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Re: [TCML] MOT Resonace Reviled



Hi Jim,

Jim Mora wrote:
Hello Mot-man and all,
Oh Lord, don't say Mot-man (Finn? <big grin>). I am certainly not the Mot-man. I am simply performing a series of measurements and reacting to those measurements as I interpret them, nothing more. The MOT thread is ongoing and I would recommend making zero conclusions yet. The MOT case is sort of extreme in all these measurements and far more than say shunted NST's. It's simply one of those extreme transformers that tells some things about itself. The fact is, we use it for various reasons, and thus, we have the opportunity to look at it a little closer. That's really all that is going on from my part here.

Horray! Can we review the way to calculate or measure the output inductance
w and w/o the shunts and therefore the resonant capacitor(s)? I have (2)
2.2kv/1000kva MOT's in series- primary and secondary (240v in, 4400 out).
The cores are connected and floating. This to drop in an ammo can. I have
(2) Maxwell 2uf/15kv caps. The ammo can will hold one; but I suspect 2 will need to be paralleled for near 4uf from what I have gleaned so far. Maybe I
can squeeze some MOT caps in series in there for tuning. This I don't
presently have.
To perform the calculation, the measurements don't change (shunted or not, so that make it easy).
You might be able to squeeze some caps inside the ammo can, but I couldn't.
Nothing wrong with the caps outside the MOT pack.

The transformers will feed a bridge diode network, so I suppose the cores
need to stay floating? I do want the 4400+ DC out. Resonance seems to really
make a difference in Vout and allows for getting under the wire for Vin
saturation.
Resonance is always good for increased current, but you must maintain sensibility with secondary insulation. I would not attempt going over double the MOT output if looking at resonant charging using MOT transformers.


Should I disconnect the inner windings from the core and connect the inner
windings and ground the cores or leave them floating? They will of course be under oil and are very well mechanically isolated from the can on a dual .5"
phenolic plates which fits the footprint of the inside of the can. I am
patently not a MOT guy, but love how cheap they are for a lot of silicon
iron and copper!
My opinion is to float the cores so that the potential across each MOT is normal for the health of individual MOT's used. But I have not built a large MOT stack, so others are far more reliable for that type of information. But with a simple dual MOT where resonant charging is designed in, I would certainly float the cores. Think of 2 MOT's in series as 4 MOT's in series in that situation and it becomes apparent why floating the cores is needed.


This is a back burner project; though, the discussion is current. The
geometry looks like it was made for the ammo box as it sits on top. Where is
the best place to get MOT caps cheap without dumpster diving which is
forbidden here. It all belongs to the recycler who picks up the curbside
castaways in their bins or by arrangement. They deal only with big salvage
operations in LA.
Not sure. All my MOT's and caps come from dead ovens. Where I live, twice a year people can call up and leave a pile of crap in front of their house for pickup. If timed right, it's only out there for a 1 or 2 days. This is where I find MOT's. I simply stop, throw the oven in the car, and continue on. Last year when I put a load of junk out at the side walk, the next morning when I woke up for work (and early), half the junk was gone.

Take care,
Bart

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