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Old 16th April 2017, 08:29 PM   #1
naca5 is offline naca5  Belgium
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Default Mains power: how to create a neutral?

Hi
I've a strange main, 3x220v.
When I put a phase tester in the wall plug, both indicate phase.
Good or not, every toroid hums here...
I have read that a phase can be recreate by converting AC to DC (rectifier) and then back to AC (converter).
Sounds weird for the rookie I'am...

Any advice?
Thanks

Last edited by naca5; 17th April 2017 at 03:42 PM. Reason: typo
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Old 16th April 2017, 08:38 PM   #2
kevinkr is offline kevinkr  United States
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You have 3 phase AC apparently, common in some domestic installations in Germany and Belgium if not elsewhere. (I lived in a place in the 1970s in Brussels that had it, no problems with buzzing transformers, but toroids weren't a thing then.)

Not sure why you would want an AC regenerator, and not sure it would address your noisy toroids either. (I suppose if your mains were heavily clipped toroids might buzz and there it could help.)

Mechanically isolating the toroids might be more effective if the noise couples into the chassis.
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Old 16th April 2017, 08:41 PM   #3
naca5 is offline naca5  Belgium
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Already tried ;-) even smaller ones hum loudly. Even smps are noisy.
Are transformer 2 phases friendly? I doubt
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Old 16th April 2017, 08:46 PM   #4
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This is indeed strange. If your mains socket would be mistakenly wired as two phases you should measure 380VAC between them.
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Old 16th April 2017, 08:47 PM   #5
naca5 is offline naca5  Belgium
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I measure something between 210 and 230v
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Old 16th April 2017, 08:54 PM   #6
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Then if you have conventional 3-phase system you should measure around 220 VAC between any phase and neutral and 380VAC between any pair of phases. I suspect your neutral wire may have too high impedance and as the result high potential difference to protective earth. This can explain why your tester showing both wires as phase.
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Old 16th April 2017, 08:55 PM   #7
naca5 is offline naca5  Belgium
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And this impedance issue can be fixed ?
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Old 16th April 2017, 08:58 PM   #8
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I guess you need help from an expert on site to do the real diagnostics and fixing.
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Old 16th April 2017, 08:58 PM   #9
naca5 is offline naca5  Belgium
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Thanks, I will ask one.
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Old 16th April 2017, 09:06 PM   #10
Ketje is offline Ketje  Belgium
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Quote:
Originally Posted by OlegSh View Post
Then if you have conventional 3-phase system you should measure around 220 VAC between any phase and neutral and 380VAC between any pair of phases. I suspect your neutral wire may have too high impedance and as the result high potential difference to protective earth. This can explain why your tester showing both wires as phase.
For many years now the voltages are changed.We had 220V and the UK 240V ,then along came Euromadness, now everyboddy is supposed to get 230V.If it is comming in as a star there is 3x 230V in respect to a center conductor and 400V between fases.Can also come in triagle with 3x230V between fases and no centre.
Transformers from the US intended for 60Hz are no good here with 50Hz.They overheat and buzz.
Mona
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