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

[gotoluc]

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]

@Luc,

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

[gotoluc]

Here are the clean scope shots seen in the video.

Luc

[gotoluc]

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]

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