Stephan,
It sounds like you are saturating the core at only 10 amps of DC control
voltage. The 12 amps of 400 volts may be the limit that you can push
through they system.
What is the cross sectional area of the core that you are using? There is
an approximate formula that will tell you how many KVA you can push
through a core based on its cross sectional area.
Dave
On 8/18/2010 1:07 PM, Teslalabor wrote:
Hello,
after several months searching for a suitable transformer for
modification into a saturable reactor, I now have found a big 3-phase
welding transformer, which was in use on 3-phase 400V here in Germany.
For my big teslacoil, which runs on 2-phase 400V, I want to modificate
this transformer into a magnetic amplifier. The goal is, to control the
current through the outer legs of the transformer @ 400V from 0-60
Amperes whith a DC current of 20A on the middle leg of the transformer.
Today I removed the heavy welding windings, and put the two outer legs of
the transformer in series and connected them on 400V. On the middle core
leg of the transformer, I wound a winding of several turns and applied 20
Amperes DC to it. I measured the 400V - current trough the outer
windings, and it arrised from 0,5A to 10A, when I regulated the DC from
0 - 20A.
There was something strange to me: The current in the 400V windings
firstly raised very fast when I raised the DC and then only very
smoothly.
I then doubled the windings on the DC winding. I got the 10A in the 400V
windings at only 10A (instead of 20A before) but it only increased to 12A
when I pulled the DC to 20A. In the same way: firstly very rapid current
rising, than only 2A from 10A to 20A DC. Why this? How many thousend
turns do I need for reaching 60Amps in the outer 400V windings? Is it
even possible?
Best Regards
Stefan
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