Delayed Lenz or not?... post your explaination!

[gotoluc]

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]

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]

Luc:

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]

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]

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