Re: x-ray transformer questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jack Vandam" <snotoir7674g-at-mindspring-dot-com> 

Thanks for the info.  Unfortunately, I wouldn't be able to obtain the
measurements you speak of without opening up the transformer.  Not knowing
for sure whether or not PCBs are present, it's going to stay closed until I
find out for sure.  However, I will save this info for future reference in
the event I do open up the transformer.

Jack

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, September 25, 2004 1:47 PM
Subject: Re: x-ray transformer questions


 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 >
 > Most of the larger units, such as yours, have a 7.5 - 10 kVA core.
Measure
 > your core dimensions and I can give you a better estimate.  Core cross
 > section is one of the most important factors with regard to the magnetic
 > flux.
 >
 > The 7.5 - 10 kVA rating is approx 75% duty cycle but can be exceeded for
 > short periods of time such as charging up large Marx bank caps, etc.
 >
 > If you plan to run it constant, they you would be wise to operate at 5-6
kVA
 > as a maximum.
 >
 > The reason the power levels are not specified is because different types
of
 > buck/boost reactors (external) were used with these xmfrs, so ratings
depend
 > on heat rise vs. time.  You could determine the proper rating by operating
 > the xmfr in sec short circuit condition and carefully monitoring the core
 > temp with a thermister.  Many modern multimeters have these probes.
 >
 > Core temp vs. time will give you a reasonable estimate of how much power
you
 > can operate at.  Core temp should not exceed 180 degrees F. (max) for most
 > applications.  You can carefully dry off a section of core and wipe clean
 > with a solvent.  Then, using conductive epoxy, attach your thermister.  Be
 > sure to keep this conductive epoxy away from the HV coils.
 >
 > Keep the core temp below 175 degrees F. with long run times and you should
 > be ok.
 >
 > This was our approach on a large X-ray xmfr we used to charge a 100 kV
Marx
 > bank.  It worked out to approx 12.5 kVA for short duty cycles less than
25%.
 >
 > Be extremely care --- these things are killers.  We attached a large red
 > rotating beacon to one side of the 220 to ground (120 VAC) so the beacon
was
 > on any time HV was on.  Use a relay so it will energize as soon as your
 > control circuit applies any voltage to the primary of the xmfr.
 >
 > Dr. Resonance
 >
 >  >
 >  > Tonight's questions concern a Westinghouse x-ray transformer.  There
are
 > two
 >  > things I'm wondering about with this unit: its specs and input/ output
 >  > information.
 >  >
 >  > Here's what's on the label:
 >  > cycles 50/60
 >  > wiring 3D 8939
 >  > style 981928
 >  > Volts AC, KVA, and Amps are all blank.
 >  > Under the word "Westinghouse", there are the following tiny numbers:
 > 36233-D
 >  >
 >  > Can anyone figure out the complete specs with this info?
 >  >
 >  > Now for the input connections:
 >  > XFL, XFC, XFS, G, MA, A, AA
 >  >
 >  > Input hookup info?
 >  >
 >  > And, finally, there are two high voltage recessed terminals.  One has a
 >  > single center conductor; the other side has three (their purpose?).
The
 >  > diameter of the sockets is 1.25".  I did manage to obtain some high
 > voltage
 >  > cable at one point, but the end diameters are too large.  I'm
considering
 >  > making new ends out of epoxy or if I could obtain the correct size
cable
 >  > economically, I would go with that.
 >  >
 >  > Dimensions are about 13.5x17x15 inches and it must weigh at least 250
lbs
 > I
 >  > would guess.  Not sure what I'm going to use it for, but my purpose
right
 >  > now is to just find out about it and get it going, using an appropriate
 >  > variac for current limiting of course.
 >  >
 >  > If anyone has any info on this or a similar unit, I would appreciate
your
 >  > sharing of it.
 >  >
 >  > Thanks,
 >  > Jack
 >  >
 >  >
 >  >
 >
 >