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Re: MOT Primary Current Question

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
So, why does the MOT saturate with two in series since each only sees 60Vac. Also, why dont they saturate in a microwave oven (or if they do, why isn't this a problem)??? 

I like your noblow fuse - need to get it patented :o)))

Gerry R.



Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,
In the plasma ball test last night, we were running two MOTs in series to get the voltage up to 5400V charging a 60uF cap through 440k ohms "SLOW"... After a few minutes the "dumb" fuse blew :-p I forgot the thing even "had" a fuse... The cores were in far saturation and eating current like mad.... It was an 8 amp slow blow...
Fortunately, we were able to come up with the "proper" size replacement right away :o))) 

http://hot-streamer.com/temp/No-Blow_fuse.JPG
Unlike a penny, 1/4 inch copper tube fits just right ;-)))) There was even A mic to get it right at 1.25 inches long :o)) But core saturation in MOTs really limits them to like 90VAC devices... But played with right, they can do wonderful things!!! 

Cheers,

        Terry


At 06:53 PM 6/12/2006, you wrote:

As Terry replied, the MOT current will be just an amp or two until about 100
to 105 volts are applied to the primary.  Then the current will start
ramping up rapidly as the core saturates for more and more of each
half-cycle.  So the secret to using MOTs, is to figure out how many MOTs you
need in series for each half of your MOT stack (typically 1 to 3), then add
one more MOT in series with each half of the MOT stack and run the primaries
at 100 volts or less.  This gets you the voltage you need without the cores
reaching saturation.

The other not so secret help is to find MOTs that are big bruisers (big
cores).  The really old ovens used were designed more conservatively and had
much beefier MOTs in them.

My question, which I asked years ago and never got an answer, is this:
Suppose your MOT at 120 VAC applied draws 5 amps with no load.  Then suppose
a load is applied, and the total primary current goes up to 10 amps, for
example.  Does a load on the secondary have any effect on core saturation
for a constant primary voltage?  In other words, would less power be wasted
in the core so that more power ends up in the secondary supplying power to a
load?

Thanks,
--Steve


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, June 12, 2006 12:21 AM
Subject: MOT Primary Current Question


> Original poster: norman@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> I measured the primary current of a small 120 VAC MOT. To my surprise > the > primary current was 10 Amps with the secondary open! The MOT is about > 4" 
x 3"
> x 3" and came from a 1000 Watt oven.  Is the MOT bad, or do these
transformers
> just have a low primary inductance? The primary wire is aluminum and > the 
> secondary voltage was measured by me at about 1800 Volts.  Also, I also
> measured a much larger transformer from (I think) an older oven with a
copper
> primary and it drew 6 Amps. The small transformer was very beat up and > it 
is
> possible that there is a short in the primary.  If you guys out there
think
> that the primary must be shorted then I will rewind it, but if the
transformer
> is acting normally then rewinding it will not reduce the current.
>
>
>
>
>