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1000 VA 230 VAC 50 Hz - How Much Inrush Current?
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Kleinstein:
Part of the problem, why the toroidial transformers are effected so much is that they have very little effective air gap and a high remanance magnetization. So quite often the magentic field does not start at zero, but can be up to about half the saturation value. The remanent field helps when starting with one polarity and makes the other polarity worse. With a remanent field at 50% the start up at the voltage peak would be about as good or bad as starting at the better polarity with zero crossing. Starting at the voltage peak is good when the core starts demagnetized (e.g. about OK with an EI core).
Benta:

--- Quote from: Kleinstein on March 09, 2022, 07:25:35 pm ---So quite often the magentic field does not start at zero, but can be up to about half the saturation value.

--- End quote ---
Source?
Must be some Chinese pig-iron toroid.

dannybeckett:
Fascinating, I wasn't aware of remanent magnetization! Thanks for the knowledge. I wonder if it's easy to measure...
 
https://www.belfuse.com/resources/otherdocument/signaltransformer/other-ST-signal-transformer-transformer-basics.pdf

Some useful transformer basics in this doc ^
Benta:

--- Quote from: dannybeckett on March 09, 2022, 08:57:45 pm ---I wasn't aware of remanent magnetization! Thanks for the knowledge. I wonder if it's easy to measure...

--- End quote ---
Not easy. And it's not really significant if you buy quality transformers. Kleinstein's "50%" is wildly exaggerated. It might be 10% if you're unlucky.
Unless, as said, the core is Chinese pig-iron.

Nice document you've found.
jonpaul:
Hi very odd, we are using  up to 5 KVA isolation both EI and toroïdal never seen this.
Signal Transformers EI and Germany toroïdal

 inrush current may be from cores near saturated, check the BH curve, ask manufacturer exact specs, peak B, core area, materials.

Your putting a band-aid on a cancer....fixing a much deeper problem.

If it is junk from China, suggesting to  get a high quality EU or USA product.

Jon
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