Pretty much as expected but there are some issues with the "patter".
On 01/20/2010 11:27 AM, Esa Ruoho wrote: > http://www.youtube.com/watch?v=VYGSdUdONpw > says "Addendum to our video "Steorn's Orbo Electromagnetic Interaction > COP greater than 1"" > > here's "a" transcript.. sorry if i made mistakes, i dont understand what > "aii" is.. > ---- > What we are going to do today is to address some of the concern made > after the last experiment, which is to know whether or not a change in > the inductance of the coils due to the magnets on the rotors, induced a > changed, in the current, through the coils. > > this is a coil, and we are measuring its inductance with this LCR meter > so i am connecting two kelvin probes to it. > and as you can read, on the LCR meter, its inductance is 306millihenry - > now i'm going to apply a strong magnetic field to the coil and as you > can see, its inductance has dropped to, about fourty microhenry. That's inductance with zero current flowing through the coil. With a ferro core the inductance isn't constant, as a function of current. None the less, we can draw an interesting conclusion: Lower inductance means current rise time will be faster, and integral(I*V) is going to be larger. In other words, energy going into the system will be LARGER when the coil is energized while there is a magnet near the coil than when it is energized while there is not. The difference is small -- but the mechanical output of this motor is small, too. Sean doesn't calculate or measure the difference in this post, so we don't know how much of the work done by the motor this difference would account for. > -- next scene -- > connecting the coil to a dc power supply. > > the yellow trace on the scope is the current, and the blue trace is the > voltage across the coil, there's an offset on the current of 180 > milliamps, so that we can zoom on the trace, and the scale is 5 > milliamps per division, and the scale of the voltage is ten millivolts > per division. > > and going to stop the oscilloscope, so we can read the values. there is > 184milliamps and 14.25 millivolts across the coil. i'm applying a strong > magnetic field to the coil, so i am changing the inductance of the coil. > going to run… and stop the oscilloscope. now the values are > 184.4milliamps and 14.26 millivolts. > > -- next scene -- > to summarize: the inductance of the coil before the application of the > permanent magnet, is 306 millihenry, and after the application of a > permanent magnet its 40 microhenry > > the energy stored in the inductor is half ali (??) squared that's half Ell Eye squared > which before the application of the permanent magnet gives us 5.18 > millijoules, and after the application of the permanent magnet, gives us > 0.00068 millijoules, which is a variation of 99.9%. Bogus calculation. The energy stored in the inductor is L*I^2/2 when, and only when, L is constant, because in that case we have 1) V = L*dI/dt -- def of an inductor 2) dI = (V/L)*dt -- rearranged 3) I = (V/L) * T -- assuming V fixed, which is only true at low I, before circuit resistance and R*I become significant 4) dE = (V*I)*dt -- Increment of added energy 5) dE = (V^2/L)*T*dt -- Substitute (3) into (4) 6) E = V^2/L * T^2/2 -- Integral of (5), assuming V and L constant Substitute (3) [T = I*L/V] into (6) and we obtain 7) E = L * I^2 / 2 That's a sloppy derivation of the equation Sean was quoting. However, it's got enough detail to see that it's only valid, as I said, if L is constant; otherwise we don't get equation (6) when we integrate equation (5). In this case L isn't constant, it varies with current (as the core saturates), and the calculation required is a lot messier. Consequently the energy input is a lot messier, and the whole exercise is harder than Sean has made out. To find the energy going in and coming out, he needs to a) Integrate the power using an integrating power meter or the integral function on a fast scope (that gets electrical power in but doesn't tell us anything about losses in the core). In particular, the power going into the system during the time interval during which the current *would* *be* increasing in the case where there is no magnet near the inductor needs to be measured for that case *and* for the case where there *is* a magnet near the inductor, in order to determine the difference in energy input with "motor on" versus "motor off". b) Measure the heat generated in the core during coil turn-on and turn-off. That's so because the normal assumption that all the energy that goes into fighting the BEMF will come out again when the current is shut down isn't necessarily so when the core is being saturated. Unless those are done, and until the mechanical power out is measured or, at least, estimated, the power budget hasn't really been determined. > on the voltage and current, the voltage before the application of the PM > is 14.25 millivolts, after application of PM it's 14.26 millivolts, > which gives us a difference of 4.57 microvolts. > > on the current, the current before the application of PM is 184.1 > milliamps, after application of PM it's 184.45 milliamps, gives us a > difference of 355microamps. > > the variations in the voltage and current are insignificant and are > within the rate of measurement accurancy and in no way can account for > the significant change in the energy stored in the inductor. His calculation of the energy stored in the inductor was incorrect, of course, as we noted above. Furthermore he's neglected the fact that the energy budget of the inductor must take account of the mechanical motion of the external magnet, as part of the inductor's energy was provided (and/or removed) by the effect of the external magnet in saturating the core. That will show up as F*x mechanical energy in the magnet's motion. This is an extremely complex system and his posted analysis is incomplete. Consequently his conclusions may or may not be correct.
