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Re: [TCML] BPS Testing

Hi John,

I agree, if only 3 laminations then this makes only slight difference. I think the fact that the NST's get warm at 140Vac is showing that the transformers are likely saturating. But this of course would have to measured against a normal input voltage temperature. What is strange, is how saturation affects the current available for cap charging. This is the key. If we run our NST's into saturation for low duty cycles, it may be a big plus for getting a lot of current our of a little transformer which would increase bps.

I'll measure power this weekend when I run the bps testing. I'll check 120V and 140V power draw for the 15/60 Franceformers.

Take care,

FutureT@xxxxxxx wrote:
Bart, Gary, The core is about 2" thick with all the laminations. The laminations are 0.015" thick each. I left out
about 3 laminations, so that would be 0.045" missing out of  2",
which is about 2.25% of the thickness.  I  wouldn't
expect that to make much difference in the current draw,
and saturation even if the core is right on the edge of saturation,
but maybe it could.  Actually at 140VAC all NST's are in
saturation to some degree. In support of this view, I have another NST which is the robust 12/30 NST which I use on the TT-42 coil. I also depotted it
and left out a few laminations.  In this case I was using the
NST on the same coil both before and after the depotting, and
I didn't notice any change in performance or current draw after
the depotting.  The NST was robust (extra powerful) both  before
and after the depotting. There might have been a slight difference in current draw which was too difficult to measure using my meters. It's possible that some NST's might be affected differently
by small changes in the number of laminations or how well
the core pieces go back together.  I have no way of knowing
this for sure. My previous posting was mostly to suggest that Gary Lau's
15/60 Jefferson might not be the only Jefferson which draws a
lot of current since mine drew 25 amps.  It's possible the
depotting had some effect, but I don't have any information on the before and after behavior when used on the same TC
for that NST unfortunately.
Gary, when you depotted the NST, did you disassemble the
core and slide the straight core off of the laminated frame?
Or did you leave the core intact and just soak it to clean it?
Regarding 140VAC operation for NST's, this does tend to put them into saturation to some degree. This is true for pole pigs as well. Both of my depotted NST's run hot, but my un-depotted NST's run hot also at 140VAC in TC use. Cheers,

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