The Back emf misnomer

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wings

Re: The Back emf misnomer « Reply #25 on: 2012-12-05, 13:30:23 »

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http://www.energeticforum.com/renewable-energy/3806-back-emf-vs-collapsing-magnetic-field-spike.html

Farmhand	Re: The Back emf misnomer « Reply #26 on: 2012-12-06, 08:21:46 »
Group: Guest	Yes I do agree inductors can be complicated, I also agree that it very much depends on the perspective and how it is looked at. I do appreciate everyone's opinions, impressive responses, and for me there is always something to learn from looking at things from another's perspective. I don't wish to appear argumentative for the sake of argument, after all most of you guys have put inductors to many good uses for a long time so I will not be arbitrarily dismissing or ignoring any comments. We all know that counter emf does not actually consume from the supply. Don't we ? In a transformer it simply restricts input current and in a generator it represents the energy transferred from shaft power (mechanical force) to electrical power in my opinion. All the so called Lenz mitigating devices still output relative to the effect of Lenz. In a transformer no energy is dissipated due to counter emf. In a motor the effect of back emf does the same thing I think and in the generator it takes the form of Lenz effect kind of in an inverted way, I think. I don't think there are any losses involved in the restriction of current in a motor or transformer due to the effect of back or counter emf. The way most folks refer to back emf which I disagree with most is the recovery of the energy from the magnetic field of a coil using a diode, the coil is not charged with counter emf and it acts a source of emf to charge the battery or run the load, the way the charge battery is usually in series with the supply battery presents a counter emf to the value of the charge battery voltage, meaning because of the 12 volts above the circuit positive rail voltage when the coil discharges it faces 12 volts (counter emf) automatically, if two 12 volt batteries are charged in series, and those two are in series with the supply battery then the emf produced by the coil faces 24 volts (counter emf) automatically. if there is any inductance in the discharge path then the emf of the discharging coil is opposed by counter emf produced by that as well because it is causing a change in the current. In the case of AC sine wave then the emf is constantly changing and so on the decline of the wave there is a constant discharge of magnetic field energy which appears as emf right along with and aiding the applied emf. After all the energy discharged from the coil was from the applied emf. Anyway it is an interesting subject. Thanks for the replies so far. EDIT: (some edits made for clarity, I hope ) Hi Wings, yes that thread does explain some things, that thread needs to be linked in the Don Smith thread on that other forum. Thanks for digging that up. I'm not sure anyone here requires tuition from Aaron though, meaning no disrespect, to anyone. ..

GibbsHelmholtz	Re: The Back emf misnomer « Reply #27 on: 2012-12-06, 14:01:16 »
Group: Guest	I've been doing some research and simulation on transformer loading. When we load the secondary, the magnetic field interaction between two winding cause more input. We can simulate secondary loading by input artificial current through the secondary. Better yet, we can use magnet to simulate secondary loading. So far on the sim, I cannot see how this would not work. What if we have a watt meter connect to a transformer. Instead of loading the secondary, place a strong magnet to the transformer core to simulate loading. What would be observed on the watt meter?

Farmhand	Re: The Back emf misnomer « Reply #28 on: 2012-12-06, 19:17:09 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-06, 14:01:16 I've been doing some research and simulation on transformer loading. When we load the secondary, the magnetic field interaction between two winding cause more input. We can simulate secondary loading by input artificial current through the secondary. Better yet, we can use magnet to simulate secondary loading. So far on the sim, I cannot see how this would not work. What if we have a watt meter connect to a transformer. Instead of loading the secondary, place a strong magnet to the transformer core to simulate loading. What would be observed on the watt meter? Not much would happen with the Watt meter because there is still no load, if no energy is taken out of the transformer then only losses would be replaced as far as energy goes, the Watt meter might show some extra Watts due to reactive power there could be more losses as well. Main point is there would not be a significant continuous input unless significant energy is taken out. Cheers

BEP	Re: The Back emf misnomer « Reply #29 on: 2012-12-07, 00:06:57 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-06, 14:01:16 What if we have a watt meter connect to a transformer. Instead of loading the secondary, place a strong magnet to the transformer core to simulate loading. What would be observed on the watt meter? The watt meter would show increased energy usage. How much depends upon how strongly your applied magnet can saturate the core of the transformer. Keep in-mind that all you are doing is decreasing the inductive reactance of the transformer and therefore creating more current through the primary. The energy will be lost as heat. A more controllable method is to connect the secondary to the primary reversed polarity - then insert a suitable variable resistor between a primary and secondary wire so you can control the effects. This can be dangerous when using a transformer not rated to work as a reactive load element. Almost all reactive load elements you can buy have the losses controlled by fixed spacing gaps in the core lamination. These are typically used to add to resistive loadbanks to bring the power factor of the test load closer to real-world loads. Google 'Simplex' or 'Avtron' load banks. Both should have a technical paper covering the types of load banks. I know Avtron did have one. I participated in the writing of it

GibbsHelmholtz	Re: The Back emf misnomer « Reply #30 on: 2012-12-07, 05:43:34 »
Group: Guest	A real pro, That's what I have in mind. This is also what I see when the secondary is loaded. It must has a similar effect causing input to increase. I would not say secondary loading saturate the core, but primary and secondary current making the domain reluctant to move. Though the material does not saturate itself, it is no differ from saturation phenomena. Saturation should cause inductance to decrease, so inductive reactance decreased. Maybe we should rethink transformer operation.

exnihiloest	Re: The Back emf misnomer « Reply #31 on: 2012-12-07, 09:05:58 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-06, 14:01:16 I've been doing some research and simulation on transformer loading. When we load the secondary, the magnetic field interaction between two winding cause more input. We can simulate secondary loading by input artificial current through the secondary. Better yet, we can use magnet to simulate secondary loading. So far on the sim, I cannot see how this would not work. What if we have a watt meter connect to a transformer. Instead of loading the secondary, place a strong magnet to the transformer core to simulate loading. What would be observed on the watt meter? A transformer presents an input impedance R+L in series, where R is the resistance of the primary coil and L its inductance. In a good transformer, L must represent a high impedance at the working frequency. Therefore only a weak leakage current flows in the primary (if the secondary is open). If you put a magnet that saturates the transformer core, L decreases, the impedance becomes low, and consequently a current that can be very strong flows in the primary. Note that if you put a magnet, you don't really simulate a loaded transformer, because the secondary plays no role, no current flows in the secondary, what is not the case when a real load is connected to the secondary and its resistance is also concerned. « Last Edit: 2012-12-07, 14:47:28 by exnihiloest »

Farmhand	Re: The Back emf misnomer « Reply #32 on: 2012-12-07, 10:31:17 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-06, 14:01:16 What if we have a watt meter connect to a transformer. Instead of loading the secondary, place a strong magnet to the transformer core to simulate loading. What would be observed on the watt meter? The Watt meter will show the reactive power if that is what it is set to, if it is set to real power, as some can be only the real power will be shown. I was considering real power when Watts was stated. The real power shown would only be representing the losses I think. Which should be not that much. With respect to simulated loading, real power is the value to take into account. And with no load actually drawn the real power can only represent the losses. Cheers

BEP	Re: The Back emf misnomer « Reply #33 on: 2012-12-07, 11:04:48 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-07, 05:43:34 A real pro, That's what I have in mind. This is also what I see when the secondary is loaded. It must has a similar effect causing input to increase. I would not say secondary loading saturate the core, but primary and secondary current making the domain reluctant to move. Though the material does not saturate itself, it is no differ from saturation phenomena. Saturation should cause inductance to decrease, so inductive reactance decreased. Maybe we should rethink transformer operation. My mistake. You are correct. I should have said the primary current increases since the primary inductive reactance decreases. I was thinking in terms of the reactive load increasing (inductive reactance decreasing). When the secondary is not connected the transformer is no longer a transformer. It is simply an inductor. Transformer theory no longer applies. ----So often we don't know when to stop applying rules and theories to something when it looks like it hasn't changed Remember that current lags voltage when a load has inductance. The inductor absorbs energy from the circuit and then equally returns energy to the circuit, so a pure reactance doesn't dissipate power. You will not have a pure reactance, so you will dissipate some power. How much depends upon how good you are at introducing losses. Control core saturation curves and inject core losses: a) use other windings as control windings via the same methods used in mag-amps b) replace some lamination with air or aluminum to create eddy current losses. c) apply magnets to the core - your magnet best be very large and/or powerful These losses will appear on the watt meter just as surely as the losses in the transformer secondary loads.

GibbsHelmholtz	Re: The Back emf misnomer « Reply #34 on: 2012-12-07, 14:12:35 »
Group: Guest	Quote from: exnihiloest on 2012-12-07, 09:05:58 Note that if you put a magnet, you don't really simulate a loaded transformer, because the secondary plays no role, no current flows in the secondary, what is not the case when a real load is connected to the secondary and its resistance is also concerned. This is what I want to know. What exactly is the difference between two cases. They both seems to increase input, they both interact via magnetic field. The magnet has current that seems to represent secondary current.

GibbsHelmholtz	Re: The Back emf misnomer « Reply #35 on: 2012-12-07, 14:34:19 »
Group: Guest	Quote from: Farmhand on 2012-12-07, 10:31:17 The Watt meter will show the reactive power if that is what it is set to, if it is set to real power, as some can be only the real power will be shown. I was considering real power when Watts was stated. The real power shown would only be representing the losses I think. Which should be not that much. With respect to simulated loading, real power is the value to take into account. And with no load actually drawn the real power can only represent the losses. Cheers The Watts meter is set to real power. When you put a magnet to the core, more current flow through the primary and real power reading increase.

exnihiloest	Re: The Back emf misnomer « Reply #36 on: 2012-12-07, 14:53:03 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-07, 14:12:35 This is what I want to know. What exactly is the difference between two cases. They both seems to increase input, they both interact via magnetic field. The magnet has current that seems to represent secondary current. These cases are completely different. With the magnet you have a R-L circuit, not a transformer, the open secondary plays no role. The losses are not the same, the U/I phase are not the same and so on...

BEP	Re: The Back emf misnomer « Reply #37 on: 2012-12-08, 00:08:14 »
Group: Guest	Gibbs, Quote from: exnihiloest on 2012-12-07, 14:53:03 These cases are completely different. With the magnet you have a R-L circuit, not a transformer, the open secondary plays no role. The losses are not the same, the U/I phase are not the same and so on... And I stated earlier: Quote When the secondary is not connected the transformer is no longer a transformer. It is simply an inductor. Transformer theory no longer applies. The magnet isn't creating losses exactly the same way as a loaded secondary. The losses created by applying a magnet create transformer core losses by changing the saturation curve. Mag-amps use the same principle to control loads by changing the saturation curves and/or X_L of the Mag-amp in series between the power source and load with a small DC control signal.

GibbsHelmholtz	Re: The Back emf misnomer « Reply #38 on: 2012-12-08, 01:22:04 »
Group: Guest	Quote from: WaveWatcher on 2012-12-08, 00:08:14 And I stated earlier: The magnet isn't creating losses exactly the same way as a loaded secondary. The losses created by applying a magnet create transformer core losses by changing the saturation curve. Thanks WaveW, I thought by having the magnet, core losses becomes less? Besides, current increase means more losses to wire resistance, not core? Yes, I understand that Exn. also say they are differ, but can it be more specific? For example. When the secondary is loaded, what happens to primary current? When secondary is loaded, what happens to phase? When magnet is biased, what happens to primary current? When magnet is biased, what happens to phase?

exnihiloest	Re: The Back emf misnomer « Reply #39 on: 2012-12-08, 08:43:16 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-08, 01:22:04 ... Yes, I understand that Exn. also say they are differ, but can it be more specific? For example. When the secondary is loaded, what happens to primary current? When secondary is loaded, what happens to phase? ... Like to compare potatoes and carots. Not the same color, not the same shape, not the same genetics... Take the equivalent transformer schematic and do the math in both cases. ------------------------ The Back emf misnomer TransfEq.jpg (12.77 kB, 654x214 - viewed 1540 times.)

GibbsHelmholtz	Re: The Back emf misnomer « Reply #40 on: 2012-12-08, 13:49:55 »
Group: Guest	Quote from: exnihiloest on 2012-12-08, 08:43:16 Like to compare potatoes and carots. Not the same color, not the same shape, not the same genetics... Take the equivalent transformer schematic and do the math in both cases. Well... I take it that loading secondary cause primary current to increase and making it more in phase. lol So does biasing the magnet. The only differ that would be in question is that there is no stored field in transformer while there is stored field in coil.

Allcanadian

Re: The Back emf misnomer « Reply #41 on: 2012-12-08, 21:23:04 »

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@Gibbs

Quote

Well... I take it that loading secondary cause primary current to increase and making it more in phase. lol So does biasing the magnet. The only differ that would be in question is that there is no stored field in transformer while there is stored field in coil.

I think the best way to really learn is to experiment and prove the matter for yourself. Consider the fact that what you seek has been considered to be impossible therefore no matter how smart the critics may consider themselves to be at best they can only tell you their opinion of what they think doesn't work. A non-working unit is pointless.

On another note, the storing of energy in a magnetic field is dependent on the dynamics of the field and if a core is saturated then how could we expect it to store anything more. I dug up one example for you, the picture below is one channel from an Arduino based hall effect magnetometer I built to prove matters for myself. It is measuring only the magnetic field intensity from a laminated open inductor in series with a switched resistive load. Note this is not a coil sensor measuring induced voltage it is an independent sensor measuring only the field intensity a known distance from the core.
Now how does this measure of only the magnetic field relate to the current flow in the windings?, why is the peak falling with each current impulse?. Now if the initial current flow is impeded by the self-inductance of the coil then why is the field strength maximum when the current is lowest?. This can easily be explained by what is common knowledge however it is best that you answer these questions for yourself because that is the way we really learn and understand things.

AC

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The Back emf misnomer

Saturation.jpg (99.62 kB, 998x398 - viewed 745 times.)

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Comprehend and Copy Nature... Viktor Schauberger

“The first principle is that you must not fool yourself and you are the easiest person to fool.”― Richard P. Feynman

GibbsHelmholtz	Re: The Back emf misnomer « Reply #42 on: 2012-12-09, 01:44:37 »
Group: Guest	Thanks AC, I have my own questions and do things on my own but mostly to verify. So far I found what established is pretty solid. In my opinion, the problem with free energy isn't something technical but rather something overlooked. Getting too deep may get ourselves lost. My general conclusion for abundant energy is relative motion and magnetic field. Relative motion is everywhere since the universe is dynamics. Magnetic field can be created strong at low cost. A strong field can be create with resonance. The question is could the magnetic field turn random motion into something useful. I'm stuck at this for now.

EMdevices

Re: The Back emf misnomer « Reply #43 on: 2012-12-09, 16:02:31 »

Hero Member

Posts: 805

Ah, Good old "back EMF", let's see, what heretical thing can I say about it?

Well, if we can cancel this effect we have to first cancel or invalidate Faradays law of induction, which would mean a changing magnetic field would no longer produce or induce an electric field. Bye bye electro DYNAMICS! All will be left with is statics, how boring!

No, we don't want to cancel the back EMF, which is the induced voltage from the changing current's own magnetic field and has a polarity that acts "back" against the current, no we don't want to do that we can't, instead we can be clever and work at fempto seconds before the back emf effect reacts against the whole coil. I dont think those MIT brain heads thought of that yet!

EM

forest

Re: The Back emf misnomer « Reply #44 on: 2012-12-10, 06:50:05 »

Sr. Member

Posts: 478

Nobody really answered what is the back EMF. Clearly when I think about it this effect do not occur when the secondary of transformer is opened. This tell me it's related to reflection of energy wave and most particularly to the current flow ! That also means Tom Bearden is probably right about the relaxation time and the most desired experiemnt is to confirm it with long relaxation time material.....

GibbsHelmholtz	Re: The Back emf misnomer « Reply #45 on: 2012-12-10, 13:31:07 »
Group: Guest	While experimenting, I stumble upon this result. When the coil is moving back and forth with just one magnet, the signal reading is high. (illustrated in Indo1) When the coil is moving back and forth with both magnets, the signal reading is low. (illustrated in Indo2) Why is this? ------------------------ The Back emf misnomer Indo1.png (6.22 kB, 680x384 - viewed 584 times.) The Back emf misnomer Indo2.png (8.88 kB, 680x384 - viewed 731 times.)

forest	Re: The Back emf misnomer « Reply #46 on: 2012-12-10, 13:45:41 »
Sr. Member Posts: 478	Bravo Gibbs This is the solution

BEP	Re: The Back emf misnomer « Reply #47 on: 2012-12-11, 00:45:45 »
Group: Guest	Quote from: GibbsHelmholtz on 2012-12-10, 13:31:07 While experimenting, I stumble upon this result. When the coil is moving back and forth with just one magnet, the signal reading is high. (illustrated in Indo1) When the coil is moving back and forth with both magnets, the signal reading is low. (illustrated in Indo2) Why is this? Because the two magnets have field density between them that has less change while moving. If you wish to see stronger signal, align the two magnets so they repel each other (assuming the same distance and velocity of movement.)

GibbsHelmholtz	Re: The Back emf misnomer « Reply #48 on: 2012-12-11, 00:56:23 »
Group: Guest	Quote from: WaveWatcher on 2012-12-11, 00:45:45 Because the two magnets have field density between them that has less change while moving. If you wish to see stronger signal, align the two magnets so they repel each other (assuming the same distance and velocity of movement.) Thanks WaveW, Can we establish a field that would show constant flux between? If the magnets move closer together, will the flux change?

BEP	Re: The Back emf misnomer « Reply #49 on: 2012-12-11, 02:30:22 »
Group: Guest	The flux density will never be perfectly uniform between attracting magnets. If the coil is the same diameter as the magnets you should find a distance between magnets where the density is almost uniform and therefore create little to no induction in the movements shown. If you move them closer the density increases. No matter what orientation you choose a change in flux density occurs and will induce an emf in the coil. What is the goal of these experiments?