My 1st Selfrunning Generator?

[nilrehob]

This took me by surprise!

Nine low-voltage coils in series are connected to a variac.
The sum of the EMF in the coils is ~5.5V
The yellow trace is the 10th unused coil.
The blue trace is the current measured across a 1 ohm resistor.
The purple trace is the output from the transformer.

When the output from the transformer is decreased below the EMF the current shifts and the rotor continues to run.

If You understand what's going on please explain!

https://www.youtube.com/watch?v=B3RmqJ7X2dg

/Hob

[tinman]

This took me by surprise!

Nine low-voltage coils in series are connected to a variac.
The sum of the EMF in the coils is ~5.5V
The yellow trace is the 10th unused coil.
The blue trace is the current measured across a 1 ohm resistor.
The purple trace is the output from the transformer.

When the output from the transformer is decreased below the EMF the current shifts and the rotor continues to run.

If You understand what's going on please explain!

https://www.youtube.com/watch?v=B3RmqJ7X2dg

/Hob

The magnets in your rotor is making it look like the current is shifting in phase. Your CVR is seeing two thing's-the voltage produced by the magnets on the rotor as they approach and leave the coil,and the current provided by the transformer. You can see this voltage/current relationship with the yellow trace that shows the back and forth swinging motion-this is your flywheel speeding up and slowing down.

Brad

[nilrehob]

Further details:

The four strands in each of the nine coils are in parallel.
The nine coils are in series.
The sum of the DC resistance in the nine coils is 2.8 ohm.
The sum of the inductance in the nine coils is 36 mH.
The coils have welding-rods as core.
The distance between coils-magnets is ~3mm.
There are 20 neo-magnets, all north.

The tenth coil is only connected to the scope as reference.

The sum of the EMF from the nine coils is 5.5V (3.9V RMS).

There is no Bedini circuit connected to any coil.

The variac secondary is connected to the nine coils.
The variac primary is connected to the grid.
The grid is 50Hz, the wheel spins at 150 RPM.

Since there are magnets and not a squirrel-cage there is no slip.
It is a synchronous motor/generator.
The wobbling is because the coils and the magnets are not that tightly coupled.
The motor has ceramic bearings.

When the variac is above EMF, the variac is running the wheel as a motor.
When the variac is below EMF, the wheel is a generator feeding the variac?

When the voltage from the variac is above the coils EMF there is positive torque.
When the voltage from the variac is below the coils EMF there should be negative torque.

Why does the wheel still run when the variac is at 2.5V RMS which is below the EMF of the coils?

/Hob

[MileHigh]

When the variac is above EMF, the variac is running the wheel as a motor.
When the variac is below EMF, the wheel is a generator feeding the variac?

When the voltage from the variac is above the coils EMF there is positive torque.
When the voltage from the variac is below the coils EMF there should be negative torque.

Why does the wheel still run when the variac is at 2.5V RMS which is below the EMF of the coils?

I looked at the clip and you can see how it is a synchronous motor.  However, if the rotor turns at the same speed when the variac is at 2.5 VRMS then one must assume that it is still a synchronous motor.  So in both cases assume that there is positive torque.  I am assuming that at the lower drive voltage it is easier for the rotor to "slip out" of sync with the powerline frequency.  In contrast, you can see how the rotor "bounces back and forth" on the "walls" when the drive voltage is high showing that it is locked at the synchronous drive frequency.

The real answer to your question requires a precise analysis of the timing diagram.  You appear to have the correct information and all of the required information on your scope display already.  You just have to look at the timing diagram for a complete single rotor magnet pass and analyze when positive torque, no torque, and negative torque is applied to the rotor.  Do the timing analysis for both the higher drive voltage and the low drive voltage.  It's interesting because the timings are different for the two cases, and presumably in both cases the rotor turns synchronously with the AC mains excitation.

You don't have to be high tech here.  Just take a pencil and some graph paper and sketch out the recorded waveforms and then also sketch out waveform that shows the position of the passing rotor magnet and also sketch out a virtual waveform for the torque on the passing rotor magnet.  You may need to account for more than one rotor magnet and more than one drive coil in your timing analysis.  You need to analyze this yourself, step by step.

If you do this properly for both cases, you should arrive at the conclusion that in both cases there is a net positive torque on the rotor.

It's not a "self running generator."  You are getting carried away.  Presumably in both cases the setup draws power from your AC excitation voltage source?  In both cases, some of that power draw goes into applying positive torque to the rotor to overcome friction to keep it turning.

[nilrehob]

It's not a "self running generator."  You are getting carried away.  Presumably in both cases the setup draws power from your AC excitation voltage source?  In both cases, some of that power draw goes into applying positive torque to the rotor to overcome friction to keep it turning.

Not carried away, just surprised & confused :-)

It is obvious that the motor consumes power, the voltage and the current have almost the same phase, but why/how does it work?
The variac has the same phase as the EMF but lower voltage, that's my puzzle.

/Hob