Am 20.09.2011 00:21, schrieb Joe Catania:
Ok, Peter. What I'm saying is I've run into this kind of thing before.
There was an electrical engineering professor on TheEEStory.com blog
who thought a patent was invalid and falsified because it showed a
fuse blowing at a current that (if it were DC) would be insufficient
to melt the fuse. I still haven't convinced him that skin effect is
the reason it blew.
The most common problem is that people dont know much abou their
measuring instruments and about the effects of crestfactor.
If the amperemeter doesnt measure tue effective value, then the
measurement is invalid.
If the fuse has a resistance of R then the momentanoeous power consumed
in the fuse is i^2*R
If there is a crest factor of 10, that means 1ms current and 9 ms no
current then the average power is P = R*i^2 /10.
However, the average current is i_avg= i/10. Therefore the average power
is not i_avg*U when we have a crest factor of 10 but it is much higher.
Look here: <http://en.wikipedia.org/wiki/Crest_factor>
Now the pitfalls are: Most cheap instrument measure the average and not
the root mean square average. They display only for DC and for
sinusoidal curves correctly because they are specially calibrated for it.
The better instruments have so-called true RMS measurement. Most people
dont know that in DC mode the average is measured and not the RMS. Often
the AC RMS is measured wrong if there is an DC component. Most
instruments are not made to measure unusual curveforms correctly. Any
instrument has a limitation for the crestfactor and frequency. If these
limits are exceeded they can display abstrusely wrong results. So with
unusual non-sinoidal waveforms, high crestfactor or rectified DC, you
get wrong results. You have to use a 2 channel oscilloscope or a very
expensive precision meter and this must be made exactly for the purpose.
(It is not sufficient to use expensive instruments, even these will
display wrong if they are not made for the specific purpose. If you use
the wrong instrument, you get wrong results)
I dont believe the skin effect has much influence at frequencies below
100 kHz. If the frequency is higher, the inductivity and capacitance of
the cables and resulting resonance transformation effects should have
much more influence to the measurement than the skin effect)
A good method to avoid errors in precision measurements is: Use two
different measuring methods and two instruments that are from different
vendors.
If the results dont match, then you can be sure, there is an unknown error.
Best,
Peter
He says that skin effect in the case of this fuse would be negligible
but he does not calculate it correctly, One must take into account all
the Fourier components in the pulse to get the proper effect. He only
traets the fundamental and is thus mislead. But a sawtooth wave has
harmonics that stretch theoretically to infinity. Although the
amplitudes of these harmonics decrease as their frequency increases
there is always the same net contribution to skin effect for each
frequency decade. In theory the upper limit of frequency should only
be limited by the electron plasma frequency. In other words, if there
were no such limitation the series would diverge. This is a known
property of the harmonic series (1 + 1/2 + 1/3 + 1/4...) which also
diverges and is related tothe sawtooth Fourier components. Where is
the paper mentioned?
----- Original Message -----
*From:* Peter Heckert <mailto:peter.heck...@arcor.de>
*To:* vortex-l@eskimo.com <mailto:vortex-l@eskimo.com>
*Sent:* Monday, September 19, 2011 5:21 PM
*Subject:* Re: [Vo]:Debunking Steorn Orbo
Am 19.09.2011 22:33, schrieb Joe Catania:
Now you are asking me to take it on faith from you. I find you
less convincing than Steorn.
Let me explain. All known rules about electricity and magnetism
are compatible with energy conservation.
It is therefore impossible to derive an extra energy
mathematically, basing on /known/ electromagnetic effects like
skin effect.
There must be an energy source.
I dont say that the effect is untrue. If it is true then it is not
an electromagnetic effect.
Possibly the Nickel core contains spurious Hydrogen atoms.
Nickel is magnetostrictive. Possibly the AC induces
magnetostrictive vibrations in the core or current in microscopic
superconductive spots and triggers hydrogen Nickel fusion.
The next locical thing to do would be to measure the frequency
depency of the effect. Why didnt they do this? Or might they have
done? Should I buy the paper? Tell me the price.
Best,
Peter
----- Original Message -----
*From:* Peter Heckert <mailto:peter.heck...@arcor.de>
*To:* vortex-l@eskimo.com <mailto:vortex-l@eskimo.com>
*Sent:* Monday, September 19, 2011 4:29 PM
*Subject:* Re: [Vo]:Debunking Steorn Orbo
Am 19.09.2011 22:22, schrieb Joe Catania:
I'm not going to take it on faith about the AC power being
less than DC. I've done these types of calculations before
and I can tell you they are not simple.
It is simple. The simplest way to calculate such problems is
to use the law of enery conservation ;-)
A sawtooth wave can generate some extremely high harmonics
which have a large skin effect. I'd need to see the formula
used to evaluate them.
;-)
