I did some googling on magnetic saturation... (some parts of the post have been removed)
----- Original Message ---- > From: Stephen A. Lawrence <sa...@pobox.com> > To: vortex-l@eskimo.com > Sent: Sat, February 13, 2010 10:32:48 PM > Subject: Re: [Vo]:latest from Naudin on the Orbo > >>> KEY 3 : The electrical power (Current * Voltage ) needed to > >>> energize the toroidal stator coil at the TDC position is EQUAL to > >>> the electrical power for the REF position and this is fully > >>> independant of the position of the magnet of the rotor Vs the > >>> toroidal stator coil. The electrical input power is fully > >>> decoupled from the output mechanical power. > >> > >> Now it may not matter with regard to the final analysis of this > >> motor (which probably must depend on calorimetry), but it's > >> interesting to note that this several times repeated assertion is > >> FALSE. This can be seen by simple reasoning, and by looking at his > >> curves. > >> > >> First, simple reasoning: When the magnets are present, the > >> inductance of the coil is lower. So, by definition of inductance, > >> when the voltage is turned on, the current is going to rise and > >> fall *faster* with the magnets present than with them absent. That > >> means total power going in during turn-on is going to be higher > >> with the magnets present than with them absent, and total power > >> going in during turn-off is going to be lower with the magnets > >> present than with them absent. Consequently, power consumed is > >> going to be larger if the magnets are brought to the coil, the > >> power is turned on, the magnets are removed, and power is turned > >> off, than it would be if the magnets were either left far away > >> throughout the cycle, or were left adjacent to the coil throughout > >> the cycle. > >> > >> Second, look at the curves: The power curve, shown most of the way > >> down the web page, is clearest on this point. > > The graph in question appears to be a hand-overlaid plot of two scope > traces. It was replaced with an updated version after I wrote the above > statement. > The original version appeared as I described; the later version does > not. Assuming the new version is a correction, presumably because the > two graphs were slightly off register in the original version, the > earlier one shows an artifact of the overlay process, rather than an > actual effect, and that *artifact* is what I was describing. > > Sigh... OK > > > > > If this is also correct then it is inaccurate to equate the > > saturation of the core with a form of shielding. > > Oh, I don't know. I'd call it a "shield" in that it shuts off the > effect of the outside field. You could call it a cloak, if you prefer, > but I don't see the significance in the distinction. > > I mean, you turn the coil on and the box with the magnets drops to the > floor -- the coil's core is totally dead as far as the magnets are > concerned! How much more "shielded" can you get? > > > > > > Shielding implies resistance to penetrative forces, so a shield is > > only as effective as the force it can block, consequently the power > > requirements of a shield are proportional to the external penetrative > > forces. > > I disagree. The power requirements of a shield are, a priori, unknown. > It is an *assumption* that the power requirements must be proportional > the force against which it's shielding, and in fact I don't see the > reason for that assumption. > > > In the case of a permanent magnet motor, a stronger magnet > > implies more magnetic force aimed at the shield, so the shield will > > require more power to block the magnetic force. Consequently, a > > shield's power requirements are potentially unlimited. > > That is, again, an assumption, and whether it's correct for a given > shield depends on how the shield is implemented. > > In general, shields -- the physical sort -- require no power at all once > they're in place. It's only moving them into place and moving them away > again that takes the power. In the case of orbo the putative shield is continually being moved into place from the point of view of the rotor magnets so it requires power. > > > > > Many materials are inherently invisible to magnets, since magnets are > > not drawn to them. However, the core in the coil is not inherently > > invisible, so it requires a cloak instead of shield. Unlike a shield, > > the power requirements of a cloak are limited since the intent is to > > only make the core appear "invisible" or "insensible" to the magnets. > > > > > > Or is this wrong? > > The distinction you're drawing between a "cloak" and a "shield" is > interesting but I think it hides the fundamental similarities between > this design and all magnetic shield perpmos. My terminology is meant to illuminate the difference between the orbo and all othermagnetically shielded perpetual mobiles. > They *all* share the very important trait of drawing no power (to > operate the motor) while the shield is stationary; only the effects > during shield motion really matter. Since there is relative motion between the putative shield and the rotor, you can't say it requires no power once it is "in place". > Furthermore, I'm not so sure that power requirements of this "shield" > are independent of the applied B field. The B field penetrates the coil > (as you pointed out) and certainly affects the core. Thus, in order for > the coil to block the action of the B field, it must totally overwhelm > the effect of the external field within the core. Otherwise, the field > of the core would be somewhat aligned with the field of the external > magnet, and they would continue interacting. > > Consequently, a stronger external magnet will necessarily require a > stronger internal field to overwhelm it. Check this link to p. 360 from the book _Introduction to Magnetic Materials_ By B. D. Cullity, C. D. Graham http://tiny.cc/FQicR If I read it correctly, it says that the applied magnetic field required to rotate the saturated field Ms could, depending on the material, be _infinitely small_! Therefore you do not need to overwhelm the field of the permenant magnets, and with the right materials, the field generated by the coils can be made as small as you want. This satisfies my definition of a cloak. > In fact, this may be part of what makes this thing so hard to analyze > from the scope traces -- the current put through the coil has been set > high enough to totally swamp the effect of the external field, not just > "barely suppress" it, and in consequence we've got a *very* large > "background signal" from which we're trying to pick out a very small > "shield shifting" signal. > > > > > > > >> Now, the other issue is warming of the core. As I understand it, > >> when the core is saturating, things are not behaving "elastically" > >> and some energy is being lost to heat. I *think* that amount is > >> different depending on whether the core starts out saturated (by > >> the external magnets) or doesn't. That heat must be measured to > >> get a full energy balance of the motor, and of course JLN hasn't > >> done that in this series of experiments. > > > > Any heat produced is part of the output energy so knowing this heat > > loss should support the claim of overunity rather than detract from > > it. > > Not true. > > Steorn's claim is that heat loss = electrical power in. > > That is true if the motor is not turning. > > The thing which I *think* may be true -- though the longer this > discussion goes on the less sure I am -- is that *LESS* heat is lost to > the cores during motor operation than when the motor is stopped. > > That is to say, it is waste heat which is being diverted to power > generation. The motor gets less hot while running than it would otherwise. > > This is what Bill Beaty was saying, also, if I understood him correctly. > > But after realizing that the reduced induction means there *must* be > more power going in when the coil is energized while the magnets are > close, and after realizing that I don't understand the saturation > phenomenon very well at all, I decided I'm not so sure. I sent part of > this off to a serious EE I know but I haven't heard back (and haven't > phoned him recently). If he has an interesting opinion I'll relay it. > > If I can figure out how to calculate the expected additional power cost > to energize the coils when the magnets are nearby I'll post it (but > don't hold your breath, I have no idea how to get a handle on that). Harry __________________________________________________________________ Looking for the perfect gift? Give the gift of Flickr! http://www.flickr.com/gift/
