70 kV / 65 kW XRAY System, Transformer and Inverter - Isolation, Day 12

I give an overview of a 65kW X-ray generator system for a 70 kV X-ray transformer. The fullbridge of 400A 1200V IGBT bricks makes for a powerful inverter to drive the ferrite cored high voltage transformer.
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#electronicscreators

[@KaizerPowerElectronicsDk]

I completely forgot to add the introduction with date and a little story about the state of Denmark. The lockdown has been extended to last until April 13, 2020 now. So another 20 days of working from home/isolation.

[@manz5945]

Here in italy we have more than 60.000 cases of covid 19.... I think the lockdown is gonna last at least a few months....

[@KaizerPowerElectronicsDk]

Very grim in Italy, I hope you soon see the top and can heal.

[@SeanBZA]

Here in South Africa till 16 April, so we will see.

[@markhodgson2348]

Kaizer I love you ,and have been used to this feeling since 1914

[@SeanBZA]

Funny enough replacing an Arcotrol capacitor at work, that popped it's guts. Made week 6 of 1979, and finally died and extruded itself with a big puff of smoke. Yes PCB oil very likely, made before the ban, and no warning label on the case saying PCB free. So was wearing gloves during the clean up of the area where it went out, and made a nice big bag of contaminated paper wipes and solvent that went for disposal. New one is solid and plastic case, instead of oil filled aluminium, might not do 40 years of service, but 450VAC rated instead of 400VAC, so we will see. Machine still smells of cooked microwave popcorn.

[@KaizerPowerElectronicsDk]

Film capacitors can take some much higher voltage transients than the old oil/paper could. If you treat the film capacitor nice and keep its temperature below 50 (even better if lower, but never go near 70!) degree Celsius, then it would possibly outlive you :)

[@SeanBZA]

@@KaizerPowerElectronicsDk I find that the new capacitors are somewhat less robust. Old PCB filled 250VAC units I have, which are removed from equipment from the mid 1970's, withstand 1kV insulation test without any breakdown, while a more modern dry film type will typically start to break down and self heal within 2 years of use at the same test voltage. yes they do run in hot ambient in airconditioners, but the old ones sat next to the compressor with no cooling airflow, while the new ones are cooled by the fan. They just do not make the capacitors with such a reserve margin any more, and do not solder the cases shut, along with soldered in glass seals, it is too expensive. So instead dry resin impregnated, or crimped seals and coconut oil fill instead.

[@VermaV]

Very interesting video, thanks 🙂. I would like to know more about it like frequency, tank circuit, feedback etc.

[@zilipoper]

Hello Kaizer, are you just taking these X-ray machines apart? You can make them with this laboratory high-voltage power supply of 150 kilovolts. did you find this x-ray at the metal reception?

[@KaizerPowerElectronicsDk]

Hi zilipoper! Great to hear from a legend :) I got the best parts saved, two SKM400 inverters and a single HF 70kV tank. It is from scrap yard.

[@maxwellahiagbede1882]

Please, can help me fix problem on Philips MRS generator converter AV System

[@douro20]

Most Siemens X-ray equipment is made at the former Elema plant in Solna, Stockholm.

[@KaizerPowerElectronicsDk]

I was mistaken, this comes from Philips Optimus 65 :)

[@r3tr0nic]

Very nice bit of kit there, still hoping to someday get my paws on a set of my own. I can find them, just postage is never an option

[@KaizerPowerElectronicsDk]

Yesterday I secured myself a lot of 3 x-ray image plate scanners, a old x-ray power supply system and various peripherals to it all. Will make for some good future videos :) Where are you located? Even though that shipping above 20 kg is a killer almost anywhere in the world.

[@r3tr0nic]

@@KaizerPowerElectronicsDk That will indeed make for a nice vid *^^* For now and an unknown amount of time, the USA... I am sadly not on either coast (where concentrations of great finds seem to be...). Some of these items are so heavy that even domestic postage is by truck and expensive. I think most postal systems 20kg is the limit. At least, AusPost was (whom I had used most in past). I just have to get lucky to be in the right place and time. I can do the truck freight, it just is a hassle though dealing with, esp if it is international. Always had been something or another in the way. Funds, work, space, distance. I really do not have space now actually. Someday, I will have space, and place, and all that :) Hoping to be in NZ actually, but no clue how things will go as of this time

[@danielmeza3634]

Very interesting teardown. I remember when I had chance to service these type of equipment but I couldn’t see the rectifiers inside the transformer enclosure. ¿Have you got the x-ray head?... greetings from Mexico

[@KaizerPowerElectronicsDk]

Look at my Teardown video play list. There is a full xray system teardown of control panel, inverter, head (with transformer in) and collimator.

[@danielmeza3634]

Kaizer Power Electronics Thank you, I found them and have been seeing you these days. They are very interesting

[@rockmonkfuture7926]

Cool Stuff...please recommend some youtube channels or websites where I can find more information about IGBT brick array Inverters...I'm more into Railcar HV Traction inverter drives ...for making UltraScale MassDriver in my backyard...lol

[@KaizerPowerElectronicsDk]

Can you see the recommended channels that I subscribed to on my channel? That is a good start for all power electronics. Maybe it is better to find forums and ask specific questions to your project. I also run www.highvoltageforum.net which could be an option.

[@dolu9273]

I have a problem with my x-ray with Inverter fault

[@diecksl]

I wonder what type of xray apparatus was driven by this monster? Standard medical xray machines use some mA at best, but 65 kW at 70 kV is somewhere in the range of 1 amp beam current if I am not mistaken?

[@KaizerPowerElectronicsDk]

It was from a Philips Optimus 65 system if I recall correctly. Standard human full body/full chest/thorax x-ray.

[@KaizerPowerElectronicsDk]

You mentioned that getting x-ray equipment was the unicorn of high voltage hobby. Yesterday I secured myself a lot of 3 x-ray image plate scanners, a old x-ray power supply system and various peripherals to it all. Will make for some good future videos :)

[@T2D.SteveArcs]

You've got this exact same inverter now Lejf 😂, I just popped back to this video because I posted a picture of an inverter I've got that's the same as these and Mads commented, I thought I had commented on this video when I watched it but seems not 🤔 I'm getting old 😅... Hey Mads👋 cool video (still) 😅😂

[@annaoaulinovna]

blue parts are power factor correction capacitors. its used because they use inductive load. all inductive load brings more energy price. pfc correction caps makes capacitive loads and enerygy bill decreases. its about energy company rules. can you show the details of high voltage dc link of the inverter? please

[@KaizerPowerElectronicsDk]

Reactive power is not used in billing for electricity. So there is only a requirement from the utility to have at least 0.9 power factor, bad power factor only affects the amount of power you can pull through a service. You need bigger cables with bad power factor, to counter for the higher transmission losses.

[@roelmagparangalan7682]

Hi can i ask a question what is the cause of display sometimes gone afer minute its back? thank very much.

[@scienceinnovativebrain]

At what frequency it is operating And igbt model no. I want to see its hv transformers

[@KaizerPowerElectronicsDk]

Properly works around 20 kHz and its using Semikron SKM400 IGBT bricks. Check out my other videos about transformers, I am pretty sure I showed it in another video.

[@benhurren9711]

What voltage is the DC bus in the driver?

[@KaizerPowerElectronicsDk]

565ishVDC. 3x400VAC rectified

[@gammaleader96]

Very interesting to see. Why does the HV connector have 3 pins if it has only one conductor or did I get this wrong? Are these connectors still used in modern equipment, they seem kind of oldschool to me. Oh and your german sounded very german this time, do you actually speak some german? Greetings, Michael

[@KaizerPowerElectronicsDk]

There are very few industry standard high voltage connectors. About the only HV connectors manufactured by multiple companies are the Tyco LGH series, and the so-called federal standard connectors, used in x-ray systems. I think it just uses 3 contact points to insure a good connection, even if one of them should fail, you still have two others to prevent arcing in the contact point. The federal standard connector was a early standard and as with many other x-ray/medical approved things, they do not change if they work and are approved, new approvals and tests costs a lot of money. I speak fluent German, we have to learn German in Denmark (form 4th grade to 10th, when I was in school) and I also had it for 2 more years in the gymnasium. I then worked for a German company for 3 years, some 6-7 years ago. Es ist nicht alles perfekt, aber Ich kann Deutsch schreiben og sprechen gut genuch für meistens Verstehen, nur Meine Grammar könnte besser sein ;) Ich hab meistens von Bayerische leute gelernt, so vielicht es ist Bayrisch und nicht Deutsch Ich sprechen kann. Servus! (no spellchecking used, did I do well?)

[@gammaleader96]

@@KaizerPowerElectronicsDk That's interesting, I guess especially HV connectors that are able to carry some power seem to be quite rare, as you said, now that I had a look. Most standard connectors are mor BNC sized. ;) That makes sense. Maybe the resistor in the receptacle you showed is to make sure that the connector makes contact with this pin first as kind of a "soft start" in the connection? You are propably right, I forgot, that all of this is medical equipment after all. I am always amused to see, how old a lot of medical devices are. (A lot of somewhat modern medical equipment runs on Z80 or 68000 CPUs.) However there is propably way less that could possibly go wrong that way. Oh interesting, I didn't know that. But atleast from a geographical point of view, it makes sense to lear german, I guess. Servus, wie du sagst, die Grammatik könnte stellenweise etwas besser sein aber definitv gut zu verstehen, Respekt. :) Viele Grüße, Michael

[@SeanBZA]

@@KaizerPowerElectronicsDk Am I correct that the high voltage supply also has to provide filament current, so having 2 HV leads is for the filament, and then the negative supply is applied to them, with a grounded anode block. Multiple connectors so you can have a well isolated feedback system to ensure the leads are connected both sides of the link for a safety interlock, and one not easily defeated by simply shorting the 3 terminals in each plug together. Thus a terminating resistor on one side, and then the drive side has a well insulated transformer (probably the filament one) driving a sense circuit that will send a fault signal if the total wiring resistance between the sense leads is out of spec. Seem to remember seeing those boards in the transformer blocks.

[@KaizerPowerElectronicsDk]

@@SeanBZA sounds like a possible setup, i guess would could find the answer in some manuals from Franks hospital service website. I only ever took a head with builtin power supply apart: kaizerpowerelectronics.dk/teardown/siemens-polyphos-30-x-ray-125kv-head-teardown-part-1-of-3/

[@stephenbedih1696]

Hi, my name is Stephen Bedih of medizine Technical Services a Bio-medical Engineering Co. in Ghana. Which supply, install and maintain medical equipment. We have one GE AMX II in our workshop for repairs and the problem is :- There's 'Prep' but there's NO. Exposure when the Exposure SW is pressed. Can you please some possible causes to get the problem solved.or send me the service manual? Thank You & Kind Regards, Steve.

[@KaizerPowerElectronicsDk]

Hi Steve. I am sorry that I can not help you with those. I only had the unit to take it apart. Did you look up Franks hospital service on Google? Kind regards Mads

[@T2D.SteveArcs]

Interestingly (to me at least) the one i have and the one Lejf has seem to be exactly the same yet were from 150kv 65kw Philips machines .. i guess 65kw is 65kw 😅😂

[@KaizerPowerElectronicsDk]

I guess the 150 kV system must be rated for half the current then. Why do I have two of these inverters? Was there really two in one system?

[@T2D.SteveArcs]

@@KaizerPowerElectronicsDk the transformer is rated for 65kw so yes it must be rated for half the current at the full voltage 👍

[@heinrichhein2605]

So it is a LCC converter?

[@heinrichhein2605]

Thanks for showing

[@KaizerPowerElectronicsDk]

It could be a LCC inverter, but I would have to open up the tank in order to find out. It could also just be a series resonant inverter without the internal C.

[@heinrichhein2605]

The C can be also formed just by the secondary capacitance that how i designed them once before, because for high voltage this parasitic capacitance is quite problematic, but maybe a phase shift could be possible i think but fir that you would need an inductor, hmmm

[@SeanBZA]

@@heinrichhein2605 You can do it in the tank just by using a shift in the secondary coil location over the primary, and arranging the air gap and shunt pole pieces to give the extra inductor. Just like a microwave transformer, using leakage inductance to advantage. Saw that in an old ferroresonant converter that failed (spectacularly) which was unusual in that it only had a single very large multisection transformer, that had both the input winding, the ferroresonant winding for float charging the battery and for driving the output, and a second ferroresonant tank circuit, them a secondary winding. All sorts of shunt pole pieces between the windings, and a load of air gaps in the central core piece, just held together by the outer plates and a lot of varnished in bakelite spacers. Control board went bad, and as the output stage was made from nearly a whole tray of 2N3773's and a massive set of SCR blocks, and most of the TO3 cans had either a hole blown through them, or a missing emitter ( and of course a burnt out ballast resistor on each one) it was not economic to repair the board and replace all the silicon.

[@heinrichhein2605]

interesting, yes you can build the resonant Inductor with the leakage inductance, i really have to look at my transformer and do some measurement but for HV a llc would not make much sense i guess