Re: Re-configuring X-Ray Transformers

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

Original poster: "Kristian Ukkonen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kristian.ukkonen-at-iki.fi>


Tesla list wrote:
> Original poster: "Loudner, Godfrey by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>
> There's a heck of a lot of wire in those HV windings, making for much
> impedance. You would need 100kV impressed on the HV windings to circulate
> the normal full-load current of 400 mA. The 20,000 volts is not enough to
> overcome the impedance to circulate a current of 2 amps. Turns must be
> removed from the HV windings to lower the impedance.

My biggest x-ray transformer (weight >200 kg without oil, dimensions
of oil tank about 1m*1m*1.5m, had two cx5184 100kV 2kW triodes etc.
goodies) 
that I have disassembled, has VERY thick secondary wire. Something like 
0.5 mm dia.. Also, the secondaries were freely configurable either star
or
delta - as well as primary. The secondary coil outer diameter was about
25cm..

Often, when size is not a constraint, quite thick magnet wire is used
for secondaries to get large radius for wire and easy to wind. 
After all, dimensions are large anyway because of the voltage (>200 kV).

As well, these kinds of human-exposure x-ray machines are built to
give very brief exposure (they use rotary anode x-ray tubes!!),
so they have to handle large current for a while. They are NOT run at
average current but always at peak current for a few seconds at a time!
For industrial radiography, the machines and transformers are for
average current and long exposures, and of different contruction
with thin wire secondaries etc. to get them as portable as possible.

> Was it costly to get two x-ray transformers together with their control
> panels. There are many useful devices in the control panels.

I have got many for scrap price of iron from junk yards,
without oil, of course. The older ones are dumped all the time.

I have VERY large variac too from the control panels.
Largest is >100kg weight 3-phase beast. Wire is about 1.5mm*15mm
form wire. Has to handle the large instantaneous current too
during short exposures, but about 0% cutycycle at longer intervals.

  Kristian Ukkonen.