20 Apr
2001
20 Apr
'01
6:31 a.m.
Sridhar,
here is the URL to this material:
http://www.decvax.org/vax6000/power.txt
I have tried to mail the wizard who writes the in depth stuff, but his
email address is no longer valid. So, what you see is what you get.
I have thought about this again last night and came to a conclusion that
I should just try it out.
DISCLAIMER: I AM NOT COMPLETELY CONFIDENT OF THIS AND I HAVEN'T TRIED
IT OUT YET. SO, READ ALL OF THE BELOW CRITICALLY, DON'T JUST TRUST ME
BUT THINK FOR YOURSELF. PLEASE LET ME KNOW ANY CONCERNS OR DOUBTS YOU
MIGHT HAVE ABOUT THE CORRECTNESS OF WHAT I SAY BELOW.
Let's look at the plan again:
____________________ +300V
| | |
-__ -__ -__ thyristors
^ ^ ^
| | |
L1 ------* | |
L2 -----------* |
L3 ----------------*
| | |
- - - diodes
^ ^ ^
| | |
--------------------- Return
---- FOR 220 V SINGLE PHASE -----------------------------------------
With a 220 V single phase power supply (P and N coming out of your
receptacle,) as in Europe, Australia, India (?), etc. all you would
need to do is, e.g., put P on L1 and N on L2. That gives 220 V ~
input and if this sqrt(2) rule is correct (which I'm still a little
confused about) you get 220V * 1.414 = 311.8 DC, i.e., just right.
As Leon, the lost wizard of ZA, assures us, the thyristors and diodes
are dimensioned so as to withstand all the power load coming through
L1 and L2 only. If we want to be double sure, it should not hurt to,
say, splice the P (or N) and connect to both L1 and L3. Of course
it doesn't matter where exactly you put P and N and which of those
you distribute over the two input lines. My guts suggest to splice
P on L1 and L3 and N on L2, but that's for no rational reason.
Also, I would not want to miss connecting the protective ground to
the metal cabinet (wherever the protective ground should connect at
the AC input, which I'm not sure about.)
---- FOR US 2 x 110 V TWO PHASE -------------------------------------
For the US I am thinking that may be the 2 phase 220 V dryer hookup
is the best way to go. Not only is this line at a convenient location
where you can store a big cabinet like this one, it is also well
dimensioned to sustain a VAX or (and may be AND) your dryer. Otherwise,
just dry your clothes on a line. But do not mistake the VAX's blower
with your front-loading washer :-).
Seriously, the two phases here, as I understand it, are:
------- P1
------- N
------- P2
with U peek = 110 V and the phases of P1 and P2 being displaced by
180 degree. So, if you measure U between P1 and P2 you get 2 x 110 V
= 220 V. So, I would then connect it like this:
____________________ +300V
| | |
-__ -__ -__ thyristors
^ ^ ^
| | |
P1 -L1 -----* | |
(N)-L2 ----------* |
P2 -L3 ---------------*
| | |
- - - diodes
^ ^ ^
| | |
--------------------- Return
I am not sure whether to use N on L2 or leave N open (again, I
notice how much I forgot about my high school physics.) This actally
bugs me, because I don't know quite where to connect to the ground
potential and how to deal with the protective ground here.
I *think* that when I have the N connection open, I will have a
higher DC output than when I close N on L2. But I don't know.
Can someone throw in his opinion on the matter? I should at least
be able to try this out without being afraid of breaking anything,
since P1 P2 alone work just like 220 V European power. At least,
I am using my old German electric devices on this kind of power
hookup from my 60 A extra two-pase line.
Any comments, warnings, advice?
thanks,
-Gunther
--
Gunther Schadow, M.D., Ph.D. gschadow(a)regenstrief.org
Medical Information Scientist Regenstrief Institute for Health Care
Adjunct Assistent Professor Indiana University School of Medicine
tel:1(317)630-7960 http://aurora.regenstrief.org