Missunderstanding and misconceptions in transformers

[mbrownn]

Transformers and magnetic flux

A transformer is basically two coils, one usually powered with the second giving an output. It relies on magnetic flux interactions between the coils, and by adding a core we can increase coupling and efficiency. We know that during changes of current in the primary, the flux density in the core changes and this induces a current in the secondary, constant current results in no induced current in the secondary.

So assuming we are working with a constantly changing current in the primary and we have a good core material, we have a reasonable transformer. When we consider the secondary current. This current flows in the opposite direction to the primary and so produces a magnetic field that opposes that created by the primary.

If this is the case, how is it possible to get the high efficiency output of a transformer, the the currents in the secondary must oppose the magnetic field of the primary with its own magnetic field?

For me Both magnetic fields must coexist.

If we take a simple spool and wind two coils on it, then place an iron rod in the core, we have a simple transformer. We can measure the magnetic field to some extent by testing how much weight that core can hold when we apply a current. It is possible to see that when we draw a current from the secondary, the core will drop the weight it can hold to some extent. Possible proof of opposing currents cancelling magnetic fields, but if were the case surely the current in the secondary must drop too, but it does not. What am I missing here?

[Magnethos]

I'm not an expert, but I understand that electric field generates a magnetic field. That changing magnetic field in the primary induces electric field in the secondary and that electric field generates another magnetic field which opposes to the electric field in the primary.

So, when you connect a load it's generated a back magneto motive force that opposes to the original force that creates the energy. This phenomenon is called reflectance.

The dipole transforms quantum energy to electrical usable energy. This dipole (electric field) generates a magnetic field that goes from the source to the load. When the load is connected a reverse MMF goes from the load to the energy source, destroying it (killing the dipole).

It's something similar to this:

[mbrownn]

I'm not an expert, but I understand that electric field generates a magnetic field. That changing magnetic field in the primary induces electric field in the secondary and that electric field generates another magnetic field which opposes to the electric field in the primary.

So, when you connect a load it's generated a back magneto motive force that opposes to the original force that creates the energy. This phenomenon is called reflectance.

The dipole transforms quantum energy to electrical usable energy. This dipole (electric field) generates a magnetic field that goes from the source to the load. When the load is connected a reverse MMF goes from the load to the energy source, destroying it (killing the dipole).

It's something similar to this:

In theory, and in linear flow diagrams that works in our head, but this is happening simultaneously, the opposition would prevent current flow from building up.

using the car analogy, if we apply a force to the rear of the car, it will accelerate. If we apply a second force to the front of the car, at the same time, the acceleration will be reduced, prevented or reversed. Either way the peek velocity would be less. So with 100% at the rear and 80% at the front the resultant is 20% from the rear.

Applying this analogy to current in a transformer, if the output current is 80% of the input, the opposing field would result in a magnetic field of 80% of the input. This would imply that 20% of the magnetic field is generating 80% of the current of the input. Obviously this does not make sense.

Another thing to think about. If we have an input field of 100% and an output field of 80%, we have a total field of 180% (like bucking coils). If the fields are cancelling we have 20%. Either way we don’t get an 80% output current.

I don’t need a highly technical answer, but a basic understanding of how this happens.

[Magnethos]

In theory, and in linear flow diagrams that works in our head, but this is happening simultaneously, the opposition would prevent current flow from building up.

using the car analogy, if we apply a force to the rear of the car, it will accelerate. If we apply a second force to the front of the car, at the same time, the acceleration will be reduced, prevented or reversed. Either way the peek velocity would be less. So with 100% at the rear and 80% at the front the resultant is 20% from the rear.

Applying this analogy to current in a transformer, if the output current is 80% of the input, the opposing field would result in a magnetic field of 80% of the input. This would imply that 20% of the magnetic field is generating 80% of the current of the input. Obviously this does not make sense.

Another thing to think about. If we have an input field of 100% and an output field of 80%, we have a total field of 180% (like bucking coils). If the fields are cancelling we have 20%. Either way we don’t get an 80% output current.

I don’t need a highly technical answer, but a basic understanding of how this happens.

I don't have a technical knowledge about how happens, but I can explain something about how I think it happens.

You've made a good observation about 80% and 20%. Think about a magnet. A magnet is 50% south and 50% north.


50% of force in forward direction and 50% force in backward direction means a total of zero. Zero means no resultant force.

Space is maybe the same. 50% and 50%, which means zero, neutral. For that reason the particles are called Neutrinos (neutral).

About what you say is very interesting. Have you thought about that the opposite forces don't cancel each other because they've different phases? It could be an explanation. To cancel each other they have to flow in opposite directions and the same phase. When the phase is different they don't fully cancel each other.

[Magnethos]

Think about a slope and the 2 guys, one in the rear and other in the front.
To stop the car they've to perform difference forces in the rear and in the front.



Maybe in the transformer it's more easy to the current to travel in one direction and more difficult to travel in the other direction. That is similar to the slope example.
Current travels in the path of least resistance.

[citfta]

Hi guys,

Mbrownn you are slightly mistaken about how a transformer works. The secondary current does NOT oppose the primary current. Here is a simple test to prove that to yourself. Connect a transformer to an AC source with no load on the secondary. Using a clamp on ammeter or a regular ammeter measure the current going through the primary winding. Now put a load on the secondary and again check the primary winding current. You will see it has gone UP not down.

If I recall correctly the explanation for that effect is that without any secondary current flow the primary current creates such a strong magnetic field it saturates the core and that raises the impedance to the point that only enough current flows to maintain the saturation of the core. Then when a load is applied it reduces the magnetic field causing an increase in primary current to try and maintain the magnetic field.

All of that is from memory so you might want to check that on an electronics training site to make sure it is all correct.

Carroll

[mbrownn]

About what you say is very interesting. Have you thought about that the opposite forces don't cancel each other because they've different phases? It could be an explanation. To cancel each other they have to flow in opposite directions and the same phase. When the phase is different they don't fully cancel each other.

This is a possibility. In my basic transformer test I would say the magnetic force was reduced by about 20% although I have no means of measuring it accurately. There is obviously a lot more to this than is written about in the standard physics text books.

I consider electrical theory to be an oversimplified incomplete theory. No one seems to know anything about magnetism, at least not in the standard physics world. We do know there is a relationship between the two and that’s about it.

It does seem that we can have opposing magnetic fields created by coils that increase field power as in bucking coils, and reduce field power as in transformers, but the effects are not linear or as you would intuitively expect.

[mbrownn]

Think about a slope and the 2 guys, one in the rear and other in the front.
To stop the car they've to perform difference forces in the rear and in the front.



Maybe in the transformer it's more easy to the current to travel in one direction and more difficult to travel in the other direction. That is similar to the slope example.
Current travels in the path of least resistance.

Interesting Idea.

Mbrownn you are slightly mistaken about how a transformer works. The secondary current does NOT oppose the primary current. Here is a simple test to prove that to yourself. Connect a transformer to an AC source with no load on the secondary. Using a clamp on ammeter or a regular ammeter measure the current going through the primary winding. Now put a load on the secondary and again check the primary winding current. You will see it has gone UP not down.

Yes I understand this, the current in the secondary lowers the inductance of the primary.

If I recall correctly the explanation for that effect is that without any secondary current flow the primary current creates such a strong magnetic field it saturates the core and that raises the impedance to the point that only enough current flows to maintain the saturation of the core. Then when a load is applied it reduces the magnetic field causing an increase in primary current to try and maintain the magnetic field.

All of that is from memory so you might want to check that on an electronics training site to make sure it is all correct.

Carroll

This seems to make sense and so is possible, but still does not explain how we can get 80% current output and have the two opposing fields.

Thanks for the input guys

[Magnethos]

This is a possibility. In my basic transformer test I would say the magnetic force was reduced by about 20% although I have no means of measuring it accurately. There is obviously a lot more to this than is written about in the standard physics text books.

I consider electrical theory to be an oversimplified incomplete theory. No one seems to know anything about magnetism, at least not in the standard physics world. We do know there is a relationship between the two and that’s about it.

It does seem that we can have opposing magnetic fields created by coils that increase field power as in bucking coils, and reduce field power as in transformers, but the effects are not linear or as you would intuitively expect.

First of all everyone knows that science cannot explain everything. Maybe it could be because to explain everything it's needed an extended and a different approach to solve the questions.

About the effects in the real world, almost everything is non-linear. Of course.

I've heard about bucking coils, but I don't know anything about them.

[citfta]

Just the other day I was watching a video where someone had a magnet on the front of a CRT. You could clearly see the effect of the magnet on the screen. Then he put another magnet of opposite polarity on top of the first one. The effect on the screen was that the effect was greatly reduced which implies the second magnetic field was cancelling the first magnetic field. Since the first magnet was right against the screen it's effect was not totally cancelled but was greatly reduced.

So if in a transformer the current in the secondary creates a magnetic field that opposes the field from the primary then the effect would be it would weaken the field of the primary and thus allow more current to flow in the primary. Does that make sense now?

On an additional note. All this theory applies only if you are applying a normal sine wave AC input into the primary. If you want to see something interesting apply a very short pulse rapid DC input to the primary and see what effect that has on the kind of load you can run.

Carroll

[Magnethos]

Just the other day I was watching a video where someone had a magnet on the front of a CRT. You could clearly see the effect of the magnet on the screen. Then he put another magnet of opposite polarity on top of the first one. The effect on the screen was that the effect was greatly reduced which implies the second magnetic field was cancelling the first magnetic field. Since the first magnet was right against the screen it's effect was not totally cancelled but was greatly reduced.

So if in a transformer the current in the secondary creates a magnetic field that opposes the field from the primary then the effect would be it would weaken the field of the primary and thus allow more current to flow in the primary. Does that make sense now?

On an additional note. All this theory applies only if you are applying a normal sine wave AC input into the primary. If you want to see something interesting apply a very short pulse rapid DC input to the primary and see what effect that has on the kind of load you can run.

Carroll

Do you remember that Floyd Sweet made a modification in a TV and he was able to see "cycloids"?

I would like to know more about this because I have no idea what a cycloid is, what is the modification in the TV and what is the relation between cycloids and magnetism.

[citfta]

I don't know anything about Sweet's modification to a TV but here is a link to the definition of a cycloid:

https://en.wikipedia.org/wiki/Cycloid

Carroll

[mbrownn]

All this theory applies only if you are applying a normal sine wave AC input into the primary. If you want to see something interesting apply a very short pulse rapid DC input to the primary and see what effect that has on the kind of load you can run.

Carroll

If I can get a better understanding of the AC operation, that may help me with the pulsed DC operation which is something I am researching. Air gaps also have an effect. I’m at a bit of a standstill in my understanding, so I'm asking simple questions to try and find out if there is some basics that I'm not aware of. There is a lot of complex mathematical models, but they are so complex that I cant grasp it at this time. My tests and the models do not seem to be close, maybe because the models are based on conventional equipment operated in conventional ways, and my device is unconventional.

[Magnethos]

If I can get a better understanding of the AC operation, that may help me with the pulsed DC operation which is something I am researching. Air gaps also have an effect. I’m at a bit of a standstill in my understanding, so I'm asking simple questions to try and find out if there is some basics that I'm not aware of. There is a lot of complex mathematical models, but they are so complex that I cant grasp it at this time. My tests and the models do not seem to be close, maybe because the models are based on conventional equipment operated in conventional ways, and my device is unconventional.

I understand you. You want to know how to understand better your unconventional model. So you're trying to find anything that might help to you.

As you know, 99.99% of the models are based on conventional theories. So it won't be easy.

[mbrownn]

I understand you. You want to know how to understand better your unconventional model. So you're trying to find anything that might help to you.

As you know, 99.99% of the models are based on conventional theories. So it won't be easy.

Yes, Its like building a wall with bricks, we can all use Lego but what if the bricks were round, could you still do it?

With all things, if you cant understand, go back to basics and try again.

In my transformer I get reasonable performance, but If I understood how they actually work and not just how the model represents them, I could do better.

I suspect a part of the reason we cannot get an accurate understanding of the first model is that some of the interaction between the coils is direct and some is through the iron. Bifilar coils make excellent use of direct interaction.

The transformer described before was totally conventional. Now I will introduce the first variation Instead of using an iron rod I will use a U shaped piece of iron with a keeper, and instead of placing one coil on top of the other we have one coil on each leg.

Now the two coils have to interact through the iron and cannot interact directly between each other. With the addition of the keeper the efficiency rises somewhat but without it, the electrical performance is similar to before. The difference appears to be the magnetic pull of the core, it does not seem to be weakened as much by the current draw from the secondary. As I said, I don’t have accurate measuring equipment to test the pull but it does seem to perform better than when one coil is in top of the other. I'm only testing the pull on one leg. This would suggest to me that the interaction directly between two coils effects what is in the core.

This makes sense, but it exacerbates our original problem of the amount of magnetic field required to give our 80% current. Instead of 20% it may be 15 or even 10%. There must be something else going on here. The magnetic interaction going on between the two coils, has to be through the core. I believe the magnetic loss due to permeability in the core, and ohms law is the reason the current is only 80%. It seams to me that the flux from the primary coil has to reach the secondary via the core to work. If any flux was cancelled we would get a bigger drop in current in the secondary.

I had not thought of this before it was mentioned on this thread. The idea of the flux from the secondary being out of phase with the primary still seems possible and because of the physical change of location of the secondary that phase shift could be greater. What do you think?

Of course i could be completely wrong and barking up the wrong tree