ask Matt Sell a question.
Question first: that shutdown interlock transformer you said
is the only thing that really has anything to do with all 3
phases together. Do I have to take any action with this or
will it be fine?
Comments: the VAX 6000 is really VERY different. It has a
power filter box and then a power & logic box and that
produces DC current to be distributed to DC regulators.
A very involved thing, and that's why the conversion isn't
quite so trivial, although the hardest part was to have
the guts (and the reserve of spares) trying it.
The VAX 11, as the PDP8/A, SA600, and many, many other
DEC equipment has just a power distribution box with
soandsomany phases in, some switching gizmo, and then
panels of standard 110 V plugs labeled 'phase 1', 'phase
2', etc. in either switched or unswitched form. That's all.
The only concern I had was about something like this
interlock transformer that Matt was talking about. Will
I get all my panels powered, the unswitched and the switched
ones?
About this ground alias neutral wire overload, I think that's
just scare without real substance behind it. Given that I
have a 25 to 50 A 110 V single phase circuit to devote, my
wiring will simply be like this:
+--- P1
|
---phase-----------+--- P2
|
+--- P3
---neutral---------+--- N
---ground----------+--- GND
since the phase, neutral (and ground, not that it matters)
wires are all same gauge, the 30A that go through the phase
line come right out of the neutral line. If neutral overloads
phase will too. That's what you have circuit breakers and
the right gauged wireing for. I can see no risk. The only
theoretical risk I could possibly see is that the N line
would be underdimensioned internal to the power distribution
box. But hey, it's DEC, had big DEC ever built anything
under-dimensioned :-).
Matt had a different problem, which was he didn't have
a 30 or 50 A line to begin with.
Finally, there is another thought: I might actually want
to use a 220 V 2 phase (4 wires) line that can do 60 A.
It's the same line that goes into my computer room in the
basement that also runs by my computer room in the
garage. I am thinking of just splicing this wire. It's
certainly not NEC professional, but it will work and the
circuit is overall protected 60 A with big enough wires
everywhere and no problem if power fails (only old
computers who suddenly stop working.) Is there any problem
as far as this interlock transformer is concerned that
suggests I not use the 2x110 V (180 degree) line? I
would do something like this:
---phase1----------+--- P1
---phase2----------+--- P2
|
+--- P3
---neutral------------- N
---ground-------------- GND
Now, there may be a risk. Remember, when I did this same
trick on my 6000 the power would shut down after about
5 minutes run time? It might be a preexisting problem
in the PSU, but it might also be that the interlock stuff
was being fried because of the 180 degree phase difference
i.e. U(P1,P2) being 220 V when it wanted a 120 degree
phase difference with a U(Px,Py) = 110 V * 1.5 = 165 V.
Any idea what it would do, Matt?
thanks
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
10:33 a.m.
New subject: Anything special about converting VAX 11/780 to single phase?
Gunther,
All right. I need to respond to a few assumptions that
had
been made and of course ask Matt Sell a question.
At your service... : )
Question first: that shutdown interlock transformer you
said
is the only thing that really has anything to do with all 3
phases together. Do I have to take any action with this or
will it be fine?
Remove the fuses from F2 and F3 on the power distribution panel. Leave F1
fuse in place.
Comments: the VAX 6000 is really VERY different. It has
a
COMPLETELY different.... : )
The only concern I had was about something like this
interlock transformer that Matt was talking about. Will
I get all my panels powered, the unswitched and the switched
ones?
Yes.
About this ground alias neutral wire overload, I think
that's
just scare without real substance behind it. Given that I
have a 25 to 50 A 110 V single phase circuit to devote, my
wiring will simply be like this:
+--- P1
|
---phase-----------+--- P2
|
+--- P3
---neutral---------+--- N
---ground----------+--- GND
If you have that kind of "ampacity", then I don't think you'll need
those
three extension cords and reel that I have to use....
Just wire it all together. I would be careful about the gauge of wire used
for the neutral - one amp on each phase equals three on the neutral. It may
be too much of a load on the neutral wire.
since the phase, neutral (and ground, not that it
matters)
wires are all same gauge, the 30A that go through the phase
line come right out of the neutral line.
On three phase, if you had a 1 amp load on each phase, you would have a
little more than 1 amp through the neutral since they are 120 degrees
apart. With all three phases on one circuit, there is no phase difference
and the neutral bears the same current as all three phases together. It's
been too long since my power distribution classes in college for me to
remember the exact formulas off the top of my head. RF communications and
digital logic were my specialties......
If neutral overloads
phase will too. That's what you have circuit breakers and
the right gauged wireing for.
What size circuit breaker is connected inline with the neutral? That would
determine your total capacity - if connected this way. For example, if you
had a 30 amp breaker on the neutral, then each phase could draw 10 amps
constant.
I can see no risk. The only
theoretical risk I could possibly see is that the N line
would be underdimensioned internal to the power distribution
box. But hey, it's DEC, had big DEC ever built anything
under-dimensioned :-).
The neutrals are separate inside of the distribution box.
Matt had a different problem, which was he didn't
have
a 30 or 50 A line to begin with.
Tell me about it. I'll need an electrician to make a house call when the
6660 arrives.
Finally, there is another thought: I might actually
want
to use a 220 V 2 phase (4 wires) line that can do 60 A.
That was my plan - to move to attempting to "balance" as best as possible
two of the three phases and use 240 V.
It's the same line that goes into my computer room
in the
basement that also runs by my computer room in the
garage.
Your house was made for this......
I am thinking of just splicing this wire. It's
certainly not NEC professional, but it will work and the
circuit is overall protected 60 A with big enough wires
everywhere and no problem if power fails (only old
computers who suddenly stop working.)
Careful where you make these modifications. I don't know what your local
building codes are.....
Is there any problem
as far as this interlock transformer is concerned that
suggests I not use the 2x110 V (180 degree) line? I
would do something like this:
---phase1----------+--- P1
---phase2----------+--- P2
|
+--- P3
---neutral------------- N
---ground-------------- GND
That's what I'm hoping to do for mine.
Now, there may be a risk. Remember, when I did this
same
trick on my 6000 the power would shut down after about
5 minutes run time? It might be a preexisting problem
in the PSU, but it might also be that the interlock stuff
was being fried because of the 180 degree phase difference
i.e. U(P1,P2) being 220 V when it wanted a 120 degree
phase difference with a U(Px,Py) = 110 V * 1.5 = 165 V.
Any idea what it would do, Matt?
I don't think you'll have a problem with the 780. I don't know much about
the 6000's, but the 780 is different as far as the power requirements are.
It seems as if three-phase was used just for the convenience of hooking
this beast up. Once you open that power distribution panel you'll see just
how simple it is. I couldn't believe my luck when I saw the internal wiring.
Hope this helps.....
- Matt
12 May
12 May
3:18 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
Hi Matt and all,
now I'm getting there, my family is gone to Germany again
so I can mess up the house. I am getting ready to hook up
my VAX 11/780, UNIBUS cabinet, TE16 and TU78, move the other
VAX6000 into the basement, run CI cable between the garage
and the basement etc. I need some more ideas about the power
situation.
As I said I have that two-phase 220 V line running through my
garage and down into the basement. I'm going to splice off
a minor branch. This is not going to be NEC proper, but I
need the 60 A rating for the VAXen in both places. May be at
some point I have figured out the exact load balance and then
I'll put in distributor panels with proper circuit breakers
on the branch circuits.
So, the following is what I plan for wiring up the 11/780:
> ---phase1----------+--- P1
>
> ---phase2----------+--- P2
> |
> +--- P3
>
> ---neutral------------- N
>
> ---ground-------------- GND
Matt, you were suggeting to screw off the fuses F2 and F3
in order to protect this shutdown interlock gizmo? What's
the exact situation here? I am kind of lazy about removing
the power distributor box and look for myself, because it's
all so nicely mounted right now. I even have taken the
power outlet box with me when we removed the machine from
it's original site, so, all I'm going to do is wire things
in the power outlet box and then everything else will just
plug in.
While we are at it, is there a good standard way of splicing
a branch from a wire without cutting the wire? This one is a
#6 wire, a real hassle to mess with, and I don't have any
spare length. So, I was hoping to find a T-piece connector
to just interpose:
______________
================ ==================
~~~~+ || +~~~~
| || |
| || |
||
||
||
||
and then tie the wires in the T-piece with a nice and clean
screw each, instead of such messy twist-on caps. Ideally, the
T-piece would be covered in an insulating plastic shell. But
such T-pieces were nowhere to be found at my home-improvement
store. So, I settled with taps, the size of a fat bolt with
a deep notch and a nut with a kind of a wedge. This I can
put over the wire without cutting it and so I can clamp the
lines of the branch in. It's going to be quite some fiddling
but it's the best I could come up with. Any better ideas?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistant Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org
5:45 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
On Sun, 12 May 2002, Gunther Schadow wrote:
Hi Matt and all,
<snip>
So, the following is what I plan for wiring up the 11/780:
You will probably want to wire the 6000 you're gonna power off of the same
branch opposite - connect P1 and P3 to phase 1 and P2 to phase 2, to make
sure you balance everything as much as possible. Personally, I'd
recommend getting rid of the power distribution box and using a couple of
power strips instead - put P1 and half of P2 on one phase, and P3 and the
rest of P2 on the other phase. You'll want to have a current meter of
some sort to help balance things out - get a clamp on one, a cheap one is
worth it.
You can turn on the power strips in the proper order to simulate the old
power distribution box.
> ---phase1----------+--- P1
>
> ---phase2----------+--- P2
> |
> +--- P3
>
> ---neutral------------- N
>
> ---ground-------------- GND
While we are at it, is there a good standard way of
splicing
a branch from a wire without cutting the wire? This one is a
#6 wire, a real hassle to mess with, and I don't have any
spare length. So, I was hoping to find a T-piece connector
to just interpose:
______________
================ ==================
~~~~+ || +~~~~
| || |
| || |
||
||
||
||
NOOOOOOO!!!!! Go spend another $10 and get a few extra feet of wire, a
small propane torch, some solder and a couple wire nuts. Cut and twist
all three wires, solder them together, and put the wire nut on, secure
with electical tape. If you want, you could skip the soldering part. But
dont, DONT use a T-splice on 120V/240V. It's OK on ground wires, but
that's all the stuff is meant for.
All I've gotta say is spend the extra couple dollars to do it right now.
The NEC was written by analyzing electrical fires. You don't really want
to have your home burn to the ground because you were trying to save a few
dollars.
-- PAt
11:23 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
----- Original Message -----
From: "Pat Finnegan" <pat(a)purdueriots.com>
To: <classiccmp(a)classiccmp.org>
Cc: "Matthew Sell" <msell(a)ontimesupport.com>
Sent: Monday, May 13, 2002 01:45 AM
Subject: Re: Anything special about converting VAX 11/780 to single phase?
You will probably want to wire the 6000 you're
gonna power off of the same
branch opposite - connect P1 and P3 to phase 1 and P2 to phase 2, to make
sure you balance everything as much as possible. Personally, I'd
recommend getting rid of the power distribution box and using a couple of
power strips instead - put P1 and half of P2 on one phase, and P3 and the
rest of P2 on the other phase. You'll want to have a current meter of
some sort to help balance things out - get a clamp on one, a cheap one is
worth it.
<nitpick> Two-phase is most highly unlikely to be found in a house-- you
would probably have to generate it yourself. Standard is 120/240 single
phase, refered to as the A leg and B leg around here.</nitpick>
You can turn on the power strips in the proper order to simulate the old
power distribution box.
It sounds like he's refering to split-bolts (a bolt-like thing with a slot
down the middle threaded part and a nut that cranks down and closes the
slot) These are acceptable for taps on non-grounded conductors, but make
sure you insulate them good! Personally I don't think you'd be able to get
them wrapped well enough without pulling them out into a loop, and then you
might as well use wirenuts. You are placing the taps in a junction box,
right?
I don't have my Code book handy, but I wouldn't run anything smaller than a
#6 for 60A-- you might have to go to a #4 for that kind of current.
While we are at it, is there a good standard way
of splicing
a branch from a wire without cutting the wire? This one is a
#6 wire, a real hassle to mess with, and I don't have any
spare length. So, I was hoping to find a T-piece connector
to just interpose:
______________
================ ==================
~~~~+ || +~~~~
| || |
| || |
||
||
||
||
NOOOOOOO!!!!! Go spend another $10 and get a few extra feet of wire, a
small propane torch, some solder and a couple wire nuts. Cut and twist
all three wires, solder them together, and put the wire nut on, secure
with electical tape. If you want, you could skip the soldering part. But
dont, DONT use a T-splice on 120V/240V. It's OK on ground wires, but
that's all the stuff is meant for.
All I've gotta say is spend the extra couple dollars to do it right now.
The NEC was written by analyzing electrical fires. You don't really want
to have your home burn to the ground because you were trying to save a few
dollars.
This is one of those times when a professional really should be consulted.
-- PAt
Bob
13 May
13 May
1:12 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
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2 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
On Tue, 14 May 2002, Tony Duell wrote:
I'd agree. I'm assuming he meant split-blots, which are really meant for
ground wires. The point is that it's much harder to properly insulate a
split bolt than a wire nut.
Which are best used on soldered wires :). At least you should tightly
twist and then tape the wires before putting the nut on. Preferably,
solder them together.
NOOOOOOO!!!!!
Go spend another $10 and get a few extra feet of wire, a
small propane torch, some solder and a couple wire nuts. Cut and twist
all three wires, solder them together, and put the wire nut on, secure
with electical tape. If you want, you could skip the soldering part. But
dont, DONT use a T-splice on 120V/240V. It's OK on ground wires, but
that's all the stuff is meant for.
IMHO the ground wire should be the best connection of the lot, for 2
reasons : Over here, we don't solder mains distribution
wiring (or at least, I
can't think of a time when you do). We get 'junction boxes' -- round
plastic boxes with (normally) 4 screw terminals inside. I've seen them in
up to 30A rating. Those are what is generally used to take a 'spur' off a
power cable.
Typically you don't do that here either, but it does a good job of
guaranteeing that crappy wire-nuts dont fall off and let the wires come
apart.
We don't seem to have the junction boxes with a terminal strip in them
here. The closest thing would be to buy a couple of ground bars (the ones
with screws that you would put in a mains panel) stuck into a garden
variety junction box with appropriate insulating standoffs.
All I've gotta say is spend the extra couple dollars to do it right now.
The NEC was written by analyzing electrical fires. You don't really want
And for some odd reason it still approves of the use of those infernal
'wire nuts'.... -tony
9:04 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
While talking about splicing off a smaller wire from a larger one,
wouldn't the smaller branch require a separate fuse with a lower rating
to protect the thin wire in case of a short? And shouldn't this fuse be
placed where the smaller wire starts, at the place where the splice is?
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
Over here, we
don't solder mains distribution wiring (or at least, I
can't think of a time when you do). We get 'junction boxes' -- round
plastic boxes with (normally) 4 screw terminals inside. I've seen them in
up to 30A rating. Those are what is generally used to take a 'spur' off a
power cable.
Typically you don't do that here either, but it does a good job of
guaranteeing that crappy wire-nuts dont fall off and let the wires come
apart. 
11:03 p.m.
New subject: Anything special about converting VAX 11/780 to single phase?
On Tue, May 14, 2002 at 11:04:53AM +0200, Andreas Freiherr wrote:
While talking about splicing off a smaller wire from a
larger one,
wouldn't the smaller branch require a separate fuse with a lower rating
to protect the thin wire in case of a short?
Sort of. You have to use all the same
wire and the same rated
connectors, or you have to install a sub panel. Im Germany you
need at least 10mm^2 (16mm^2 ?) cable to and a 63A fuse in front
of the sub panel in the main panel.
Or somthing like that. Is to long (12 years?) since I worked
as electrician... and VDE 0100 may have changed in that time too.
In general splicing high current lines is a bad idea. The splice
puts additional resistence in the circuit. When made bad, the splice
will run hot when a lot of power is sucked down the line ... then
you need the fire department. =:-()
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
8257
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22 comments
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participants (11)
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Andreas.Freiherr＠Vishay.com -
ard＠p850ug1.demon.co.uk -
donm＠cts.com -
erd_6502＠yahoo.com -
gunther＠aurora.regenstrief.org -
jkunz＠unixag-kl.fh-kl.de -
jss＠subatomix.com -
msell＠ontimesupport.com -
pat＠purdueriots.com -
rschaefe＠gcfn.org -
vance＠ikickass.org