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Transformers

On Fri, 9 Feb 1996 I wrote:


>         I've got an Atlas Device Corporation 6500W Arc Lamp starter that I
 > have been trying to determine the output current on. It is a shunt limited
 > transformer with a core 6.25" long, 3.75" high and 1.25" X 1.25" cross
 > section. It's name plate rates it a 220v 50A, but the 50A MUST be a surge
 > rating, nothing inside is that heavy! With 110Vac applied to the primary I
 > measure 7.28Kv out. I find this reasonalble for a 220v transformer run on
 > 110v.
 >         Now for the confusing part. When I connect an ampeure meter to the
 > secondary I measure NO current! Even on the 250uA scale! When I use a load
 > resistor 1 ohm = 0uV. 250 ohm = 5v => 20ma, 2100 ohm = 43v => 20.5ma. Am I
 > missing some fact about shunt limited transformers? This transformer is
 > massive compared to the 30ma neons I've seen. Does halving the input
>voltage more than halve the output current? Does the load effect the output
>current?

Today, 96/02/10, I went an visited tom renko (tahoetom), whom is building
his first TC, I'll let him post his results. I saw a REAL 15Kv 60ma neon
transformer! My transformer is small in comparison! Based on physical size,
I would beleave the 20ma or 30ma that I measured. I think that I was mislead
by the small size of the (mislabled?) 30ma neon that I'd seen previously!

p.s.
 I did forget to figure in the 20 ohm primary resistance, at 110v that is
significant, when I was thinking about it. And this is the first time that
I've seen inductance with an ohm meter! When I connected the ohm meter to
the secondary, the meter took 3 seconds to settle to a final value! I didn't
beleave it, so I shorted the meter leads, bam, 0. I measured the secondary
again, slooooooooooooooooooooooooooooowly it settled to it's final value.

                NEAT!
                (i get excited over the  simplest things.)

                        jim