# A more efficient transformer

• p75213
In summary, the conversation discusses the idea of using a mag-amp construction in transformers to eliminate back EMF from the secondary to the primary, which would reduce the amperage draw from the source. However, this idea is not feasible as it goes against the principles of transformer efficiency and would essentially create free energy, which is not possible. There are existing winding configurations that are similar, but they are not efficient. The conversation also touches on different types of losses in transformers, such as copper loss, eddy currents, hysteresis, stray loss, mechanical loss, and magnetostriction.

#### p75213

I have been reading about mag-amps which gave me an idea for a more efficient transformer.
So the core is in the shape of a square or rectangle with a center piece dividing it into two. The construction of the outer core is larger (less reluctance) than the middle leg (greater reluctance). The primary coil is wound on the center piece and the secondaries on the outer sides. The flux from the secondaries would tend to be confined to the outer periphery of the core with very little entering the center core (would it cancel?). In the same way that this method of construction eliminates the high voltage induced in the control winding of a mag-amp so to would it eliminate the back emf from the secondaries to the primary. So the primary would only have to supply the magnetizing current.

It would be nice to see a drawing.

Please consider that 'primary' and 'secondary' are about a technical approach: by physics a transformer is supposed to work both ways.

Rive said:
It would be nice to see a drawing.

Please consider that 'primary' and 'secondary' are about a technical approach: by physics a transformer is supposed to work both ways.

Well think of a capital 'E' turned on its side with a connecting piece across the top. The primary coil is wound on the center leg and the secondaries wound on the two end legs. This transformer would only work one way.

p75213 said:
Well think of a capital 'E' turned on its side with a connecting piece across the top. The primary coil is wound on the center leg and the secondaries wound on the two end legs.
That's usually called EI core.

p75213 said:
This transformer would only work one way.
That's like getting a negative weight for a car after doing the math for the homework: you can be sure that you missed something.

Consider this: the starting point for transformer efficiency is that the more magnetic flux created by one of the coils goes through the other coil, the better. And there is no 'primary' or 'secondary' in this...

Rive said:
That's usually called EI core.

That's like getting a negative weight for a car after doing the math for the homework: you can be sure that you missed something.

Consider this: the starting point for transformer efficiency is that the more magnetic flux created by one of the coils goes through the other coil, the better. And there is no 'primary' or 'secondary' in this...

Surely if you only have to maintain the magnetizing current that creates the magnetic flux that has to be efficient.

Copper loss
Eddy currents
Hysteresis
Stray loss
Mechanical loss and magnetostriction

I’m not the one to answer your question, but transformers are generally highly efficient anyway. Which of the above would your design reduce? Stray loss? You are chipping away at a very small piece of inefficiency, and a small part of that, too. Interesting, though.

berkeman and russ_watters
p75213 said:
the secondaries wound on the two end legs.
Problem: not all the flux from the primary would pass through one of the secondaries. That means the coupling between primary and each secondary would be really poor. Magnetic circuits are a bit like electrical circuits and an alternative path for the magnetic flux is a bit like a leakage path across a battery terminals. The battery power would be wasted.

I have done a bit of reading on saturable core reactors in the past. Do a little research, you will find winding configurations similar to what you describe already exist.

Guineafowl said:
Copper loss
Eddy currents
Hysteresis
Stray loss
Mechanical loss and magnetostriction

I’m not the one to answer your question, but transformers are generally highly efficient anyway. Which of the above would your design reduce? Stray loss? You are chipping away at a very small piece of inefficiency, and a small part of that, too. Interesting, though.
None of the above. The idea is to remove the back emf from the secondary to the primary. The result of doing this is to reduce, if not cancel, the increase in amperage draw from the source due to the load on the secondary. Effectively the source only has to supply enough current to maintain the magnetic field in the primary (magnetizing current), no matter the load on the secondary.

p75213 said:
Effectively the source only has to supply enough current to maintain the magnetic field in the primary (magnetizing current), no matter the load on the secondary.
That sounds too much like getting energy from nowhere, which doesn't happen too often.

CalcNerd, russ_watters and berkeman
Averagesupernova said:
I have done a bit of reading on saturable core reactors in the past. Do a little research, you will find winding configurations similar to what you describe already exist.
Are they efficient though? Which was the initial question.

p75213 said:
None of the above. The idea is to remove the back emf from the secondary to the primary. The result of doing this is to reduce, if not cancel, the increase in amperage draw from the source due to the load on the secondary. Effectively the source only has to supply enough current to maintain the magnetic field in the primary (magnetizing current), no matter the load on the secondary.
Oh dear, I just saw this. I guess I need to go back and read the whole thread. Wait one...

UPDATE -- Thread closed for Moderation...

p75213 said:
The idea is to remove the back emf from the secondary to the primary. The result of doing this is to reduce, if not cancel, the increase in amperage draw from the source due to the load on the secondary.
What you are proposing and pursuing is Free Energy, and we don't waste folks time discussing such things here. In this case, it is enveloped in electronics fundamentals, but it is the same as if you were proposing a perpetual motion machine (PMM) waterwheel.

The back EMF is part of the normal transformer action that transfers energy from the source to the load. To try to eliminate the back EMF is basically the same as trying to create Free Energy.

I learned about PMMs and Free Energy when I was about 12 years old, when I drew up plans for a jet backpack and showed them to my father. I had an intake turbine coupled to an output turbine -- the intake turbine generated thrust, and the output turbine recovered the energy to supply back to the input turbine. My dad patiently explained PMMs and Free Energy to me then, and I was able to understand why such things are not possible.

And we provide links in the PF rules to help folks figure this stuff out without wasting forum electrons on such discussions:

Forbidden Topics said:
Pseudoscience, such as (but not limited to):
Perpetual motion and "free energy" discussions
http://en.wikipedia.org/wiki/Perpetual_motion
http://www.skepdic.com/freeenergy.html
http://www.skepdic.com/perpetual.html

Thread will remain closed.

CalcNerd and davenn