Yet another curiousity regarding the application of amps underload

[headhunter]

I've been trying to picture in my mind exactly how more amps are required and why, when an electric motor is underload.  I have really 2 questions the second might not apply.

Ok... my theory on why the motor requires more amps as it's underload.  Essentially is that the coils need to be on longer in order to keep it running at the speed that it's supposed to be.  That statement is probably wrong... it's most likely a combination, I would think the motor wants to run at a certain speed and requires more juice to power the coils so they're stronger to keep the motor happy.  So if someone can straighten that out with a somewhat easy to read response.  Thanks.

The second question/experiment.  Lemme lay it out for you before I ask.  

Assume you have one coil, no magnets.  In order to energize the field you add + one end and - the other.  Now in order to do that, it required so much amps(no idea on amps but say 1 for theory and volts are constant).

Now the next three scenereos are similar but with magnets, say you had one magnet under one leg and another opposite magnet under the other leg of the coil.  When you energize it, would it require less energy(amps) to power it up than with no magnetic fields at all? I'm leaning both ways on this one... it seems this would require less amperage but I also think it needs more amps because there would be some bickering in the manipulation of the new fields in conjunction with the magnets already there.

Ok, now what if it was the opposite, what if the coil had to fight in order to energize it up thereby eating more amps to be all it can be?  Would this be a correct assumption?

And thirdly... what about if you have both magnets facing... oh say north and powered up the coil, I'm assuming the one leg of the coil that would fight would need more amps to power up and the one side of the coil that didn't have to fight use less(assuming energizing with magnetic fields properly aligned required less amps)...

Well there ya go... this has been picking my brain... if more clarification is req'd I can do up something in flash and see what I mean.

Thanks in advance.

Ivan.

[drdongle]

A motor requires more amps ( power is messured in watts or VxA ) when under load because it is performing more work. Just like an internal combustion engine the more work it performs the more fuel that is required.

[headhunter]

I understand its using more amps while underload but the real question is what is happening exactly.  Is it the increase in heat that is taking up more energy, the fact that the coils need to be powered longer, does it need more amps to increase the strength of the magnetic field etc...

That's why I posted the second question/experiment, because I believe a portion of this increase in energy consumption is the coils having to create magnetic fields inside of other(permament magnets) fields, and require more energy when the megnets aren't helping them but opposing them.

So any ideas on what exactly is happening underload to account for the extra amps?

Ivan.

[headhunter]

I've been trying to think up a simplier way to get the answer I was looking for(that the fields are more or less the source of the amp drain or usage).  Now we can assume water is similar to electricity, atleast I've heard that term a couple times before and makes sense.  

In a transformer you have 2 sets of coils, one powering the other.  The transformer isn't underload until one side of the coil is powering up a device.  Sooooooo... if this was water... hmmm... with say... a water wheel in between the coils(one side directly affects the other)... then more energy is required when the wheel is increasing on preassure from one side.  The only way that would occur is if the magnetic fields were responsible for the amps... i think.

So... it would seem to use less amps(water preassure) if the fields were the same as the pulse... than if the field wasn't already there?

Sorry if this seems muddled, just writing as I'm thinking...

Sooo... just to reiterate... 2 magnets 2 legs of a single coil

powering coil with no fields =1

powering coil with correct fields already in place <1 or =1

powering coil with one correct field and one opposing field =? 1?

powering coil with both legs having opposing fields >1

How wrong am I?

Thanks in advance

Ivan.

[finnsawyer]

For the transformer what happens on the output affects the input.  This is modeled somewhat by the following equations:

                             V1 = L1(dI1/dt) + M21(dI2/dt)

                             V2 = L2(dI2/dt) + M12(dI1/dt)

Where the M's are the "mutual" inductances caused by the fact that the same magnetic flux passes through both coils.  Since the number of turns in each coil is different, so are they.  L1 and L2 are the self inductances of the coils.  The other terms (dI1/dt and dI2/dt) are the time rate of change of the currents.  So hanging a load such as a resistor on the output will affect the input current.

[headhunter]

that's the kind of info I was looking for... thanks.

Ivan.