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Author Topic: Delayed Lenz or not?... post your explaination!  (Read 77571 times)

gotoluc

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Delayed Lenz or not?... post your explaination!
« on: December 17, 2014, 01:22:08 AM »
Hi everyone,

I'm starting this topic to further study the effects of a generator coil which causes no load to its prime mover once connected to a 1 Ohm resistive load.
It seems we have many views about what could be happening in such a coil and maybe together we can find an explanation we can all agree upon.

I made a video of a simple test device that demonstrates a coil I consider having this quality.
A sense coil has been carefully positioned in order for both coil sinewaves to be in phase which can also serves as a rotor magnet timing reference.
During the video I didn't verbally explain because of the prime mover noise. However, it should be clear to most who have experience on the matter that once the coil is placed under the 1 Ohm load there is next to no change in Frequency (motor RPM). What's also clear is there's a delay in phase once I adjust the scope probe voltage division.

So the question is, what causes current to delay in a resistive load and what is going on in the coil to cause such an effect?


Link to video: https://www.youtube.com/watch?v=A0N0-sxa09c

Regards

Luc

synchro1

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Re: Delayed Lenz or not?... post your explaination!
« Reply #1 on: December 17, 2014, 01:42:26 AM »
@Luc,

Very controversial topic. Thanks for re-opening the investigation with solid test results.

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #2 on: December 17, 2014, 02:29:16 AM »
Here are the clean scope shots seen in the video.

Luc

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #3 on: December 17, 2014, 02:41:28 AM »
Here is another test using a 12.5 Ohm resistor as load with 5 Volts RMS across it = 2 Watts Output with no effect to the prime mover.

First shot is open coil, second is under load.

Luc

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #4 on: December 17, 2014, 02:54:49 AM »
Luc:

It looks like when you nearly short out the coil with the one-ohm resistor, the "true load" is an unknown inductance in series with the resistance of one ohm.  It appears that the impedance of the inductance at your approximately 250 Hz excitation frequency is much higher than the one ohm of the resistor.  Therefore, the current flow is determined by the impedance of the inductance and you see the 90 degree phase shift lag.  Where the unknown inductance actually exists in the circuit is to be determined.

The next logical test if I can suggest something to you is to try load resistances of 100 ohms, 1K ohms, and 10K ohms.  The assumption is that when the load resistor is much larger than the impedance of the unknown inductance then the load resistor will predominate for determining the phase of the current and the phase shift will disappear.

If you want to "earn extra brownie points" then you could calculate the resistive losses in the coil wire, and the resistive losses in the load resistance, and therefore the total resistive losses in the (coil + load resistor) system.  For a typical pulse motor, it's the resistive losses in the system that will determine the stabilized RPM for the rotor, a.k.a. the "acceleration."

MileHigh

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #5 on: December 17, 2014, 03:06:52 AM »
Here is another test which is the maximum power output this coil can do using a 25 Ohm load @ 8.97 Volts RMS = 3.2 Watts
Any higher resistive load will start causing a load on the prime mover unless I could increase the RPM. However, the tool is at maximum RPM turning this small N42 1/2 inch ring magnet.

Luc

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #6 on: December 17, 2014, 03:13:44 AM »
Luc:

It looks like when you nearly short out the coil with the one-ohm resistor, the "true load" is an unknown inductance in series with the resistance of one ohm.  It appears that the impedance of the inductance at your approximately 250 Hz excitation frequency is much higher than the one ohm of the resistor.  Therefore, the current flow is determined by the impedance of the inductance and you see the 90 degree phase shift lag.  Where the unknown inductance actually exists in the circuit is to be determined.

The next logical test if I can suggest something to you is to try load resistances of 100 ohms, 1K ohms, and 10K ohms.  The assumption is that when the load resistor is much larger than the impedance of the unknown inductance then the load resistor will predominate for determining the phase of the current and the phase shift will disappear.

If you want to "earn extra brownie points" then you could calculate the resistive losses in the coil wire, and the resistive losses in the load resistance, and therefore the total resistive losses in the (coil + load resistor) system.  For a typical pulse motor, it's the resistive losses in the system that will determine the stabilized RPM for the rotor, a.k.a. the "acceleration."

MileHigh

Hi MH,

see my other posts (one is above yours) with 12.5 and 25 Ohm (below yours) load tests.

The coils DC Resistance is 1.5 Ohm and Inductance is 26 mH

Luc

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #7 on: December 17, 2014, 03:17:01 AM »
Luc:

Quote
Any higher resistive load will start causing a load on the prime mover

If you keep on increasing the value of the load resistor at some point the power draw has to start decreasing.   It doesn't really matter anyway if the prime mover slows down a bit.  You can just "jump past" the resistances that give you higher power outputs if you want to.  You notice you are also exploring the relationship between the value of the load resistance and the amount of power that actually goes into the load resistance.  Another issue that I have already mentioned is the efficiency of the coil in terms of power lost in the coil windings vs. the useful power that goes into the load resistor.  This is a forum about ENERGY, and any serious pulse motor builder should want to explore these issues.

I can see already from your new scope shots that the phase lag is decreasing as you increase the value of the load resistor.

MileHigh

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #8 on: December 17, 2014, 03:21:37 AM »
Hi MH,

see my other posts (one is above yours) with 12.5 and 25 Ohm (below yours) load tests.

The coils DC Resistance is 1.5 Ohm and Inductance is 26 mH

Luc

I don't want to jump the gun here, but with a 100-ohm load resistor the phase lag will probably nearly be gone.   With a 1K-ohm load resistor the phase lag will probably not be viewable on your scope display.

This is showing you that there is no "delayed Lenz effect."

MileHigh

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #9 on: December 17, 2014, 03:32:07 AM »
Luc:

I can see already from your new scope shots that the phase lag is decreasing as you increase the value of the load resistor.

MileHigh

Yes, this is exactly what happens. I have known this for several years. As you raise the Resistance, at a certain value it will start to affect the prime mover since the phase delay starts to reduce. But if you increase the RPM you can retard the phase.
Keep in mind this is a small coil I put together just for a quick demo. It's not at ideal levels but good enough to demonstrate the effect.

If I had a stronger magnet and larger wire gauge coil, we could easily have 10X the output. I agree, even though a larger resistance value starts affecting the prime mover, however, it continues to output more power. So it may take 25 Watts from the prime mover at one point but it would be delivering 100 Watts. So why not use this extra 75 Watts at no cost to the prime mover?

Luc

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #10 on: December 17, 2014, 03:39:57 AM »
I see that you have a ferrite core in the generator coil.  How far does the ferrite core extend into the generator coil?

gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #11 on: December 17, 2014, 03:44:20 AM »
I see that you have a ferrite core in the generator coil.  How far does the ferrite core extend into the generator coil?

It's all the way in the coil.

Luc

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #12 on: December 17, 2014, 03:51:23 AM »
Okay thanks.  I was wondering if it only extended part way.  If it only extended part way then that might be an explanation for the unknown inductance.  It could be coming from the back of the coil if the ferrite was only half-way through the coil.

Your open-circuit Vrns for the generator coil is 11.7 volts.  Therefore if you tried a load resistor of 100 ohms the power into the load resistor will only be about 1.37 watts.  This will not slow down the prime mover.  However, you would need a 2-watt 100-ohm resistor.  It should be toasty warm to mildly hot if it is dissipating 1.37 watts.  The phase lag should mostly be gone with a 100-ohm load resistor.

MileHigh

MileHigh

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Re: Delayed Lenz or not?... post your explaination!
« Reply #13 on: December 17, 2014, 03:56:22 AM »
Yes, this is exactly what happens. I have known this for several years. As you raise the Resistance, at a certain value it will start to affect the prime mover since the phase delay starts to reduce. But if you increase the RPM you can retard the phase.
Keep in mind this is a small coil I put together just for a quick demo. It's not at ideal levels but good enough to demonstrate the effect.

Luc

If you increase the RPM you will increase the impedance of the unknown inductance and then you will see an increase in the phase delay.

Quote
If I had a stronger magnet and larger wire gauge coil, we could easily have 10X the output. I agree, even though a larger resistance value starts affecting the prime mover, however, it continues to output more power. So it may take 25 Watts from the prime mover at one point but it would be delivering 100 Watts. So why not use this extra 75 Watts at no cost to the prime mover?

Why would say that you could have 10X the output?  What is your reasoning for this?  How do you turn 25 watts into 100 watts?  What is your reasoning for this?


gotoluc

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Re: Delayed Lenz or not?... post your explaination!
« Reply #14 on: December 17, 2014, 04:18:29 AM »
If you increase the RPM you will increase the impedance of the unknown inductance and then you will see an increase in the phase delay.

Humm :-\ ... why do you keep writing unknown Inductance when I have already posted the DC Resistance and Inductance value?
http://overunity.com/15289/delayed-lenz-or-not-post-your-explaination/msg427939/#msg427939


Why would say that you could have 10X the output?  What is your reasoning for this?  How do you turn 25 watts into 100 watts?  What is your reasoning for this?

With ideal parameters,  larger wire coil, core and magnet it could easily do 10X the power output.
There's an ideal resistance value depending on the above geometry that outputs max Watts out even though it may take a little power from the prime mover, example 25 Watts. So a more ideal coil could output 100 Watts, so if you deduct the 25 watts it took from your prime mover you are still left with 75 Watts extra. NO?
So, why not develop and use this effect to make generators more efficient?

Luc