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Re: NST question 30ma or 60ma not sure?
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: NST question 30ma or 60ma not sure?
> Date: Thursday, February 10, 2000 1:44 AM
>
> Original Poster: Max Erhard <max.erhard-at-softhome-dot-net>
>
> Couldn't you measure the open circuit primary current too and take it
> away from the shorted current, in order to exclude any losses ?
>
>
Open circuit primary current is quite high (due to the inductance) even
though the power is low. If you measured the "in phase" component of the
current, it would only measure the iron losses and the IR losses in the
primary, but with no load on the secondary, and hence, no current flowing
in it, you wouldn't pick up the IR losses in the secondary.
Measuring all the transformer parameters is actually fairly easy, but you
DO need a wattmeter of some sort (I use an ancient surplus watthour meter
that has a 5Amp current winding and a 110V potential winding) to resolve
the Watts vs Vars issue. I have described in some detail on
http://home.earthlink-dot-net/~jimlux/hv/xfmrmeas.htm (which now that I look at
it, I should revise)
Another way is to put a series resistor in the circuit and use some
algebra. A bit trickier.
http://home.earthlink-dot-net/~jimlux/hv/varvom.htm