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Author Topic: Reactive power - Reactive Generator research from GotoLuc - discussion thread  (Read 362103 times)

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #585 on: February 04, 2014, 12:00:30 PM »
If you have a phase shift between voltage and current... which apparently you do... is it still legitimate simply to multiply RMS voltage by RMS current to get a power figure?

I think Itsu's scope is multiplying the instantaneous samples of current and voltage.  He should have simply written  (Ch1 * Ch4),  (Ch3 * Ch4),  (Ch2 * Ch4), etc...

I hope, his scope only displays the RMS averages for each channel but makes multiplications for each sample.
I'm not sure what type of average his math channel is displaying/applying to the results of these multiplications  ...I think it's an arithmetical mean - not RMS, because it displays the word "mean".

verpies,

not sure what the scope is using, i can try to use PP values instead of RMS and see the difference in the math function, if any.
The documentation is not very enlightening about this subject either, i have to do some digging here i guess

Regards Itsu

 

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #586 on: February 04, 2014, 01:19:29 PM »

In the mean time i tried to replicate what Gotoluc is doing/measuring with this bifilar coil.
My bifilar coil is measured 1.3 Ohm and 127mH.

I tried to use the same setup as Luc did (625Hz square wave 10V rms as input)

I measure the voltage across and the current through the coil and using the math function (ch1 * Ch4) to show the power.
I am using a current probe which is set at 2mA/mV, meaning that the current (and the power) needs to be multiplied by 2

As i have a slightly higher ohms value in my coil, my signal on ch1 is somewhat stronger then yours.


Video here: http://www.youtube.com/watch?v=QgZcIavM_Oc&feature=youtu.be

Regards Itsu

verpies

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #587 on: February 04, 2014, 02:32:34 PM »
I tried to use the same setup as Luc did (625Hz square wave 10V rms as input)
That's a good place to recall, that the inductive reactance to a square wave is always 81% of the inductive reactance to a sine wave of the same frequency and RMS value.  See here.

Video here: http://www.youtube.com/watch?v=QgZcIavM_Oc&feature=youtu.be
The first scopeshot shows that the green current waveform curves up inside one of the blue ellipses...most likely due to beginnings of saturation.
In an ideal inductor the current waveform would never curve up like this.  See here.

The second scopeshot shows a discontinous current (a current spike) in an alleged RL circuit.
The current in an ideal RL circuit will never be discontinuous like this. 
In other words - current spikes are abnormal in an ideal inductor, even if that inductor is switched rapidly (...but voltage spikes are normal).

However, the interwinding parasitic capacitance is capable of creating such current spikes when stimulated by a rectangular waveform.
This parasititc capacitance will and does form a parallel LC tank with the inductance of the coil. This LC tank will and does ring/oscillate. 
If you know this ringing frequency and the inductance of the coil, then you can approximate this parasitic interwinding capacitance as C=1 / [ L(2πf)2].

The third annotated scopeshot shows the energy returned to the power supply (the SG) as the blue area above the red curve and the energy delivered by the power supply (the SG) as the white area under the red curve.

P.S.
How high are these current spikes anyway?
If I were you, I'd place the current probe after the voltage measuring probe, as a matter of principle.  Imagine, that the red crocodile clip is a small resistor...and the voltage sensed by the scope is subjected to the voltage drop of that resistor.  Now the voltage sensed depends on the current flowing and no longer reflects the true voltage output of the SG....in this case by μV.

gotoluc

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #588 on: February 04, 2014, 05:45:01 PM »
In the mean time i tried to replicate what Gotoluc is doing/measuring with this bifilar coil.
My bifilar coil is measured 1.3 Ohm and 127mH.

I tried to use the same setup as Luc did (625Hz square wave 10V rms as input)

I measure the voltage across and the current through the coil and using the math function (ch1 * Ch4) to show the power.
I am using a current probe which is set at 2mA/mV, meaning that the current (and the power) needs to be multiplied by 2

As i have a slightly higher ohms value in my coil, my signal on ch1 is somewhat stronger then yours.


Video here: http://www.youtube.com/watch?v=QgZcIavM_Oc&feature=youtu.be

Regards Itsu

Thanks itsu for the replication attempt and making a video to share your results.

Luc

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #589 on: February 04, 2014, 10:32:28 PM »
P.S.
How high are these current spikes anyway?

Thanks again verpies for this piece of information.

Here a picture of the current spike.
Again  times 2 = 144mA pp @ ringing frequency 7.2MHz

Regards Itsu

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #590 on: February 05, 2014, 10:21:13 PM »
This is briefly the tuning process, if you have questions please ask.

Gyula

Hi Gyula,

i followed your instructions, but i do not see a clear point where the right bulb starts to decrease while getting both coils closer together.
Still the left bulb is showing an increase in voltage (not visible anymore in the bulb itself because of the moved cores to the outside).

I have 7 cores in each coil, measuring 9.33mH each, see end of the video.

Video here: http://www.youtube.com/watch?v=gIOWQntycJA&feature=youtu.be

Regards Itsu


gyulasun

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #591 on: February 06, 2014, 12:28:05 AM »
Hi Gyula,

i followed your instructions, but i do not see a clear point where the right bulb starts to decrease while getting both coils closer together.
Still the left bulb is showing an increase in voltage (not visible anymore in the bulb itself because of the moved cores to the outside).

I have 7 cores in each coil, measuring 9.33mH each, see end of the video.

Video here: http://www.youtube.com/watch?v=gIOWQntycJA&feature=youtu.be

Regards Itsu

Hi Itsu,

Unfortunately, the dip at the original resonant frequency is small,  this means the change in the brightness can only be also very small and hard to notice by the eye, perhaps by monitoring the AC voltage by an analog voltage meter and not relying on the bulb brightness could help notice the dip by watching the needle.  Here is a dip in the center frequency of an overcoupled, mutually coupled two LC tanks: http://www.crystal-radio.eu/koppelinghoog.jpg

However, in your video I noticed the double peak behaviour which indicates overcoupling: I mean the blue trace which shows the voltage across the left hand side bulb, in video time between 3:02 and 3:10 or so the blue trace shows two peaks as you sweep the frequency in one direction, (I assume you did either upwards or downwards and you did not do it suddenly backwards just after an upwards peak).  And because of the coils are very close in that situation, please increase the distance between the coils and watch the blue trace when the two peaks disappear in the function of the separation, at a certain distance there should be only one peak remain in the blue trace (and not two) at the resonant frequency when you slowly sweep the generator. 
Sorry for this,  and I said the 5cm at random of course, coupling depends on several factors.

rgds,  Gyula

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #592 on: February 06, 2014, 09:48:27 AM »
so the blue trace shows two peaks as you sweep the frequency in one direction, (I assume you did either upwards or downwards and you did not do it suddenly backwards just after an upwards peak).

Correct.

Quote
please increase the distance between the coils and watch the blue trace when the two peaks disappear in the function of the separation, at a certain distance there should be only one peak remain in the blue trace (and not two) at the resonant frequency when you slowly sweep the generator. 

I did that lateron when moving away the both coils untill the blue line was flat.
However as i mentioned then, there is no light in the right bulb then, so i probably have the correct coupling distance, but the
coupling power is not enough to light the bulb which makes it in this case somewhat useless.

Anyway,  i get the picture, thanks.

Regards itsu

JulienVictor

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #593 on: February 06, 2014, 01:07:31 PM »
Dear

I am a highschool student and surely don't have that much knowledge as most of here have.
I have seen a video where gotoluc shows how he uses capacitors for having an overunity transformer, I drawed a picture of how I explain it simplfied, is this correct?

Kind regards, Julien

gyulasun

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #594 on: February 06, 2014, 02:57:21 PM »
Correct.

I did that lateron when moving away the both coils untill the blue line was flat.
However as i mentioned then, there is no light in the right bulb then, so i probably have the correct coupling distance, but the
coupling power is not enough to light the bulb which makes it in this case somewhat useless.

Anyway,  i get the picture, thanks.

Regards itsu

Hi Itsu,

Well, I believe the inherent difficulty in this setup is the use of incandescent bulbs to indicate the tuning process and the power relations...  While the bulbs are spectacular indicators and were introduced in the original video,  the tuning process which is problematic in itself (due to the mutual coupling) is further complicated by the nonlinearly changing bulb resistance as the strength of the current changes:  when the filament is cold or only hardly glow (when the input frequency is coming near to the resonance but not yet spot on), the filament resistance is low,  this is 'good' for input side on the left because input current is not influenced too much.  And the low resistance at right hand side is also good because it does not ruin too much the Q quality factor of the right hand side (series) L2C2 circuit, selectivity is preserved there.
Nearing to resonance and reaching it with the generator, the right hand side bulb's resistance increases to a maximum as it brightens up (this resistance increase is true for the input bulb too but its current is still low due to the resonant impedance of the input parallel L1C1 circuit) and at resonance the Q of the L2C2 circuit gets much reduced because the filament already has its higher value hot resistance in series with L2C2, so the resonant current in L2C2 is limited by the increased bulb resistance.
The best would be to use fix resistors of a few Ohms (say 1 to 5 Ohm) instead of the bulbs and watch current drops across them by the scope. Even so, very careful adjustments  are needed to get the most power out by inductive resonant coupling.

Thanks for all your efforts!

rgds, Gyula 

Farmhand

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #595 on: February 06, 2014, 05:48:17 PM »
I put together this crazy two phase generator setup.  ;D With a bit of maintenance on the motor it will be much more efficient. I was thinking i could do some experiments with it since the universal motor can be powered from a Battery with DC or with AC from the wall socket via a power meter and variac. And with two phases I could compare differences between two separate outputs at the same time. It can do 50/60 hz or even up to 80 or 100 Hz maybe. Voltage traces of the two phases is shown on the scope. It's not as loud as it sounds on the video.

Small two phase generator.
http://www.youtube.com/watch?v=9GSRtEKqh48

Cheers

verpies

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #596 on: February 06, 2014, 06:07:27 PM »
I put together this crazy two phase generator setup.  ;D
Is there anywhere I can see how that thing is constructed?

I could not hear and understand anything you said.  Is that tight bearing really the only component responsible for that racket?

verpies

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #597 on: February 06, 2014, 06:24:21 PM »
I am a high school student and surely don't have that much knowledge as most here have.
I have seen a video where gotoluc shows how he uses capacitors for having an overunity transformer, I drew a picture of how I explain it simplfied, is this correct?
I'd need to know more about the theory of operation of this circuit, such as the mutual inductance coefficient and the relationship of the primary LC tank resonance frequency [ 1/2π(LC)0.5 ] to the AC power supply frequency.  I did not read this thread from the beginning.

This appears to be a simplified version of of Itsu's experiment.  It is different though, because Itsu forms a parallel LC tank with the primary winding and a series LC tank with the secondary winding.  Your drawing shows only a series LC tank formed with the primary winding. A series LC tank achieves minimum impedance at resonance.

The way you had drawn the flux seems to be correct conceptually, but you must understand that 3 separate fluxes do not really form inside the ferromagnetic core.  Also windings that do not cover the whole core, create a flux leakage that looks as in the illustration below.  The opposing action of the secondary winding (due to Lenz law) actually expels the flux from under the secondary and aggravates the flux leakage outside of the core.

P.S.
What country are you from?

verpies

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #598 on: February 06, 2014, 06:44:29 PM »
Hi Gyula,
I followed your instructions, but i do not see a clear point where the right bulb starts to decrease while getting both coils closer together.
Did you ever do this measurement below?

If Itsu had searched for the precise primary LC resonance frequency (fP) under load  - while the secondary winding was connected only to the output bulb (no cap),...

itsu

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Re: Reactive power - Reactive Generator research from GotoLuc - discussion thread
« Reply #599 on: February 06, 2014, 07:02:56 PM »
Did you ever do this measurement below?


I did, and in response i wrote this:

Ok, i toke a quick shot at trying to get a flatline response on the parallel (left) bulb during resonance by manipulating the cores inside the coils.
This should also manipulate the inductance like decreasing the capacitance as mentioned by verpies, but its not working as expected.


I am lost now what was "not working as expected" (to many things going on  :) ), so i will retry your suggestions.

Regards Itsu