PermO

DC measurement is magnetizing core ?
« on: March 11, 2021, 08:48:31 AM »
Hello,

I know that DC voltage can permanently magnetise the core of a transformer.

But if I have an unknown (audio) transformer and I use a Fluke multimeter to measure the resistance to somehow figure what is what on the transformer...

Will this 'damage' the transformer ?

I ask this as someone mentioned I screwed up two transformers using my Fluke on the windings.
Does a multimeter for a few secs produce enough current to permanently magnetize a transformer core ?

Is this really so ?

"It's very important that you run trough the door, not trough the wall" - Sadhguru


EmRR

Re: DC measurement is magnetizing core ?
« Reply #1 on: March 11, 2021, 09:18:10 AM »
No.  Many manufacturers list DC resistances on schematics for that exact reason. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

abbey road d enfer

Re: DC measurement is magnetizing core ?
« Reply #2 on: March 11, 2021, 10:05:45 AM »
Hello,

I know that DC voltage can permanently magnetise the core of a transformer.
Current, not voltage.

Quote
Does a multimeter for a few secs produce enough current to permanently magnetize a transformer core ?
It would take a brute of a multimeter to do that.
Nothing can "permanently magnetize a transformer core". It's always possible (and easy) to demag.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

PermO

Re: DC measurement is magnetizing core ?
« Reply #3 on: March 11, 2021, 10:44:14 AM »
Thanks a lot for this !


Learned some again  ;)
"It's very important that you run trough the door, not trough the wall" - Sadhguru


 

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