Dont worry, you cannot adversely affect the core of an AVC if it is a nickel one by passing DC through the winding, unless of course the
DC current is sufficient to burn out the winding !
Naturally there will be some magnetism remaining in the core when the magnetising force is removed ie when the DC is removed . This property
is called remanance. an 80% nickel core will have a lower remanance than a 49% one but both are much lower than GOSS. Amorphous and
nano crystalline cores have even lower remanance. depending on how or if they are annealed.
The hysteresis plot of the core material will show you what the maximum remanance value is for a particular core material.
I measure the winding DCR of the ones I make all the time without problems.
DC current is sufficient to burn out the winding !
Naturally there will be some magnetism remaining in the core when the magnetising force is removed ie when the DC is removed . This property
is called remanance. an 80% nickel core will have a lower remanance than a 49% one but both are much lower than GOSS. Amorphous and
nano crystalline cores have even lower remanance. depending on how or if they are annealed.
The hysteresis plot of the core material will show you what the maximum remanance value is for a particular core material.
I measure the winding DCR of the ones I make all the time without problems.
Of course it can be reversed by demagnetizing the transformer (by means of an AC voltage sweep into saturation). It is however better to solve troubles by not letting them occur but that is very Dutch/German I guess.
Never connect a DMM in resistance mode to such transformers as they will not loose the magnetization by themselves. Why would you? Connecting DC to a transformer does not have any benefit, only drawbacks. If you have nothing to do and still wish to measure something then use small AC voltages from a signal generator instead of course starting with 0V.
Never connect a DMM in resistance mode to such transformers as they will not loose the magnetization by themselves. Why would you? Connecting DC to a transformer does not have any benefit, only drawbacks. If you have nothing to do and still wish to measure something then use small AC voltages from a signal generator instead of course starting with 0V.
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Not that I had nothing else to measure 
,
I was looking for a way to sort the positions—my avc‘s are from germany, but they lack documentation or clear/proper wire-colours.
So I got more homework: they‘re maybe/probably magnetized, how do I verify this, and find the cure (which you gave me a direction)
Woo-hoo bzzt.
,I was looking for a way to sort the positions—my avc‘s are from germany, but they lack documentation or clear/proper wire-colours.
So I got more homework: they‘re maybe/probably magnetized, how do I verify this, and find the cure (which you gave me a direction)
Woo-hoo bzzt.
The D.C. could leave a bit of magnetism residue in the core. Best way to fix that is to run some AC through the transformer to demagnetize it. Music signal could work for small signal transformers such as SUTs and microphone ones. When using a DVM to check for continuity, use the highest ohms range, since the meter sources its tiniest test current in its highest ranges.
From Germany without documentation means they are stolen
If so, then he must've got quite a bunch of them. I got two of them, "painted" black in a very clumsy way. yuck. But I got them.
Still, it hopefully will be the "Feels good" moment, once upon a time.