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Author Topic: MH's ideal coil and voltage question  (Read 477922 times)

ramset

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Re: MH's ideal coil and voltage question
« Reply #585 on: May 19, 2016, 04:15:41 PM »
TinMan extends a Kind hand in a peaceful gesture to move forward!
 MileHigh wants more Blood ,and curls The Lip?


tinman

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Re: MH's ideal coil and voltage question
« Reply #586 on: May 19, 2016, 04:28:01 PM »
Brad:

I am going to ask you the question again:

Way back very early in the thread I posted that formula and told you that it was basically the short answer to the question.  When I did that you went into a small frenzy and you insulted me like a drunk sailor.  So what gives, how do you explain using the formula now when before when I showed you the very same formula you insulted me repeatedly like a drunk sailor?

MileHigh

OK MH
I will try and explain this one more time.
1st-As i said,i was giving back as good as i was getting,as far as your insulting go's.
I would like to point you toward post two,the very second post on this thread,and your very first post on this thread-->quote: You are one strange egg Brad because you think you are "running the show" now but in fact the show is running you.
1.  Brad gets up the learning curve and understands the original question and then answers it correctly all by himself and clearly demonstrates that he understands what he is doing.
2.  Brad admits that he is wrong when he stated that my response to the harder question is wrong.


You will see my first post said--Please keep the insults down,and the language clean.
And my last line in that post was-->For the record,could you please post your answer to your question above?
As you can see,i asked for insults to be kept down,and also asked you very politely to post your answer. So i think you can see from just the first two posts on this thread,who wanted it to run smooth without insults,and who was the first to cast the first insult--and it just escalated from there.
Perhaps you should go and read the first page of the thread,and see who was demeaning to who.

2nd- As i have already tried to explain to you,i do not agree that the formula being used is correct from T=5 seconds to T=7 seconds. I only used your formula to show you that i am quite capable of dealing with generic formulas,and calculating generic results. I told you i could do this very early in the thread--perhaps you thought i could not. All the information to do so is on the net,and i can learn very quickly.

But once again,i only gave you what you wanted to see,and i gave it correctly.
But as i have said on more than one occasion now,this dose not mean that i believe them to be correct in this situation. In a non ideal situation,this collision of energy would be burnt of as heat,via the internal resistance of the voltage source and the coil it self. But being that we are in an ideal situation,this collision energy cannot be dissipated as heat,as there is no series resistance in the circuit.


Brad

tinman

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Re: MH's ideal coil and voltage question
« Reply #587 on: May 19, 2016, 04:45:27 PM »
The point of asking you to draw out the wave form not so we can just dismiss it, it is to see how your thinking has caused you to arrive at your theory, and to see how to steer you toward the correct understanding. Yes of course your wave form trace is correct. It is not MH's way btw, it is just how it is, it is physics and it is reality (even with an ideal or near-ideal inductor).
I would use the formula MH posted. But I prefer to use the sim, which btw, fully supports the formula and the graph you have drawn out.

As i said,you are not interested in what i have to say,as you have stated that you wish to !!steer!! me in the right direction.
I have already stated my concerns,and why--several times now,but maybe you missed them all.

How will the steady state current flow of 2.4 amps effect the seen inductance value by the EMF that wishes to induce a current flow in the opposite direction at T=5 second's?. The reason i ask this,is because that current flow of 2.4 amps,will be seen as a high value impedance to the current trying to be induced during the negative voltage part of the cycle. At the moment,the current value for T=7 seconds, is being calculated on the assumption that the inductance value seen by the now negative EMF is still 5H. I am only asking if this higher impedance value,due to the !already flowing! 2.4 amps of current acting against the current that the negative EMF is trying to induce,will alter the inductance value seen by that negative EMF.

To me it seems that the EMF will see a different inductance value,and there for a different impedance value,when the coil has no current flowing through it at T=0, to that when the current flowing through it is 2.4 amps,but of opposite polarity.

To make this clear,please see diagrams below to see the difference that i am trying to explain.

Brad

wattsup

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Re: MH's ideal coil and voltage question
« Reply #588 on: May 19, 2016, 05:48:31 PM »
@tinman

At least I agree with you the the wave form should not be like that but maybe for another reason.

For me, ideal voltage has zero resistance, ideal inductor has zero resistance so at 4 seconds when the voltage suddenly drops to 0 volts, what is 0 - 0 - at 0 is just like an inductor being disconnected and what happens when an inductor is disconnected especially at 5H, should create a good discharge of the 2.4 * 4 = 8.8 watts. Some will hit back into the ideal voltage but most will just dissipate.  At least in real life if you had a 5H coil in your hand changed at 4 volts and 2.4 amps and if you just turned off the power supply, good luck.

So each zero point for me is like an inductive discharge.

Again what is missing is data is the question. We have to suppose to many things. Is it DC ideal voltage. If so then the applied negative is always at zero volts and the positive is the one changing voltage at t0 and at t4 and t6, but then at t6 to t8 both polarities are switched for the applied -3 while the volt meter stays were it is, so you have a different effect because both ends of the ideal voltage are changed.

Anyways, I guess the answer has to be as lazy as the question.

Or, you have to do like 1000 EE students probably have to do when they are confronted with this question is to just play the game, don't break your head, say yes yes yes and just pass. hahahaha

wattsup


poynt99

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Re: MH's ideal coil and voltage question
« Reply #589 on: May 19, 2016, 05:53:22 PM »
As i said,you are not interested in what i have to say,as you have stated that you wish to !!steer!! me in the right direction.
I have already stated my concerns,and why--several times now,but maybe you missed them all.

How will the steady state current flow of 2.4 amps effect the seen inductance value by the EMF that wishes to induce a current flow in the opposite direction at T=5 second's?. The reason i ask this,is because that current flow of 2.4 amps,will be seen as a high value impedance to the current trying to be induced during the negative voltage part of the cycle. At the moment,the current value for T=7 seconds, is being calculated on the assumption that the inductance value seen by the now negative EMF is still 5H. I am only asking if this higher impedance value,due to the !already flowing! 2.4 amps of current acting against the current that the negative EMF is trying to induce,will alter the inductance value seen by that negative EMF.

To me it seems that the EMF will see a different inductance value,and there for a different impedance value,when the coil has no current flowing through it at T=0, to that when the current flowing through it is 2.4 amps,but of opposite polarity.

To make this clear,please see diagrams below to see the difference that i am trying to explain.

Brad
Brad, the honest truth is that I don't understand your explanation nor your questions. I can't make sense of them. So rather than spending my time trying to understand your theory, I asked you to plot out your current trace according to your understanding, which gives me instant insight into your thinking. Then I might have a chance of steering you in the right direction. But you state that you can not plot out the current according to your theory, while at the same time, rejecting the present accepted theory which is not only predicted by equation and simulation, but makes sense from the conceptual point of view. I think if you are going to reject a theory, you should have one the you feel is the correct one, and be able to explain it and prove that the existing one is incorrect. So far I have not seen this from you.

SeaMonkey

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Re: MH's ideal coil and voltage question
« Reply #590 on: May 19, 2016, 08:46:03 PM »
Quote from: Miles Higher
...like a drunk[en] sailor?

Aye, to you Land-Lubbers it is just an expression. ;)

To those of us who crewed the "haze gray and underway"
men o' war it was a way of life.  Extended periods at sea
develop quite a thirst in the Sailor and when finally in
port to enjoy some "Liberty" sipping the brew was a joyous
relief. ;D

Naturally, too much of the brew leads to some really
odd behaviors which the Sailor is naturally inclined to
indulge in.  Hence, the expression of the Land-Lubbers. 8)

Sailors are not offended by the expression. :)

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #591 on: May 19, 2016, 09:52:19 PM »
2nd- As i have already tried to explain to you,i do not agree that the formula being used is correct from T=5 seconds to T=7 seconds.

Brad

Please tell us in your own words what the formula means.

partzman

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Re: MH's ideal coil and voltage question
« Reply #592 on: May 19, 2016, 10:53:05 PM »
I have taken the liberty of changing MH's original problem sightly so there is now a period following T3 to T5 from T5 to T8 with -4 volts applied to the 5H inductor. This is equal to but opposite the initial T0 to T3 so we can now see what happens to the inductor current.

One might find it easier to visualize the magnetic field around the inductor and how it varies in relation to the current.  I've included an algebraic proof of this relationship.

      𝑬𝒎𝒇 = - 𝑵 × 𝚫𝚽/𝚫𝒕    (Faraday’s Law)
      𝑬𝒎𝒇 = - 𝑳 × 𝚫𝑰∕𝚫𝒕       (Inductance defined in terms of Emf)
      ∴ 𝑵 × 𝚫𝚽/𝚫𝒕 = 𝑳 × 𝚫𝑰∕𝚫𝒕   (Substitution)
      ∴ 𝑵 × 𝚫𝚽 = 𝑳 × 𝚫𝑰   (Reduce)
      ∴ 𝑳 = 𝑵 × 𝚫𝚽∕𝚫𝑰      (Inductance in terms of flux)
      ∴ 𝚫𝚽 = 𝑳 × 𝚫𝑰           (Flux over time verses inductance and current over time with 1 turn)

partzman

edit



partzman

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Re: MH's ideal coil and voltage question
« Reply #593 on: May 19, 2016, 11:22:37 PM »
Thank you Partzman,

So the input to spin up the flywheel is the same as is required to stop it.

Yes, in that analogy you are correct.

partzman

verpies

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Re: MH's ideal coil and voltage question
« Reply #594 on: May 20, 2016, 01:11:51 AM »
In spirit of the thread lets consider an ideal ferromagnetic as a break from the ideal voltage sources.
What properties would such material have?

For sure it wold not exhibit any hysteresis loss and it would not heat up at all when immersed in a changing magnetic flux.
It would not conduct electric current at all so Eddy currents could not form in it.
Would it have infinite permeability? - I don't think so, anymore than an ideal inductor needs to have an infinite inductance.

What are your thoughts?
What other properties would an ideal ferromagnetic have?

tinman

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Re: MH's ideal coil and voltage question
« Reply #595 on: May 20, 2016, 01:18:55 AM »
Brad, the honest truth is that I don't understand your explanation nor your questions. I can't make sense of them. So rather than spending my time trying to understand your theory, I asked you to plot out your current trace according to your understanding, which gives me instant insight into your thinking. Then I might have a chance of steering you in the right direction. But you state that you can not plot out the current according to your theory, while at the same time, rejecting the present accepted theory which is not only predicted by equation and simulation, but makes sense from the conceptual point of view. I think if you are going to reject a theory, you should have one the you feel is the correct one, and be able to explain it and prove that the existing one is incorrect. So far I have not seen this from you.

The inductance value is being used to calculate the peak current at T=7 seconds,but the induction process to make this calculation is not correct between the time period T=5 seconds to T=7 seconds. The inductance value being used to make this calculation is not correct. We have started at T=5 seconds,and ended at T=7 seconds to calculate the peak current reached at T=7 seconds. This is on the understanding that the induction process taking place at this time will start with no current flowing through the coil,and no existing magnetic field. We apply our voltage,and current starts to flow,and a magnetic field begins to build(induction). We calculate that using a 5H coil,the peak current value reached at T= 7 seconds will be 1.2 amp's. But as i said,this assumes that there is no current flowing through the coil. This assumes that a current will begin to flow,a magnetic field will begin to form,and the CEMF value will fall as the magnetic fields change in time reduces.

But what we actually have happening here is the opposite.
A current flow and magnetic field already exist .
The current dose the exact opposite to what the calculations we are using say it should.
The current dose not start from 0 and rise to 1.2 amps,it starts from 2.4 amps and falls.
The CEMF produced from this !once again! magnetic field that is changing in time,is now the same as the EMF that created it,and dose not appose it as it should the way we have made the calculation for the time period of T=5 seconds to T=7 seconds.

So we have used a calculation to gain a peak current value at T=7 seconds, that go's on the premise that there will be a Counter EMF--this give us our current rise over time value.
But what we actually have is a current value drop over time,not a rise,and no CEMF,but an EMF  working with the induced EMF.

So it would seem to me,that the formula used to calculate the peak current value at T-7 seconds,is not the correct formula to use.
If we have no CEMF but an EMF that is not apposing the inducing EMF,then there is no impedance/resistance to to the induced current flow.
So it makes sense that the current flow would sky rocket instantly,as there is no resistance/impedance to slow or stop it.


Brad

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #596 on: May 20, 2016, 03:02:20 AM »
Brad:

Let's back up and discuss the inductor impedance over the first three seconds.  We all know the drill now, the five Henry inductor makes contact with the ideal voltage source, and for the first three seconds the voltage is four volts.

What is the impedance of the inductor over the fist three seconds?

MileHigh

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #597 on: May 20, 2016, 03:03:45 AM »
I have taken the liberty of changing MH's original problem sightly so there is now a period following T3 to T5 from T5 to T8 with -4 volts applied to the 5H inductor. This is equal to but opposite the initial T0 to T3 so we can now see what happens to the inductor current.

One might find it easier to visualize the magnetic field around the inductor and how it varies in relation to the current.  I've included an algebraic proof of this relationship.

      𝑬𝒎𝒇 = - 𝑵 × 𝚫𝚽/𝚫𝒕    (Faraday’s Law)
      𝑬𝒎𝒇 = - 𝑳 × 𝚫𝑰∕𝚫𝒕       (Inductance defined in terms of Emf)
      ∴ 𝑵 × 𝚫𝚽/𝚫𝒕 = 𝑳 × 𝚫𝑰∕𝚫𝒕   (Substitution)
      ∴ 𝑵 × 𝚫𝚽 = 𝑳 × 𝚫𝑰   (Reduce)
      ∴ 𝑳 = 𝑵 × 𝚫𝚽∕𝚫𝑰      (Inductance in terms of flux)
      ∴ 𝚫𝚽 = 𝑳 × 𝚫𝑰           (Flux over time verses inductance and current over time with 1 turn)

partzman

Thank you, excellent and very informative and enlightening post, especially the new voltage and current vs. time graph.

MileHigh

Magluvin

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Re: MH's ideal coil and voltage question
« Reply #598 on: May 20, 2016, 06:12:52 AM »
In spirit of the thread lets consider an ideal ferromagnetic as a break from the ideal voltage sources.
What properties would such material have?

For sure it wold not exhibit any hysteresis loss and it would not heat up at all when immersed in a changing magnetic flux.
It would not conduct electric current at all so Eddy currents could not form in it.
Would it have infinite permeability? - I don't think so, anymore than an ideal inductor needs to have an infinite inductance.

What are your thoughts?
What other properties would an ideal ferromagnetic have?

I understand fully. But its just pretend world. Anything can be whatever one may want it to be.

Ive been delving back into the resonance projects. Its not pretend. As Ive read over things here, Ive lost interest. Was thinking, as you just did above, of all the hows and whys of it all and it just plain isnt required as the rules are set. So pretty much all the ideal components and equipment are virtually limitless. Pioneer used to make a set of 6x9 speakers back in the early 80s. The magnets were bigger than any other that have been made. The max power handling was labeled 'Unlimited'. It wasnt that they were not telling the truth really. There just wasnt any car amplifiers in those days that exceeded or even came close to the real power handling of the speakers. So in that world back then, they were unlimited in power handling.  ;) They were ideal in that world. ;D

Mags

tinman

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Re: MH's ideal coil and voltage question
« Reply #599 on: May 20, 2016, 08:06:13 AM »
Brad:

Let's back up and discuss the inductor impedance over the first three seconds.  We all know the drill now, the five Henry inductor makes contact with the ideal voltage source, and for the first three seconds the voltage is four volts.

What is the impedance of the inductor over the fist three seconds?

MileHigh

Well,as the impedance is just a resistance to the current that wants to flow,is it correct to say that the impedance is a result of the CEMF?,--as we know,there is no ohmic resistance.