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Author Topic: Transformer Induction  (Read 41581 times)
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There is an induced voltage that varies with position of the single probe as you described in your post #268.  There is a reasonable explanation for voltage being induced into the scope ground connection so it is different from the usual scope measurement.  A differential measurement of a voltage using two probes requires the common ground connection to be at an intermediate potential, usually half the value so that each one yields half the actual voltage.  How do you achieve that when the ground leads themselves have induced voltage?  For your differential measurement with two probes the system is much more complicated and your 2D schematic is not sufficient for an analysis.  Photos showing the layout in 3D would be better.  My inital reaction is that the potential of the common ground connection of the two probes is undetermined in relation to your post #268 results and will always result in a zero measurement.

Smudge

The connections to the outside wire with the differential probes was very similar to the pix of the probes measuring the 4 turn primary in my post #262.  With that test, it appears that the total voltage applied to the primary is divided between the vertical wires in the hole of the toroid!

I have to ask myself, since this also appears to be the conditions on the various secondary tests I have run, how is this possible?  I mean if the E-Field is a function of the A-Field and this field is thought to be circulating  the toroid in an azimuth direction, how is this possible.  Or, is there some other mechanism at work here?  This is the focus of my work at this time but I have to admit, I don't have a clue!!!

Pm

   

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The connections to the outside wire with the differential probes was very similar to the pix of the probes measuring the 4 turn primary in my post #262.  With that test, it appears that the total voltage applied to the primary is divided between the vertical wires in the hole of the toroid!

I have to ask myself, since this also appears to be the conditions on the various secondary tests I have run, how is this possible?  I mean if the E-Field is a function of the A-Field and this field is thought to be circulating  the toroid in an azimuth direction, how is this possible.
The E field coming from flux change in the core via E=-dA/dt where A lines form closed loops around that flux has a unique property.  An electrical circuit that encloses that core flux will have an induced voltage.  An electrical circuit that does not enclose that core flux will have zero induced voltage. If such a latter cicuit does produce a voltage there has to be an explanation and it appears from the work you have done the explanation is leakage flux that passes outside the core material.  So you have your probes and ground connections within a magnetic field that is changing with time. so your scope will give you the voltage induced into your circuit.  In some of your measurements it is a piece of wire shorting out your probe tip to the probe ground connection.  That will give you a voltage from the total leakage flux passing through that loop.  It is not the voltage that you think is across the piece of wire, it is from the flux passing through the loop.  You can vary the size of the loop and get varying voltage just by squeezing the ground connection so that it runs close to the probe or by altering their angle as you have discovered after Verpies' suggestion. 

Quote
Or, is there some other mechanism at work here?  This is the focus of my work at this time but I have to admit, I don't have a clue!!!
I think you are right to follow a new path but not by trying to measure the E field at different positions around the core flux using your oscilloscope.  Your suggestion to PhysicsProf that a cell placed in the core window will react to the E field there is good and that could be an indirect method for establishing what that field value is.  I think my suggestion that dielectric placed there will react can also provide an indirect measurement.

Smudge
   
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Smudge,

Thanks for your comments and suggestions.

Regards,
Pm
   

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so the efield, it is only present when there is a flux change?

mags
   
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so the efield, it is only present when there is a flux change?

mags

Yes.

Pm
   

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and that flux change, if it happens in thin air, is there an efield developed in the air?

mags
   

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and that flux change, if it happens in thin air, is there an efield developed in the air?
All free ions will me moved by this electric field.
   

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ok. so how do we measure that?  can we ionize a gas in a sealed glass tube, like neon?

mags
   
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The reason I started this thread is because I began to see (via experimentation) that perhaps transformer induction, as we now know it, was either incorrect of incomplete!  Let me try to explain.

Take the experiment in my post #262 which IMO is quite revealing!  Here we have a toroid (2) with a 4 turn primary and we apply 16v to this primary resulting in ~4v/turn using mosfet switching in a 3/4 bridge configuration.  A full bridge would be better but this is what I'm presently working with! 

So, we have a relatively low source impedance power supply and a primary winding with an inductance of ~260uH that yields the voltages in the table as shown.  My interpretation of this table is that the voltages measured across the portion of the primary wire that is between the upper and lower surfaces of the toroid, sum to nearly equal the total applied voltage to the primary.  I see no way that the differential probes taking these voltage measurements could or would have any effect on each wire segment's measurements! 

So, if this all true and correct, then consider the following- the instant we apply 16v to the primary winding, it will initially be evenly distributed around each turn of the primary.  As current then begins to flow thru the primary winding and continues to increase, flux will begin to flow in the core and also continue to increase.  Now here is my question- at what point in time and by what means, does the equally distributed voltage in the primary only appear in the primary wire that is between the upper and lower surfaces of the toroid?  This is the elephant in the room!

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Pm   
   

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ok. so how do we measure that?  can we ionize a gas in a sealed glass tube, like neon?
Definitely.  And when these charged particles slam into something with sufficient speed, they glow.

There are free ions in atmospheric air, too, but they don't live very long before they get neutralized.  These ions also get moved by such fields, but to get to decent speeds they need a strong field that can accelerate them meaningfully in the short time before they get neutralized.  Corona discharge makes more of them.  In partial-pressure systems the lifetime of these ions is much longer because the gas molecules are not packed together as densely as in the atmospheric air.
   

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...the instant we apply 16v to the primary winding, it will initially be evenly distributed around each turn of the primary.
No.  Read this.
   

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The reason I started this thread is because I began to see (via experimentation) that perhaps transformer induction, as we now know it, was either incorrect of incomplete!  Let me try to explain.

Take the experiment in my post #262 which IMO is quite revealing!  Here we have a toroid (2) with a 4 turn primary and we apply 16v to this primary resulting in ~4v/turn using mosfet switching in a 3/4 bridge configuration.  A full bridge would be better but this is what I'm presently working with! 

So, we have a relatively low source impedance power supply and a primary winding with an inductance of ~260uH that yields the voltages in the table as shown.  My interpretation of this table is that the voltages measured across the portion of the primary wire that is between the upper and lower surfaces of the toroid, sum to nearly equal the total applied voltage to the primary.  I see no way that the differential probes taking these voltage measurements could or would have any effect on each wire segment's measurements! 

So, if this all true and correct, then consider the following- the instant we apply 16v to the primary winding, it will initially be evenly distributed around each turn of the primary.  As current then begins to flow thru the primary winding and continues to increase, flux will begin to flow in the core and also continue to increase.  Now here is my question- at what point in time and by what means, does the equally distributed voltage in the primary only appear in the primary wire that is between the upper and lower surfaces of the toroid?  This is the elephant in the room!

Regards,
Pm   

ok. so i have a rotor on a motor, 1/4 in disk mags alternating n and s up and down on the outer face of the rotor.  give me a suggestion as to how i can do this to see. probably not just a simple neon bulb with the 2 electrodes because of the electrodes.

mags
   

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how can we detect the efield of a changing magnetic field without conductors being affected by the magnetic field???

OR, is it that it has to be a conductor that IS affected by the changing magnetic field presence, in order for that feield to show itself?????


mags
   
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ok. so i have a rotor on a motor, 1/4 in disk mags alternating n and s up and down on the outer face of the rotor.  give me a suggestion as to how i can do this to see. probably not just a simple neon bulb with the 2 electrodes because of the electrodes.

mags

Mags,

I wasn't responding to your question on ionization but rather pointing out my view on transformer induction.

Forgive me if I'm missing your point but I don't have an answer for your question above.

Regards,
Pm
   
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how can we detect the efield of a changing magnetic field without conductors being affected by the magnetic field???

OR, is it that it has to be a conductor that IS affected by the changing magnetic field presence, in order for that feield to show itself?????


mags

I think basically this is the question I'm asking.  If we were to take these same measurements on a straight solenoid coil, we would find the E-Field and the H-Field to be evenly distributed around the outside of the coil assembly.

Again, I hope I understand your questions!

Pm
   
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No.  Read this.

Yes, I agree with this paper.  With a careful single cycle measurement of the setup, I do not see evidence of the applied voltage being evenly distributed across the primary, so my assumption is incorrect!

Pm
   
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GREAT STUFF  Partsman.

It  is hard to see how the secondary loop is not complete.

I somewhat agree that differential measurement should deal with this .
Is there a difference between a tightly wrapped secondary and a very loosely wrapped one ?
   

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Mags,

I wasn't responding to your question on ionization but rather pointing out my view on transformer induction.

Forgive me if I'm missing your point but I don't have an answer for your question above.

Regards,
Pm

no problem.  let me put it this way...

if there is no conceivable way to detect, let alone use, the efield in the presence of a changing magnetic field unless there is a conductor present in that changing magnetic field, then i have to assume that it only appears in a conductor when that conductor is in the presence of a changing magnetic field....  sooo...

why is it so inconceivable that what you call an efield, isnt simply produced within the magnetically influenced, induced, conductor, and the magnetic field is the key to triggering that efield within the conductor?

ive asked for years and years for an example of how we can determine the presence of the 'efield' in the presence of a magnetic field, like in thin air.  in thin air or even say a vacuum, and never get a definitive answer.

i have my own theories of what is going on, but i dont think anyone has gotten what i suggested. so i leave it to you all to prove that there is an efield associated with a changing magnetic field at ALL TIMES, even in the absence of a conductor being influenced by that changing magnetic field..  makes no sense that the efield can only coexist with a magnetic field when that magnetic field is changing.

mags

« Last Edit: 2026-07-16, 06:53:30 by Magluvin »
   

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The electric field or changing magnetic field can be detected without a conductor because these fields accelerate free charges outside of conductors, too. For example like this:

  The effect of a moving magnetic field,
  on free charged particles.
   

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Like deflecting electrons in a television's CRT but that deflection has always been described as the yoke's 'magnetic field' causing the deflection. OR, in a CRT like an oscilloscope, the deflection is done by electrostatic charge of deflection plates.  It's one, or the other.  I've never seen it described that the yoke's changing magnetic field produces, or is accompanied by an e-Field to cause the deflection.

Thats a nice 'animation' you have there, but its not an example of what i can do on the bench to prove that a changing magnetic field is accompanied by an e-Field. In fact, if in the animation it were the particles that were moving and the magnet stationary, would the particles still deflect?? If the magnets field is no longer changing, well where is that e-Field now???  Same deflection, no changing magnetic field.

Now with all that said, in a TV's CRT with 'magnetic' deflection yokes, with no input to the yokes we get a bright dot in the middle of the screen because there is no deflection. Well what will happen to that bright dot in the middle of the screen if we apply some DC to one of the, say horizontal yokes?  Will the dot move from the center at first and then back to center because the dc input to that yolk is no longer changing???   or will it stay deflected?

If it stays deflected with DC applied to that yoke, and from what you guys describe that the e-Field is only present when the mag field is changing, then what is it that keeps the electron beam deflected if the e-Field is no longer present once the yoke's magnetic field is no longer changing?

mags

   

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I'm trying to stay on topic because of the claim of the e-Field here in the experiments. If it is way off or not related, we can move this to a new topic but if I'm correct, then what I have presented shows a large issue to the claims of the e-Field here and how and when it works, if it is even factual by description here.  In that case, things will have to be thought about differently when it comes to the theories in this thread, and should remain here.

mags
   

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I've never seen it described that the yoke's changing magnetic field produces, or is accompanied by an e-Field to cause the deflection.
Actually, television CRTs accelerate the electrons electrically (thus creating motion between the magnetic field, created by the deflection yoke, and the electrons) while the magnetic field deflects the moving electrons.  So both the electric and magnetic fields are at play in television CRTs.

... if in the animation it were the particles that were moving and the magnet stationary, would the particles still deflect??
Yes.  Only the relative motion matters for this effect ...and all motion is relative.

Will the dot move from the center at first and then back to center because the dc input to that yolk is no longer changing???   or will it stay deflected?
The dot will stay deflected.

What deflected it was the relative motion between the electron and the constant (not changing) magnetic field generated by the yoke.
It doesn't matter whether the electron is moving wrt the magnetic field or the magnetic field is moving wrt the electron.
Once the moving electron exits the magnetic field region, its path does not revert the previous angle but continues in a straight line (deflected).

Of course a moving magnetic field is a changing magnetic field ...and vice versa.

* wrt = with respect to
   
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GREAT STUFF  Partsman.

It  is hard to see how the secondary loop is not complete.

I somewhat agree that differential measurement should deal with this .
Is there a difference between a tightly wrapped secondary and a very loosely wrapped one ?

Thanks!  No, there appears to be no difference is how tight or loose the secondary is wound.

Pm
   

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Actually, television CRTs accelerate the electrons electrically (thus creating motion between the magnetic field, created by the deflection yoke, and the electrons) while the magnetic field deflects the moving electrons.  So both the electric and magnetic fields are at play in television CRTs.
Yes.  Only the relative motion matters for this effect ...and all motion is relative.
The dot will stay deflected.

What deflected it was the relative motion between the electron and the constant (not changing) magnetic field generated by the yoke.
It doesn't matter whether the electron is moving wrt the magnetic field or the magnetic field is moving wrt the electron.
Once the moving electron exits the magnetic field region, its path does not revert the previous angle but continues in a straight line (deflected).

Of course a moving magnetic field is a changing magnetic field ...and vice versa.

* wrt = with respect to

ok.  but im talking about the efield specifically and its definition of it only being there when the magnetic field is changing.  not sure why, but im feeling im either being misunderstood, or replies to my question are ignoring the core of the question.

ok. ill make it simple one more time..

1.  is there an efield associated with a non changing, non moving magnetic field?
2.  if not, then why?
3.  when a magnetic field does move or change, why does this efield as described and use of its term in this thread and many others, happen to 'appear' and exist when that magnetic field moves or changes??
4.  and finally, does this efield only present itself when a wire or any conductor is present in the changing magnetic field??


i see that it is used in theory as to calculating 'voltage' per turn when considering self induction and mutual induction, but i find that nobody really wants to answer the questions or claim that they dont understand the questions. my questions ar not that complicated.

mags

   

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"What deflected it was the relative motion between the electron and the constant (not changing) magnetic field generated by the yoke.
It doesn't matter whether the electron is moving wrt the magnetic field or the magnetic field is moving wrt the electron.
Once the moving electron exits the magnetic field region, its path does not revert the previous angle but continues in a straight line (deflected)."

ok. so the deflection is due to a relationship between the 'magnetic' field and the 'electron', nothing more.  correct?

mags

   
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