Re: Good Deal? SURE !!

Hi Bob,

Let me take a stab at this thing. My comments are

>I had an opportunity this week to purchase a couple of items from an
>electronic scrap dealer ( I had purchased a used lab vacumn from him
>had asked to keep his eyes open for a variac ).
>He had two variacs ( 10amp )beautifully mounted in an aluminum box with
>plug inlets/outlets.
>The second item he had was a high voltage power cabinet. This is the
>item I'm hoping you more experienced engineers or physicists could help
>me with.

You lucky guy!! I remember a few places in California, where you could
get loads of interesting electronic "junk" (more like jewels).

>It has a giant transformer (I'm guessing a potential xfrmr?) that
>a couple hundred pounds. It has three sets of coils apparently vacumn
>impregnated plastic of some kind. The output is rated at 15KV/150mA
>(yes!), but it looks set up for DC output. inside the box, a circuit

Three sets of coils = I willing to bet it is 3 phase (2.25kVA).

>board is bolted to the sides of the coils with bolts that I assume are
>connected to the secondary? On the circuit board are six diodes (well
>six similar sized pieces - 3 have a diode sign, 3 don't) all hooked up
>in parallel (3 are marked BCD 25, 3 are marked EDI 8036).

Yes, this is DC. This is a typical 3 phase rectifier. BCD 25 ist a
diode for sure. The EDI 8036 doesnīt tell me anything, tho.

>board they are connected to a .1 uF capacitor rated at 20KV DB 4180 (no
>indication if rated at AC or DC voltage). It also had a rating of ER
>200-104 ( don't know what this means). It does appear that one terminal
>of cap goes to HV terminal, other goes to ground? which is another
>indication to me it's a DC output.

I am willing to bet it is a DC cap. If the unit is an older model, then
DB could stand for "Deutsche Bahn" (german train company).
The DB used to have parts specificly made for them (hence
the "DB" number). What bothers me is the discrepency (sp?)
in the voltage rating (15kV x SQRT(2) = 21.xxkV). The cap
would be overvolted. Sorry, "ER" doesnīt mean anything to

>The whole thing is controlled by 3 220V Variacs hooked up in parallel
>(I think). On the front cover is a digital readout of output
>voltage/current, on/off HV, Variac dial 0-100, on/off vacumn, on/off

Hmm. I think the variacs should be connected in a Y (star)
configuration. N is in the middle, the three phases attach
to the "outsides" of the Y. Are the variacs mounted on a
common shaft (should be the case in a 3 ph. setup)?

>Lastly, the input shows  380/220/2.4Kwatts!? and says 3 phase + neutral
>under that. How is this possible? 15KV*150mA=2250 watts. Where do they
>come up with a 2.4 Kwatts rating?

This DEFINATELY sounds like a european setup. In USA
they use (if I remember it correctly) 120/208V in 3 phase
setups. The difference between input and output isnīt
that large (2400W-2250W = 150W). This could
accomodate for losses or the VA for the vacuum and
water pump (sws = vacuum/water on/off)

>1] Can anyone tell me where this might have been used? Maybe a laser or

Whew, that is a hard question to answer. It might have even been used
for a small linear accelerator. Does the box or components inside have
any markings (other than the ones you mentioned)?

>2] Assuming it's DC output, can I hook it to my existing 6.5 inch TC
>with added caps to match 150 mA rating? ( currently running 15K/60 mA
>NST) Or what modifications are necessary to run it using this setup?

You will need a charging reactor in series with the psu (secondary
side). The schematic for a DC TC (bad ryhme) will be very
similar to your AC TC. The question is also how much PIV will
the diode stack take. Best bet is to ask Greg Leyh about this.
He is the DC TC expert.

>3] I'm thinking I can always use just the transformer, if I wanted, and
>disconnect the diodes and cap, and run it in my primary tank circuit.
>Is this right?

YesNo. As this seems to be a 3 phase xformer, each phase
only needs provide 1/3 of the total power. So the transformer
really is a 3 in 1 unit with 50mA per unit. However the three
phase setup (transformer design) wonīt let you parallel the
transformer alone (AC paralleling), due to the phase shift
(120°) from phase to phase. So if you want to use it, you
will need three phase input and use the rectifier setup.

>4) Being that the input is rated at 380/220, is there a problem hooking
>it up directly to my 220 dryer outlet? Do I need to modify or jumper
>anything on the transformer to get it to work properly with 220V only?

YES!! You need three phase input power. The 220V, you have,
is simply 2* 120V on a single phase. The 380/220V sign tells
me it is a Y configuration. 380V across to phases and 220
from each phase (R S T) to neutral. If it where a delta
(triangle) configuration you wouldnīt need neutral and the
plate would simply read 380V 3 phase.

>5)My first coil is powered by 15k/60 mA NST (900 watts). What can I
>expect in performance increase with this monster as opposed to
>increasing my NST to 120 mA?

None (without three phase input) (:o(x).
(sorry, couldnīt resist this answer).

>I know this is a long post, and if Terry wants to keep reply's offlist,
>that's fine. I got too good of a deal on this baby, couldn't turn it
>down ( total for HV box and 2 other variacs - $100.00! ).

2 variacs + 3 variacs in the box plus a .1ĩF cap for a hundred bucks
is a great buy. So even though you (probably) canīt use the 3
phase xformer, you still got a great deal.

>Any help is GREATLY appreciated.

Well I hope this helped and I didnīt disappoint you too much.

Coiler greet from germany,