How does an electric motor convert electrical energy to mechanical energy?

[tor2006]

how does electric motor convert electrical energy to mechanical energy.
Hello
I do not understand the following electric power is P = V * I electric motors operate on the principle of repulsion and attraction of magnetism. What confuses me where that power ends because as far as I know, the electron current itself generates a magnetic field and how this energy actually ends ,the electrons except resistance from the conductor have no where to lose energy.
Law of energy conservation energy is converted from one to another but i can not understand that only one part of power is lost on resistance .friction,eddy current ,hysteresise ... where is other part of power the current is the current the electrons need to lose energy somewhere, and as far as I know except the electron movement, the other energies are not needed to create the magnetic field .

I would ask if someone can explain how this works because i do not understand thank you

 

[Dr.D]

You would do well to start by reading up on self and mutual inductance. Transformers use this to move energy from one winding to another, and motors perform similarly. In many respects, motors are a bit like transformers with movable components. This is the place I would suggest that you start. Beyond that, get an intro level electrical machines text, and call @jim hardy .

 

[tor2006]

You would do well to start by reading up on self and mutual inductance. Transformers use this to move energy from one winding to another, and motors perform similarly. In many respects, motors are a bit like transformers with movable components. This is the place I would suggest that you start. Beyond that, get an intro level electrical machines text, and call @jim hardy .

I know where I made a mistake the current generates a magnetic field if we do a useful work with that magnetic field we converted the energy .for electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .copper losses reduce the magnetic field and thus reduce useful work naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right to thank you.

 

[jim hardy]

What confuses me where that power ends because as far as I know, the electron current itself generates a magnetic field and how this energy actually ends ,the electrons except resistance from the conductor have no where to lose energy.

Do you know about the force exerted on a charge that's moving in a magnetic field ? Does "Right Hand Rule " ring a bell of familiarity ?
from http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

Imagine that wire is in the armature of a motor. Current through it causes it to experience a force that turns the rotor. Work is done when the wire is pushed by that force through a distance.

Since motor rotors tend to be cylinders with loops of wire, the force becomes a torque that's transmitted to the shaft

Look up torque on a coil that's carrying current in a magnetic field.
from http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html#c5

Power is torque X RPM X a constant that accounts for units.

Study up on Lorentz force. Train your search engine...

Then you'll see what an elegant and beautifully simple thing is an electric motor.old jim

 

[tor2006]

Do you know about the force exerted on a charge that's moving in a magnetic field ? Does "Right Hand Rule " ring a bell of familiarity ?
from http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

View attachment 212741

Imagine that wire is in the armature of a motor. Current through it causes it to experience a force that turns the rotor.

Look up torque on a coil that's carrying current in a magnetic field.
from http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html#c5
View attachment 212742

Power is torque X RPM X a constant that accounts for units.

Study up on Lorentz force. Train your search engine...

old jim

I know where I made a mistake the current generates a magnetic field if we do a useful work with that magnetic field we converted the energy .for electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .copper losses reduce the magnetic field and thus reduce useful work naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right to thank you.

 

[jim hardy]

I know where I made a mistake the current generates a magnetic field if we do a useful work with that magnetic field we converted the energy .for electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .copper losses reduce the magnetic field and thus reduce useful work naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right to thank you.

I cannot possibly parse that run-on sentence.

Try rewriting that paragraph in sentences with only one thought per sentence,
and a period at end of each,
and one empty line between sentences.That discipline will help your thinking process.

The art of reasoning is nothing more than a language well arranged Laviosier...

 

[tor2006]

I cannot possibly parse that run-on sentence.

Try rewriting that paragraph in sentences with only one thought per sentence,
and a period at end of each,
and one empty line between sentences.That discipline will help your thinking process.

I cannot possibly parse that run-on sentence.

Try rewriting that paragraph in sentences with only one thought per sentence,
and a period at end of each,
and one empty line between sentences.That discipline will help your thinking process.

I know where I made a mistake

The current generates a magnetic field if we do a useful work with that magnetic field we converted the energy .

For electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .

Copper losses reduce the magnetic field and thus reduce useful work .

Naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right thank you.

 

[anorlunda]

where is other part of power the current is the current the electrons need to lose energy somewhere,

It sounds like you have the idea that electrons are little packets of energy. That's very wrong. Your learning about electric power will go much faster if you try to forget that you ever heard of electrons.

 

[Guineafowl]

I know where I made a mistake

The current generates a magnetic field if we do a useful work with that magnetic field we converted the energy .

For electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .

Copper losses reduce the magnetic field and thus reduce useful work .

Naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right thank you.

This response is a little facetious, I must say. Jim’s taken some time to explain things for you, and asked for a more clearly phrased question. You’ve just reproduced the original, garbled paragraph but with extra gaps.

We’re ready to help as long as you’re ready to listen.

 

[russ_watters]

Law of energy conservation energy is converted from one to another but i can not understand that only one part of power is lost on resistance .friction,eddy current ,hysteresise ... where is other part of power the current is the current the electrons need to lose energy somewhere, and as far as I know except the electron movement, the other energies are not needed to create the magnetic field .

I think what you are really asking isn't so much about the conversion but rather about the electrical power loss itself...

Given that amperage is constant in a circuit, power dissipation across system components is a function of voltage drop, caused by resistance. Electric motors are electromagnets, which are inductors. Inductors carry a sort of resistance which creates that voltage drop.

 

[russ_watters]

This response is a little facetious, I must say. Jim’s taken some time to explain things for you, and asked for a more clearly phrased question. You’ve just reproduced the original, garbled paragraph but with extra gaps.

We’re ready to help as long as you’re ready to listen.

Yes, @tor2006 , copying and pasting the same garbled paragraph over and over without attempting to actually respond to what people have said does not give us the impression that you are putting any effort into this. You'll need to try harder in order to keep people interested in helping you and for you to be able to learn anything from the help being given.

 

[jim hardy]

EDIT -- Thank you for re-writing your paragraph. Since other posts appeared while i was typing, I tried to quote the first two lines but apparently we can't "Quote" in edit mode.
I wasn't ignoring you, it took me about an hour to type this so i missed a lot of the conversation.
...........................

That's a LOT BETTER! Thank You !

I know where I made a mistake

First step toward understanding ...

The current generates a magnetic field .

To one way of thinking there are two magnetic fields in a motor. That of the stator and that of the rotor. They can attract or repel to do mechanical work.

if we do a useful work with that magnetic field we converted the energy .

Yes.

For electric motor is important that the current passes through the windings so it does not care about where electrons "leave "energy .

There may be more than one winding. The magnetic field that enables energy conversion mihgt be created by an electromagnet or by permanent magnets.
The winding where the actual conversion between mechanical and electrical energy takes place is called the "Armature" and that's where the Lorentz force makes that conversion .
In the examples above the moving conductor is the armature.
The magnetic field through which it passes might be made by an electromagnet or by a permanent magnet.
Whatever produces it is called "The Field".
If "The Field" is an electromagnet its windings are called "Field Windings".
The windings of the armature are of course called "Armature Windings" .

Now, that's vocabulary. It is important to use terms that lead the mind toward the correct concept.
Else we will mis-communicate."...so it does not care about where electrons "leave "energy..."
It makes a big difference where the electrons 'leave' (is 'deposit a better word?) their energy.
If they expend their energy hopping between copper atoms, that just heats the armature wires instead of making useful work.
If they expend their energy overcoming Lorentz force then they have exerted torque on the shaft and done useful work.

Copper losses reduce the magnetic field and thus reduce useful work .

Heat doesn't reduce a magnetic field.
That's the trouble with words - our mind will believe a sentence that's grammatically correct but physically wrong.
Resistance of armature wires limits (or reduces) the current available to make torque.

What is going on in the armature is the force on the charges that are moving along the wire cause torque as explained above.
Resistance only limits the rate of charge movement.
Lorentz force acts in a second way once the armature starts to rotate.

Once the wire acquires rotational velocity, its charges also acquire that velocity and right hand rule says a new Lorentz force, due to velocity of the wire, now opposes their flow along the wire.
Now, work done against THAT force is a lot different than ohmic heating.
The work done against THAT force is the "back EMF" or "Counter EMF" ,
and its product, Counter-EMF volts X armature amps, IS the electrical energy being converted into mechanical work not heat.

Now - that's way too brief an introduction to the subject .
You will have to read about electric motors and i advise you to get a few and take them apart.
It helps us to look down the bore and work out force directions by right hand rule...

Naturally within the electric motor there are several types of losses I'm interested in your opinion whether I'm right thank you.

Your words did not paint in my mind a clear picture.

But your remarkable improvement in presenting your questions tells me you will persist and refine your understanding .

Lavoisier again :

At the end of the fifth chapter, the Abbé de Condillac adds: "But, after all, the sciences have made progress, because philosophers have applied themselves with more attention to observe, and have communicated to their language that precision and accuracy which they have employed in their observations: In correcting their language they reason better."

I often recommend this article to students. It tells why attention to detail in phrasing our questions and our explanations is so important.
I especially like the paragraph near end that begins with words ""Instead of applying observation to the things we wished to know, we have chosen rather to imagine them...""

Spend the twenty minutes or so it take to read this. It can change your life.
https://web.lemoyne.edu/giunta/lavpref.html

I kept a copy framed over my desk for decades.old jim

 

[tor2006]

of course they possesses energy because electricity is a charge in motion

i should probably ignore all the laws why not

what creates heat in my radiator electron no current of potatoes

what is voltage j/c no oil is driving force for potato current

 

[Guineafowl]

Oh, dear - not a forum argument!

May I throw my hat into the ring? You’re asking about energy transfer in a motor, from current to magnetic field to rotation. How do the electrons give up their energy when all they encounter is copper resistance in the windings?

Is this a question about impedance, specifically inductive reactance as opposed to DC resistance?

 

[jim hardy]

Oh, dear - not a forum argument!

Yes a lot of posts in the last four minutes. Took me about an hour to type up # 12 so i missed a lot.

Deep breath all, let us contemplate role of " QV cross B " in motor action.

old jim

 

[jim hardy]

Aha ! I knew we had discussed Counter-EMF and Lorentz someplace before

finally found it
@tor2006

after you've read #12 you might peruse this old old post that i'd nearly forgotten
it helped me envision the physical process.

https://www.physicsforums.com/threads/direction-of-current-flow.788081/page-2#post-4982720

I think there's yet another old thread but i haven't found it.

old jim

 

[berkeman]

Thread closed for Moderation...

 

[berkeman]

Thread will remain closed. A very unpleasant post by the OP directed at a long-time trusted PF member has been deleted. OP has a 10-day vacation to think about such behavior.

 

[berkeman]

BTW, thank you to all of the posters who provided great help, despite the conditions. Thanks.