High Voltage Forum

High voltage => Transformer (Ferrite Core) => Topic started by: nielsquake on July 25, 2020, 06:16:01 PM

Title: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 25, 2020, 06:16:01 PM
I have bought this transformer for a reasonable price and I was unable to find much using the product number: 451210494553. I know where the HV outputs are but I have no clue if this is even a ferrite core type transformer. I have a 1500w zvs driver and I was wondering if this would do the trick to run it. Does anyone know how to read this pinout and know which pins correspond to the primary of the top output? Also I want to know if this is a ferrite cored transformer or an iron core (https://i.imgur.com/xD5wbDq.jpg)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 25, 2020, 08:56:28 PM
Hi Niels and welcome to HVF!

From the look of it, it is a modern ferrite core transformer, seems newer than any I have found.

It is about as big as one that I found in a 70 kW system that had two SKM400 IGBT brick inverters, it was either running them interleaved or just one for low power and two for high power, I am not sure.

What DC resistance measurements do you get between X1001, 1002, 1003, 1004?

It could be two primary coils as some of the transformers are divided in a positive and negative part and the mid-point is grounded. The mid-point would in that case be a bridge through which you measure the output current, as it is at ground potential there is no problems with measuring it with a simple shunt resistor.

The voltage feedback interfaces are more modern than what I found, but you properly just have outputs for negative and positive voltage, temperature and pressure in the tank.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 25, 2020, 09:16:40 PM
Hi Niels and welcome to HVF!

From the look of it, it is a modern ferrite core transformer, seems newer than any I have found.

It is about as big as one that I found in a 70 kW system that had two SKM400 IGBT brick inverters, it was either running them interleaved or just one for low power and two for high power, I am not sure.

What DC resistance measurements do you get between X1001, 1002, 1003, 1004?

It could be two primary coils as some of the transformers are divided in a positive and negative part and the mid-point is grounded. The mid-point would in that case be a bridge through which you measure the output current, as it is at ground potential there is no problems with measuring it with a simple shunt resistor.

The voltage feedback interfaces are more modern than what I found, but you properly just have outputs for negative and positive voltage, temperature and pressure in the tank.

Hey, thanks for the response. My multimeter is busted right now but at least knowing I got a ferrite core one assures me that I can probably get it working with the propper equipment. Would a 50khz zvs driver work to power it? 
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 25, 2020, 10:55:00 PM
From what I have observed in the xray inverters I have taken apart, they have a large 3-5uF capacitor in series with the primary winding, effectively acting as a DC blocking capacitor as its not driven at the LC resonant frequency and that is how the output voltage is controlled, by changing the drive frequency and the current by the on-time or pulse train lengths.

I would guess that 50 kHz is in the high end of what these are designed for, but that is merely a guess.

Maybe there is some information of value to you from this Steve Ward project: http://stevehv.4hv.org/ccps1.htm

Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 26, 2020, 02:53:01 PM
Okay, So the circuit blocks signal that are not high frequency then? I am looking into doing some trial and error with this after I get a new multimeter and I hope to get it up and running using one of those high wattage chinese drivers. I got this transformer from a medical supply company by doing some sweet-talking and I think I got pretty lucky so I wouldn't want to ruin it.
The coil itself has never been outside of the oil so am I right in assuming that hooking it up to a ZVS that is powered under 1000w wouldn't burn any of the internal components or mess with that DC blocking cap you were talking about? This whole thing is pretty advanced from what I normally do (Primarily using NST's and flybacks with the 505 timer circuit) I have powered TV flybacks with a ZVS and I think the same principle goes for these big flybacks right?
I want to be able to drive a full 1000w into it and I really don't want this baby to break. It just looks so epic and I can maybe one day use it to do some DIY magnetron sputtering so I can examine objects from home with the SEM at my uni :D
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 26, 2020, 09:24:07 PM
The series capacitor is outside of the tank, it is part of the inverter. You can see them sit in series with the primary output leads from the two IGBT full bridges in this setup: http://kaizerpowerelectronics.dk/tools/file-archive/?drawer=images*junk_yard_stuff*2015_12_23_-_xray_philips_optimus_65 (http://kaizerpowerelectronics.dk/tools/file-archive/?drawer=images*junk_yard_stuff*2015_12_23_-_xray_philips_optimus_65)

This x-ray transformer is designed for 65 kW input power, 1 kW can still do damage if you connect it wrong, I still think you have a very similar transformer to the one I found there, where it used two full-bridge inverters.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 27, 2020, 12:19:25 PM
The series capacitor is outside of the tank, it is part of the inverter. You can see them sit in series with the primary output leads from the two IGBT full bridges in this setup: http://kaizerpowerelectronics.dk/tools/file-archive/?drawer=images*junk_yard_stuff*2015_12_23_-_xray_philips_optimus_65 (http://kaizerpowerelectronics.dk/tools/file-archive/?drawer=images*junk_yard_stuff*2015_12_23_-_xray_philips_optimus_65)

This x-ray transformer is designed for 65 kW input power, 1 kW can still do damage if you connect it wrong, I still think you have a very similar transformer to the one I found there, where it used two full-bridge inverters.
So the IGBT inverters generate the high frequency? Do I need to supply the main input pins (X1001, 1002, 1003, 1004) with just straight DC or pulsed DC or AC? I'm still pretty confirmed. I'm new to this. I just bought a new multimeter so when I get or I can get you the resistance of the pinouts. I currently only have a DC power supply of 150w so I'm not sure if that is even high enough to provide any output al all. Is there any foolproof way to power one of these that is pretty straight forward for someone like me that's lacking a lot of knowlage about these kinds of circuits
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 27, 2020, 01:12:24 PM
The contents of the xray transformer tank is rather basic. It is a split step-up transformer with high voltage rectifiers and a voltage multiplier output stage.

The drive frequency is from the inverter and its driver circuits. The output of such a inverter is a pulsed DC square wave of some frequency that will result in a AC sine wave in the LC circuit of the capacitor in series with the primary coil.

You should be able to drive this with a ZVS driver, you could always add something in series with the main supply to limit the current, like a heating element or bulb. Something like a simple TL494 driver could also be a good way to experiment with low on-time and duty-cycle: http://kaizerpowerelectronics.dk/high-voltage/tl494-flyback-driver/

Getting the full potential out of this transformer will however require a large inverter with a serious DC bus to deliver pulses of 65 kW, considering you most likely only have 3x400VAC at 16A available.

A multimeter is great to check things, but to troubleshoot driver and inverter for a project like this (safely) you need a oscilloscope, current transformer and differential probe.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 27, 2020, 10:36:26 PM
I found out this is a 2 tube transformer so I think it contains 2 full-on flybacks. The 4 pins must correspond to the 2 primarys for those I think.

The contents of the xray transformer tank is rather basic. It is a split step-up transformer with high voltage rectifiers and a voltage multiplier output stage.


The drive frequency is from the inverter and its driver circuits. The output of such a inverter is a pulsed DC square wave of some frequency that will result in a AC sine wave in the LC circuit of the capacitor in series with the primary coil.

You should be able to drive this with a ZVS driver, you could always add something in series with the main supply to limit the current, like a heating element or bulb. Something like a simple TL494 driver could also be a good way to experiment with low on-time and duty-cycle: http://kaizerpowerelectronics.dk/high-voltage/tl494-flyback-driver/

Getting the full potential out of this transformer will however require a large inverter with a serious DC bus to deliver pulses of 65 kW, considering you most likely only have 3x400VAC at 16A available.

A multimeter is great to check things, but to troubleshoot driver and inverter for a project like this (safely) you need a oscilloscope, current transformer and differential probe.


Thanks this really helps a ton
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 30, 2020, 09:50:16 PM
I did the resistance measurements of the inputs and it turned out to be 1.4Ω between X1001 and X1002 and 0.6Ω between X1003 and X1004. Given that the measurements were possible I assume this means I can drive it straight with a ZVS connected to X1001 and X1002 without much of a hassle right? I imagine these correspond to the output of the secondary that already has the HV Xray standardized connectors installed as this seems like the main one just judging from how the device looks and I imagine this one should have the largest resistance on the input.
(https://i.imgur.com/fQZSeCj.jpg)

As you seem like one of the most knowledgeable people on this topic around here on the internet I would love to hear your opinion on if this would work Kaizer.

I made a video that I also show the device in if you're interested :)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 31, 2020, 12:13:43 AM
Could you get a reading between X1002 and X1003? and what about between X1001 and X1004?

I really wish I had gotten some pictures of the inverter connections of that large system I found, but I got nothing.

I found this short video and it seems there is only two primary wires going into the terminal housing of the transformer
/>
You could be lucky to find a manual that can give you hints of the connections, somewhere among there, despite most of it is older stuff: http://www.frankshospitalworkshop.com/equipment/x-ray_service_manuals.html

Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 31, 2020, 12:38:28 AM
Could you get a reading between X1002 and X1003? and what about between X1001 and X1004?

I really wish I had gotten some pictures of the inverter connections of that large system I found, but I got nothing.

I found this short video and it seems there is only two primary wires going into the terminal housing of the transformer
/>
You could be lucky to find a manual that can give you hints of the connections, somewhere among there, despite most of it is older stuff: http://www.frankshospitalworkshop.com/equipment/x-ray_service_manuals.html

No readings between those pins, I tested all combinations and those were the only two places I could get a reading including the grounded exterior of the transformer case.
Those resources are a very nice find. That video seems to be almost exactly the same type so that's lucky. No luck finding a manual though, I've tried but I couldn't come up with anything. I keep wanting to just hook it up and try but burning out the coils is the last thing I want so I'll just continue learning about how this all works internally. I contacted a US based supplier and they aggreed to take one apart for me and get the components out of the oil. The guy will send me pictures from all sides and will try to confirm a few things for me so when I get those I'll share them here.
What would you say is the minimum ammout of power a DC power supply should have to power the ZVS and in turn this transformer?
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 31, 2020, 02:33:30 AM
I also found this pic (https://pt.dotmed.com/images/listingpics/1849953.jpg)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on July 31, 2020, 10:51:47 AM
No readings between those pins, I tested all combinations and those were the only two places I could get a reading including the grounded exterior of the transformer case.
Those resources are a very nice find. That video seems to be almost exactly the same type so that's lucky. No luck finding a manual though, I've tried but I couldn't come up with anything. I keep wanting to just hook it up and try but burning out the coils is the last thing I want so I'll just continue learning about how this all works internally. I contacted a US based supplier and they aggreed to take one apart for me and get the components out of the oil. The guy will send me pictures from all sides and will try to confirm a few things for me so when I get those I'll share them here.
What would you say is the minimum ammout of power a DC power supply should have to power the ZVS and in turn this transformer?

That is nice, often it is very hard to get information from the companies on single parts without a service agreement.

You could properly power this from 50-100W at a very low duty-cycle, will get you some high voltage at very low current. The transformer you have is a beast and it will easily eat 65-100 kW peak, so continuesly (5-10 minutes) it could properly run 10-20 kW without cooking the oil, see if you can find the temperature measurement points on the control boards.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 31, 2020, 05:38:49 PM

Made some extensions for the HV plugs using NST wire and some garden hose that I filled with wood glue around it to seal it completely

(https://i.imgur.com/ZbCclAX.jpg)

The wire was snipped of so short that I had to angle grind some of the aluminum plug housing off completely to expose part of the wire with the insulation intact.
Tested the plugs by connecting them to my flyback and a microwave transformer to see if it would arc through and it seemed to work fine.
I'm getting my 1kw max output ZVS driver tomorrow so I'll probably do some short tests shortly to see if it works the way I think it does.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 31, 2020, 06:15:27 PM
Oh and I just called the supplier I was talking about and he claimed that this unit has the inverters installed in a separate container from this transformer box. If this is the case I assume this might make it easier to drive right? as the ZVS should adjust the frequency accordingly to the resonance or something like that and there isn't any hardware in front of the primary?
Maybe 2 pins of the 4 pin input just correspond to the filament transformer?
Also he told me this one was rated for 80kW so that is good to know!

BTW I now realize that you meant this system was driven by these IGBT inverters from an external source (I saw your video on that specific transformer you were pointing out and you showed the inverters inside the separate enclosure) I was just slightly confused but now it's a lot more clear to me how the internals are wired up. I just assumed that you meant the inverters were under oil with the flyback and that it was all part of this one unit so that is why I was confused on how to drive it...
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on July 31, 2020, 07:32:09 PM
Now that the glue is dried it looks pretty nice:

(https://i.imgur.com/o523X9p.jpg)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 02, 2020, 06:58:34 PM
Hell yeaaa, it works!


This is 135W input from laptop charger but it looks like the output is just fine :D  8) 8)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 02, 2020, 11:45:38 PM
Test with a little bit more voltage. it seems to be less efficient then a TV flyback with this weak input power (arc is about half as long) but it makes me happy to see a nice arc comming from a machine like this :D


Oh and the primaries are not center-tapped in these kinds of transformers right? Since it runs fine with just these two inputs (the red and blue one)
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on August 03, 2020, 08:21:26 AM
Oh and the primaries are not center-tapped in these kinds of transformers right? Since it runs fine with just these two inputs (the red and blue one)

Congratulations on getting it to run! I have 2 x-ray transformers that still sit untested in my workshop :o

I have only seen x-ray transformers with single or split primary coils (driven by each their being either negative or positive), but not any center tapped.

The secondary winding is however center tapped, so you should be able to locate the center bridge and you can use that to measure the secondary output current with a correct size shunt resistor or maybe even a clamp on meter
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 03, 2020, 05:02:26 PM
Thanks! I wouldn't even have tried without your help!
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 17, 2020, 11:29:12 PM
Okay, so the supplier that was going to help me get pictures ended up not sending anything, so I decided to do a teardown myself to see what's inside. Now I found some weird stuff when looking inside.

In the beginning you can see what appears to be 2 smaller flyback transformers. There is also one big round transformer that has a whole bunch of components around it. I had to lift this all by hand so I asked my mom to film it for me so I could look at it after filming, but this made me unable to check where all the cables are wired up.

Which one of these transformers is responsible for the H.V. output and what is the other one for? Is there anything notable in here that could identify what kind of max output is possible with this?

I kind of want to remove the internal capacitors and diodes so I can get a high frequency AC output from it and make it more manageable size wise but I'm hoping you can advice me on if this is a smart idea.

I took the top of it like this for about 5 times exposing the internals to air, is it necessary to pull a vacuum on it now or should it be fine having just been outside of the oil for less then a minute.

I hope my questions make sense, looking forward to a reply  ;D
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: johnf on August 18, 2020, 10:32:40 AM
The two smaller transformers are series connected filament transformers to get the required standoff voltage ie one drives the other.
you have taken it out of the oil and also exposed the oil to water laden air.
from what i saw of the bits next to the big ferrite cored transformer are the multiplier stacks.

hope this helps

ps do not drive it anywhere near its max voltage until you revacuum the windings to get the air out
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Mads Barnkob on August 18, 2020, 01:11:26 PM
I agree on the smaller flyback core transformers are the filament transformers.

You can see PCBs with lots of series connection diodes at the end of the large transformer, these form the center-tapped voltage multiplier with the red wires going from the two brown capacitor towers in each side. If you want a AC output, you need to remove the capacitors and diodes.

There certainly is a risk that you now have air bubbles sitting on the underside of things, but you did not have it up long enough for oil to have gotten out of all windings and form air tiny air bubbles without there is still a layer of oil on the parts. Re-vacuum is the only way to be sure.

Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 18, 2020, 10:22:24 PM
Thanks yall, that's kind of what I assumed too but there is no visible output for the filament transformer but I guess it's on one of the PCB's.
I am gonna buy a two-stage vacuum pump so I can suck it down. Does it need a deep vacuum? The pump I'm gonna buy is gonna be pretty strong so I imagine I shouldn't go to it's maximum.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 19, 2020, 09:04:50 PM
I ordered the pump and it is rated at around 5pa. I doubt that it really goes that deep but let's hope so I can do some fusion stuff in the future. So my plan is just to run the pump connected to it for around an hour and then disconnect it, is there a risk of the container damaging this way? I imagine because of the oil the compressible air in the systems is just a few liters so I imagine the strain on the container would be pretty minimal.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: davekni on August 19, 2020, 09:27:25 PM
I have no idea if the case can handle vacuum or not, but the remaining amount of air isn't relevant.  During evacuation, you will either have some vacuum space on to of the oil, or you will pump out some of the oil, until pressure reaches your pump's capability.  If the container walls collapse in the process, you will just pump out more oil.

I'd guess that the transformer was originally filled inside a larger vacuum chamber holding the container internally.  Hopefully others here have more specific information.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: johnf on August 19, 2020, 09:58:33 PM
A tank your size would need reinforced sides about 10mm thick or more
if it is not that thick then it is a Dave has said you need a bigger chamber to put it in

I did this with my SEM microscope HV tank after service i used a short length of steel pipe 1m long 900mm in diameter welded end and a flanged top with 20mm plate lid.
has proved to be very useful since vacuum potting transformers de-airing epoxy etc.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 20, 2020, 01:27:07 AM
Hmm, sucks I won't be able to vacuum the whole thing down but I was thinking about getting the transformer out and putting it in a smaller glass container anyways. Now if I went about doing this, would the output side be the center tap of the secondary? Is it easy to wire it up in a glass container like that and does it need grounding anywhere?
I am gonna use a thick solid glass fishbowl so I can pull a vacuum on that and just fill it up with the oil from this tank. Maybe I'll try keeping the rest of the components attached in the original container and I can just use it externally when I need a DC voltage for anything. I hope it's not too hard to remove the transformer but I think I'll manage. I'm thinking about just lifting the whole setup out of the box like I did in the video and place it between some chairs or something more solid so it can lean on that and I can access the components easily. Do any of the other components also require to be vacuumed down? I imagine air doens't trap nearly as much in the voltage multiplier compared to the secondary windings.
Thanks for the detailed responces btw yall. Oh and Johnf, sweet workshop mate  :o
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 20, 2020, 01:40:10 AM
Oh and if I use an ungrounded glass container, would that cause dielectric charge buildup on the transformer? Maybe I can partly cover the bottom with aluminium foil and tape that on there with a ground wire to prevent charge buildup on the outside or will discharging it normally by touching the anode and the cathode be enough?
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: klugesmith on August 20, 2020, 03:34:58 AM
Not sure about XRT's, but utility transformers with 6-digit voltage ratings generally have tanks reinforced to withstand full vacuum.
I think that's normal for pad-mounted transformers handling only 5-digit voltages, but am not sure about that.
Did you notice any internal reinforcement when you had it open?

Linked document gives a representative procedure:
Close off accessories that are not resistant to full vacuum.
Evacuate main tank without oil, to absolute pressure < 2 mbar.  Hold 12 to 36 hours depending on mfr's requirement.  (In transformer factories sometimes the windings are heated during this phase.)
Admit processed oil from the bottom of tank. (Primary degassing and drying of oil is done outside the main tank.)

https://www.seamarconi.com/en/services/filling-the-transformer-with-oil/

I guess you could experimentally apply a partial vacuum inside your transformer box, and see how it responds.
The flat sides ought to go detectably concave, and you can guess if the amount of distortion is scary.
Not like sphere or cylindrical tanks under external pressure, where failure by buckling can be sudden and dramatic.

Sanity check:  online calculators for deflection of flat plates with uniform loading.  For a box whose edge connections are stiff, I think "fixed edge support" is a better model than "free edge support".  Anyway, a starting point was round plate, 0.3 m diameter, steel 5 mm thick , 100 kPa load pressure. 
Fixed edge:
  center deflection 0.35 mm, max stress 44 MPa according to 2 different sites.
Free edge (an excessively conservative model):
  center deflection 1.4 mm, max stress 111 MPa according to one site.   Not even close to yield stress (~400 MPa), so it will completely spring back when unloaded.
[edit] couldn't keep away.  Here's a ref that says 0.3 m square plate with clamped edges (i.e. corners of box don't act like piano hinges),
only 3 mm thick, could withstand full vacuum with deflection of about 2 mm, and spring all the way back.
https://www.engineersedge.com/material_science/uniform_load_rectangular_plate__13644.htm


Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 20, 2020, 12:45:29 PM
Sadly the inside lacks any reinforcement. I could try tigwelding square support beams all around it but I think this might be a bit too much extra work. I think this container was filled in an external vacuum like davekni proposed as the walls are easily pushed in by hand.
The oil level is very high so if the walls were to all be compressed it would for sure push out the oil from the top.
Now a vacuum chamber that might fit this whole box is just a tad excessive for my needs so that's why I'm looking into using a glass container.
Thanks a lot for the info btw, the procedure that is explained on that link is kind of what I have been looking for but unable to find!
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: davekni on August 21, 2020, 06:01:44 AM
Is your glass container designed for vacuum?  Even a thick glass container can be hazardous to evacuate if not intended for vacuum.  Glass is very strong in compression, but weak in expansion.  Vacuum containers are designed to keep all the glass in compression.  Random glass containers, especially with any flat portion, will end up with some glass in expansive tension.  This can lead to implosion failure and likely some shards of glass headed your way at high speed:(
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 25, 2020, 02:10:20 PM

Okay, so I got the main transformer out with a lot of effort and now you can easily see where all the wires go. the big brown cables that go around the ferrite are the primary input and the 4 red wires appear to be the output that leads to the capacitor towers but I have no clue which output is which and how to connect them up before relocating to another container. There seem to be 8 very thin brouwn wires going into those PCB's with the diodes so I presume these are the outputs. how would I go about connecting these up to get the highest possible AC output and why do there appear to be 4 primary inputs? Are there also 2 secondaries then?

(https://i.imgur.com/X4ZlOyG.jpg)
This image explains the wireing a little bit better

I'm glad I got it out because it's pretty impressive holding such a large flyback
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 25, 2020, 08:45:57 PM
So I get how this whole rectification process is supposed to work but I can't wrap my head around how to connect the 8 small output wires. I kinda hoped there were just 2 lol but yea. It seems like there are a whole buch of small secondary coils that comprise the whole transformer but I'm honestly not sure. Now I also think there must be 2 primary coils because of the 4 input wires.

(https://i.imgur.com/eT209o9.jpg)

In this pic you can see the 4 input wires. I marked the red and blue one as these were working for me to get an output when it was still assembled but I'm pretty sure the other 2 also serve as an input side. Now as you can see in the old pics the transformer had 4 output plugs total and it was advertised to be able to run 2 xray tubes at once so I wonder how this works and how the output is chosen. It also almost looks like the 2 middle wires are connected but I couldn't get a resistance between those 2 so I guess they're not.

(https://i.imgur.com/aC6BCUA.jpg)

Here you can see how the little output wires go from each of these cylinders (I assume are the secondary windings) Each of those coils has only one wire attached and they alternate which side the come out of to the PCB. In this image I've indicated how the 2 wires from 2 of the coils connect to the diodes and which coils connect to which diode PCB. As you can see the coil I've marked with #1 is connected to the right side of the left most PCB and the coil I've marked #2 comes out at the left side of the left most PCB. Keep in mind this pattern repeats like this even though the polarity of the PCB's seem to be alternating in polarity for the diodes so the layout on each PCB and the connection points are the same but the polarity of the diodes is flipped (from left to right +-+-) like a mirror image.

(https://i.imgur.com/sb3cga7.jpg)

So assuming I'll only use the 2 inputs I marked blue and red. how would I go about soldering the outputs together? or am I thinking about this all wrong? Is it even possible to get AC output from this?
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: SteveN87 on August 26, 2020, 11:27:44 AM
Is that core really ferrite? Looks like it might be Metglas tape:

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Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 26, 2020, 01:57:13 PM
It probably is a tape wound core yea I agree. That doesn't change much about the functionality right?
Is metglas preferable to ferrite when driving the core with high frequency?
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: davekni on August 26, 2020, 06:11:56 PM
There are several materials used for tape-wound cores.  Metglas is a likely candidate here.  High-frequency performance depends on thickness of the tape as well as material.  Metglas is used up to 20kHz or slightly above.  It can handle higher flux density than ferrite, around 3x saturation flux.  Cure loss gets higher than ferrite as frequency rises.

For large high-voltage transformers, winding capacitance limits upper frequency, so metglas makes sense as a design choice.  Probably ran in the 10-20kHz range.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: klugesmith on August 26, 2020, 06:48:14 PM
Most tape wound transformer cores are made from ordinary silicon steel in strip form.

I think Metglas and other amorphous metals are distingushed by extremely thin laminations (25 um or 0.001 inch).
Their saturation induction is much higher than ferrites, as Dave said, but lower than ordinary steel.

Nice thing about high frequency: you can get plenty of volts per turn without having to push B_max.
But need to mind core loss. Thin laminations or electrical non-conductivity reduce the part from eddy current, not the part from hysteresis.
Maybe not too important in radiography applications, where tube anode heat limits the duty cycle to a few seconds in any 5 minute interval.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 26, 2020, 07:19:11 PM
Hey thanks for the replies! Before I took it apart the output was pretty good from a 36V lithium battery as seen in this video here
I honestly didn´t know that flybacks were also made of metallic iron too as opposed to ferrite but I was able to run it just like an ordinary flyback with my ZVS driver so that´s cool to know.
I still have no clue how to connect the wires to get AC output though and I still need to find a propper chamber that can handle a vacuum and fit this transformer. I´m thinking about 3d printing a base that fits exactly in the container that fits the transformer so it stands upright in a stable position. Pretty cool idea of having it show in a glass jar just being held at the bottom with the 3D print. I hope someone can assure me that this is possible because I really wasn´t expecting this 8 secondary coil design kind of deal  ???
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: SteveN87 on August 26, 2020, 08:12:25 PM
The ZVS is forward converter - actually a Baxendall converter. It doesn't rely on core saturation to commutate, so is actually a  good match for your transformer. A true flyback converter requires an air gap in the core to store energy. Non-gapped cores will quickly saturate when driven to any appreciable power with a true flyback driver like the one I use (peak current/constant off time). Examples of flyback transformers are LOPTs and automotive ignition coils - your transformer is not a flyback.

Those arcs are very impressive!
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Teravolt on August 26, 2020, 09:22:31 PM
what is your supply voltage beacaus you have a lot of current but not very much voltage, maybe 5KV -10Kv. if that is a x-ray transformer it is capible of an arc 3x bigger or more. maby a igbt brick half bridge setup running off the mains will get you there
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: johnf on August 26, 2020, 09:47:33 PM
by golly
you will be the late Nielsquake if you start holding wires like that
one moments inattention and pick up the wrong wire and it will fatally bite you when the insulation punctures through

BE CAREFUL
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 26, 2020, 09:58:01 PM
Yea so I am planning on upgrading the input side as the ZVS driver can only handle so much but I still don't know how to wire up the secondary coils together. Is this transformer able to output AC voltage at all or does it require for the voltage to be rectified and dumped into the capacitors. As it seems like there are 8 coils do these even work in phase? I drew up a crude diagram of how it's wired up so of anybody understands how I can connect all the coils together it would be greatly appreciated because I'm starting to feel bad I took it apart in the first place lol. It is awesome though, seeing how all the internals are engineered turns out to be way cooler than looking at voltage arcing   ;)
Well here goes my attempt at drawing how it's wired up
 (https://i.ibb.co/tCSbfn2/20200826-221556.jpg)
I'm sorry for my crappy drawing skills and complete lack of understanding circuits. Now all I want is just to be able to supply the high-frequency output directly without having the rectifiers at all. I do hope it's possible at all :,( All the coils only have 1 output so I don't have a clue how to connect them up

I think together with the pics I posted yesterday this paints a pretty clear picture of how it works. Now for me to understand it.. that's another thing as I've tried haha. Explains why I'm a chemist and not an electrician/physicist lol
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 26, 2020, 09:59:43 PM
by golly
you will be the late Nielsquake if you start holding wires like that
one moments inattention and pick up the wrong wire and it will fatally bite you when the insulation punctures through

BE CAREFUL

Yep, noted and done! already using a chicken stick atm. I had myself isolated on a plastic chair so I was thinking about safety a little but it's better to be extra safe than sorry.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 27, 2020, 04:59:39 PM
Okay so I couldn't live with the fact I posted that crappy drawn circuit diagram so I spend an hour looking at the thing and meticulously mapping the wires and I think I was able to draw the full circuit now.

(https://i.imgur.com/yuzpPLr.jpg)
(https://i.imgur.com/lFLig7t.jpg)


I hope this makes it easier to understand. It seems there are 2 full transformers on this single core that seem to have the bifillar primary coils in opposing directions. Now the winding direction of the secondary coils is a mystery to me and how to wire them up for AC output even more. Would it be possible to wire these 2 transformers together in series and drive them from both inputs at once for AC output? I think it's starting to make a bit more sense to me now how this thing works so that's good I suppose but I could be completely wrong...
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: klugesmith on August 27, 2020, 08:23:35 PM
It's not uncommon to have isolated secondary windings, individually rectified & then wired in series, as an alternative to voltage multiplication.
My high frequency Bennett XRT tanks each have about 6 secondaries contributing 1/6 of the 62.5 kV output voltage (per tank).

Here's a schematic I found for a previously-purchased XRT that never did me any good.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: Teravolt on August 27, 2020, 09:36:33 PM
it looks like you have 8 seconaries. each two have there own bridge rectifier. I assume that each winding is floating. if this is the case each set of secondaries and bridge should be treated as though they are a battery so you can set them in parallel or series them. if you series them the potensial will be the highest`and the hazard for arcing to other things like metal or you will go up. you won't be able to hold that yellow wire any more.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 27, 2020, 11:30:35 PM
it looks like you have 8 seconaries. each two have there own bridge rectifier. I assume that each winding is floating. if this is the case each set of secondaries and bridge should be treated as though they are a battery so you can set them in parallel or series them. if you series them the potential will be the highest`and the hazard for arcing to other things like metal or you will go up. you won't be able to hold that yellow wire any more.

So when you say I can interpret the set of secondaries and the bridge rectifier as a battery, does that mean that for this transformer to be able to output anything in series requires the rectifiers? I wanted to try and make a housing that holds only the transformer under oil so I can use it with AC output and externally connect rectifiers if I needed a DC output. I kind of really want to see what it would look like to power a plasma globe with the output of this thing running on the mains but that would need me to be able to connect the secondaries up in a way that allows me to get an AC output. I want to know if the oscillations in the magnetic flux are equal throughout the whole transformer core so that all the outputs can be connected and remain in phase with each other. I know that connecting the DC outputs would work but in the end I think the rectifiers are a bit too large to be able to find a good housing for it that can hold a vacuum and I really do like the idea of it being as small as possible and as versatile as possible.
I imagine that all the coils that have the output from the secondaries on the left are wound clockwise and all that output on the right are wound counterclockwise, would this mean that connecting all the outputs of one side together and the other side together would create an AC potential between the 2 sides or would any lag in the magnetic conversion due to their spacial separation cause problems in the output.


Also I've noticed that both the wires that I used to get an output from the transformer go into one side of it only. One of the wires runs through the middle of the primary coil and then connects to the end of it to complete the circuit. This leads me to believe that I was only running one side of the transformer and not the whole thing. The enclosure this transformer was sitting in originally had 4 separate HV output terminals (the standard federal xray wire connection things) and I think it was made to be able to work with 2 tubes. Now I think this maybe has something to do with fancy xray machines that want to have the longest possible work time so they use 2 tubes and rather than making an expensive system that can switch the HV output between the tubes that most likely would require a lot of moving parts, they just put 2 full transformers on the coil to be able to use them interchangeably and allow for the other tube to cool down. This way the switching could easliy be done with software and no moving parts. The primary coils are wounded in 2 different directions so that must mean that they can't be used together right? Wouldn't the magnetic fields cancel out like that and generate heat or some physycsy shit like that. There seems to be no connections at all in the middle of the coil so I think it's not 8 secondaries connected but 2x4 making it 2 sepperate transformers that can't run at the same time. I guess that's still handy for if I mess up and burn the windings.
Soooo, you you think it is possible to apply the battery idea to the unrectified secondary coils connecting the sides and using the potential between them like I described? Would suck if AC is not possible.
also, what do you think about my idea of the 2 separate transformers, took me a lot of thinking about this but that is the only conclusion I can get to honestly.

According to someone selling these exact HV tanks there are some physical switching components that keep the voltage from going into the other output and I don't think that if you only power one side of the transformer the secondaries from the other side would not create any potential difference but then again, I'm only describing things as I see them and I have no idea what I'm even talking about honestly.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 27, 2020, 11:35:36 PM
It's not uncommon to have isolated secondary windings, individually rectified & then wired in series, as an alternative to voltage multiplication.
My high frequency Bennett XRT tanks each have about 6 secondaries contributing 1/6 of the 62.5 kV output voltage (per tank).

Here's a schematic I found for a previously-purchased XRT that never did me any good.


Very interesting schematic, nice knowing this is not an uncommon thing and to know what purpose it serves
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: nielsquake on August 28, 2020, 02:13:33 AM
what is your supply voltage beacaus you have a lot of current but not very much voltage, maybe 5KV -10Kv. if that is a x-ray transformer it is capible of an arc 3x bigger or more. maby a igbt brick half bridge setup running off the mains will get you there
Oh BTW, if you look at some of the older vids I posted in this thread you can see the 3mm spark gap that prevents the spark from crossing, it only connects through the ionized plasma when I touch the 2 electrodes but when I disconnect the spark gap the capacitors would charge and arc at the 150kv rated voltage the transformer is capable off but this seemed to blow up my ZVS drivers. I think the actual voltage was around the 50kv mark judging from the length of the sparks I could get before blowing my mosfets but I guess that is no accurate representation of the actual generated voltage due to the capacitors.
Title: Re: Is my xray transformer a ferrite core and how would I drive it?
Post by: HighVoltageRulezz on September 04, 2020, 05:33:13 PM
A quick word about safety:

I always take care the housing of my Xray tank is properly grounded and then I use the original HV wires- they have an outer (grounded) shield.. So if the insulation should arc through current will flow to ground and not to anything else...
One thing you might want to keep in mind with these cables though- when you have several meters the capacity of them is high enough to give you a nasty shock   ;D

Take care- these voltages with the currents you can easily achieve are no joke- they can kill you from a distance..
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