# Re: [TCML] Questions about saturable reactor / magnetic amplifier

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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