VAX 6000 3-phase conversion (was: Re: Three Phase)

From: Gunther Schadow <gunther_at_aurora.regenstrief.org>
Date: Fri Apr 20 22:39:58 2001

Hi again,

Thanks for those who commented on this power issue.

This evening, I have given it a shot using my spare parts. I took
the box that has the thick 3-phase cable. I opened the rear of that box
and removed this cable in order to attach one that I can actually
plug in somewhere. This is what I saw:


 +----------------------------------------------------+
 | -------------------- |
 | +--------------------+ / GND * \ |
 | | | / \ |
 | | | |Bl* *Br| |
 | | | | Bk* *Bk | |
 | | | +----------------------+ |
 | | | |
 | | | +------------------------+ |
 | | | | | |
 | | | | | |
 | +--------------------+ +------------------------+ |
 | |
 +-----------------------------------------------------+


After opening the cover, the cable is hooked to 5 screws. There is
one yellow/green protective ground wire, even laveled GND. Then
there is a blue (Bl) wire, two black (Bk) wires and one brown (Br)
wire. I probably don't understand this color coding and I was also
surprized to find four not three wires besides protective ground.

I then hooked this up as follows:


 P1 ------------* Bl

                 * Bk
 GND ----------------* GND
                 * Bk

 P2 ------------*Br


that is I connected the protective ground with my protective ground
wire, and P1 to where the blue line used to be and P2 where the Brown
line connected. I left the ex-black connectors open.

Closed the cover and plugged it in. This cover has three control
lights labeled PL1, PL2, and PL3. I noticed that only PL1 was lit.
Then I pushed this T shaped main switch in to engage and using
a potentiometer I checked for AC and DC potentials at about every
receptacle on this box. What I found was disappointing.

I did not find any DC potential anywhere. (I may not have tried
every combination though.) Is it possible that this box does not
have any bridge rectifier in it so all I can expect is AC here
and there? Is there any documentation around what all these many
receptacles are for and how the pins are connected?

Finally, I recognized three standard computer receptacles, you
know, the ones we used to have on PC's power units and where
one would plug in the monitor power. These receptacles look as
follows:
                3
             +------+
            / || \
           | |
           | || || |
           +----------+
             1 2
        
I think what one would expect is that 3 is protective GND, and
1 is Null (N) and 2 is 110 V phase (P) (or 1 P and 2 N, doesn't
matter.) However, that was not what I found. I found that two
of the receptacles has 110 V between 2 and 3 (but not 1 and 2),
and the third receptacle had 110 V between each 1 and 3 and 2
and 3 and 220 V between 1 and 2.

So, something is screwy. I stopped fiddling for tonight. May
be you have some suggestions about what I should do. My plan
is to try connecting things differently, using the two Black
lines instead of the Brown line ... but I'm fairly clueless.

Also, I am not sure I hooked up my circuit breaker box in my
basement correctly. I have one spare 220 V 60 A 2-phase (dryer
hookup) line in my basement. I attached a 2-phase circuit
breaker box as follows:

         B C W R
         L O H E
         A P I D
         C P T |
         K P E |
         | E | |
         | R | |
         | | | +-------+
         | | | |
     +---+ | +--+ |
     | | | |
     | o*oooo*ooo |
     | |
    =*============== |
                       |
                       |
    ===================*


The 60 A uplink line comes with four wires, a black, a red, a white and
a blank copper line. I tested that black is P1, red is P2, white is N
and the copper line's got to be protective GND. As you can see, for
lack of any other connector facility in the breaker box I have connected
the white line (N) with the protective GND line. Should I have done this
differently, like leave the N line open?

However, this shouldn't have an effect on hooking up the VAX, or should
it? Would I not need to connect some N wire so that those receptacles
are powered correctly?

any thoughts appreciated,
-Gunther
Received on Fri Apr 20 2001 - 22:39:58 BST