Re: X-ray trans circuitry question

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Original poster: DRIEBEN-at-midsouth.rr-dot-com 

Hi Ben,

Maybe I can be of at least a little assitance as I have monkeyed around
with a few x-ray trannies. First of all, your tranyy is a single ended
design which means that the HV side only has one "hot" output with the
other side tied to ground. Most of your 100kV+ x-ray trannies are second-
dary mid-point grounded, with two seperate HV windings, each tied to
ground at one end and the 2 hot ends as the 2 HV outputs. Just like a
giant NST ;^)

As far
 > as I can
 > tell, the hv tranny is supplied with conditioned 220V from the
 > gold
 > transformer (at the leads in the foreground of the center
 > picture)

  This is most likely the autotransformer that controls the input
voltage to the transformer for the different x-ray penetration settings.

The
 > outer winding on the large core is connected via heavily insulated
 > leads to
 > the resistor network.

This is the 60 kV output of the transformer. The "resistor network"
looks like the rectifiers.

Five additional inputs enter the picture
 > here, two
 > attached to the resistors, three go into one winding on the
 > smaller core.

The "smaller core" is the filimaent transformer. It is only rated
for a low voltage (like 12 volts or less) but it is also rated
for at least 60 kV isolation for obvious reasons. You won't need
this part of the system for your purposes.

 >  The resistor bank is attached to a hv capacitor and the short
 > winding on
 > the small core

This is the filtering capacitor to smooth out the ripple of the
the rectified HV output from the rectifier assembly i.e. resistor
bank.

  I'm also assuming the resistors,
 > capacitor, the second core and windings are current limiting
 > circuitry.

Nope, as I stated above, the small cored transformer is strictly
the filament transformer and has absolutley nothing to do with
limiting the current of the HV output. Current (or voltage) limiting
is accomplished by the aforementioned autotransformer.

  The
 > resistor bank, for example, has some  'mystery' devices on it that
 > I've
 > never seen the counterpart to: a yellow plastic 'black box' with
 > two leads,
 > a couple of sealed glass tubes that resemble blown fuses or spark
 > gaps?

Not too sure exactly what you're talking about on this one??
You can pretty much do away with the control box if you have
a large, appropriately rated variac and a current limiter de-
vice, like a one or two 225 amp stick welders, for instance.
I'm sure that you can run this x-ray ransformer at 2 or 3 times
its 3.5 kVA rating since this is obviously the 100% duty cycle
rating of it.

BTW, all x-ray transformers are originally submerged in oil to
operate at their rated voltages and if you intend to operate this
transformer at anything near its 60 kV rating, you'll have to
re-submerge it in transformer oil or it will surely flashover
on the HV winding and become a nice boat anchor.

Hope this helped a bit,
David Rieben