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Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
I have made several mot power supplies over time but this is quite different. Now i think i have reached pole pig territory what comes to power handling capacity and sec. voltage. There are total of 14 MOTs wired in series-parallel (7 MOTs in series and 2 rows in parallel). Total output voltage is roughly over 15.1kV and current.. enough? Everything is kept cool and well insulated under transformer oil. All secondaries are disconnected from core and most outer MOTs are equipped with factory made floating secondary with plenty of space between core and windings to be filled with oil.
All transformers are from old microwave ovens, rated at 1.44 - 1.5kVA @ 2100VAC-2300VAC each. Both rows are made from identical MOTs. It was a hell of a job to tear open microwave ovens and find matching pairs of large mots. I had to go through literally over 100 ovens to get what i needed.
Here is countainer i just welded together and ready to be painted:
This is welded together from 3mm steel plates. Reason for such heavy duty tank is that i really dont want more accidents with oil. I had my first oil cooled stack in large plastic countainer and when my dad was cleaning the workshop he punctured the countainer when moving stuff around. And it leaked empty almost inmediately. It was pretty though job to clean +50litres oil from floor
Now i need to make rig that holds all mots securely inside that countainer. Idea is that if(when) it needs repair, all guts can be lifted out in one piece with engine lift. I will allso make nice plexi glass lid and lathe HV bushings from white nylon or POM
One of those floating secondary MOTs i have. It survives easily over 10kV between prim and sec under oil. (tested with NST)
Registered Member #205
Joined: Sat Feb 18 2006, 11:59AM
Location: Skørping, Denmark
Posts: 741
Kizmo,
Nice work. I wonder why you have an uneven no. of transformers in series. Are they all stacked up from the same ground? If so, and it works, really high voltages can be generated by those Moulinex oven transformers. Since voltage breakdown is the issue, the best layout is centertapped, so that only half of the total voltage appears btwn windings.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
I forget to mention that it is center tapped wiring just like other MOT stacks. I could have added 2 extra mots to make it more symmetrical BUT it would raise sec. voltage too high for my needs (SGTC)
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Kizmo wrote ...
Nice stack, some questions 1) where do you get such a sh!tload of MO's? 2) I don't see how did you modify the MOT, could you explain? Edit: Sorry I see you didn't modify it, but anyway I think 10kV is a bit risky...
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New mot stack
