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Re: Measuring Current Output of MOT's?



Original poster: Sean Taylor <sstaylor-at-uiuc.edu> 


>My initial conclusion is that I'm either going about this all wrong, or 
>that most MOT's are capable of currents much higher than 300mA, at least 
>for short periods of time.

Kinda and yes - Don't bother with the resistors, just have a meter with a 
fast response time and short the output through the ammeter section your 
meter.  Have it insulated from ground, though a high voltage *shoudln't* 
appear across it unless one of the leads lets go (specifically the ground 
lead).  A better way would be to use a clamp on meter with the transformer 
lead shorted and a decent amount of insulation - just in case.

A few tips - 1) I said fast response cause chances are you're going to blow 
a breaker, 2) DON'T HOLD THE METER!!!! 3) The MOT will heat up, so don't do 
this too long, but run it at a full 120 in if that's how you're going to be 
running it on a TC (ie not 2 primaries in series).

The reason your resistor method didn't work is because the current output 
will be drastically different at 10V compared to 120V in, and at 300 mA, 
you're asking the resistors to dissipate almost 20W, and the MOT is capable 
of a lot more than 300 mA - usually over 1A if not ballasted in any way, 
and with 1A, the resistor will dissipate 190W each!!

Hope this helps, please play safe with MOTs, they can kill you pretty easily!

Sean Taylor
Urbana, IL