The new generator no effect counter B. EMF part 2 ( Selfrunning )

[MileHigh]

Luc:

I appreciate your effort and honest opinion. I'm sure if we all work together in a supportive way to better understand how to best test and deal with this kind of effect we will get there.

You mentioned flywheel, how about I add a flywheel above the C core?... would that not smooth the cogging so we would get more stable power readings?

You are welcome.  There is no point in adding a flywheel to the C-core if you are still driving it with the drill press motor.  I am assuming the electrical-in-to-mechanical-out efficiency of the drill press setup is always an unknown variable within the limitations of your testing and measuring environment, no matter what.  For sure the efficiency will change at different speeds and loads.

The thought-experiment flywheel would be a big metal flywheel, say about 50 pounds in weight and say two or three feet in diameter.  It would be on a very high performance bearing so that it would take a very long time for an unloaded spin-down.  There would be a series of tiny magnets or optical markings on the edge of the flywheel so you could record ticks to measure the deceleration.  You would mount the C-core rotor on the flywheel and then move the generator/stator into position and start recording the ticks.

I can imagine something like mounting the fancy flywheel + bearing into the chuck of a lathe.  Then you mount the stator/generator assembly in other the part of the lathe for holding your workpiece.  Sorry my lathe vocabulary sucks.  I marked up a pic, please see attached.

MileHigh

[PhysicsProfessor]

Tinman noted:

Im looking a lot deeper into this delayed magnetic field effect,and as you will see in my next video,i have an induced magnetic field that comes from !i dont know where! lol.-Advanced and delayed magnetic fields will be my new topic-watch for it.[/size]

The "delayed magnetic field effect" and induced B fields are of great interest.  Looking forward to your vid.

[MileHigh]

Quote:- MH


Note that you have two conflicting trends.  When you add a load resistor in theory the power draw from the prime mover increases.  In reality that does happen.  But at the same time, adding a load resistor results in current flow, and that reduces the cogging resulting in a decrease in power draw from the motor.  Even though in theory the cogging is energy-neutral, in practice you can literally hear the increased stress on the system when the cogging is happening.  These two conflicting trends make it nearly impossible for you to get the real data that you are looking for.[/size]

[/size]
Unquote

Now I like to see the trees without the forest, just makes things simpler

I think the whole point is, Why does the cogging stop under load? and not when unloaded?

MH please explain that without covering those trees with a forest   or anyone else

thanks in advance

regards

Mike

There are different types of cogging.  Let's define some terms.  Let's say that a "push" is a push against the direction of the rotation of the prime mover so that it tries to slow the prime mover down.   Let's say that a "pull" is a pull in the direction of the rotation of the prime mover so that it tries to speed up the prime mover.   Let's assume that we are working with a standard pulse motor with magnets on the rotor and a single generator coil.  The generator coil may or may not have a ferrite core.

If you have a generator coil driving a load and no core, you get a "push-push" cogging.  The first push is the Lenz drag repulsion from the magnet approaching the generator coil and the second push is the Lenz drag attraction from the magnet leaving the generator coil.

I have seen clips with this setup where load resistor is such that it only draws a small amount of energy from the rotor for each magnet fly-by.  Then the tester changes the load resistor so the energy draw is very large.  You hear a "thwack! thwack! thwack!" as the rotor spins and before you know it the rotor stops.  That's because the generator coil is sucking up way more rotational energy out of the rotor than the drive coil of the pulse motor can supply.

So that is one type of cogging.  It's "push-push" cogging.  If the coupling between the rotor magnets and the generator coil is very good, and you choose a load resistor value that sucks a lot or energy per magnet pass, then you get "big-push-big-push" cogging and the pulse motor craps out and stops.

...continued...

[MileHigh]

Now let's look at the case where the there is a generator coil with a core, but there is no load resistor.   In this case, the rotor magnet is attracted as it approaches TDC of the generator coil and that's a pull.   When the rotor magnet passes TDC you get a push.

So in this case, you get a "pull-push" type of cogging.  This is in theory energy neutral.

In Luc's case, it's a "big-pull-big push."  This stresses the rotor and the stator assembly and you get mechanical hysteresis losses.  In other words it's like bending a coat hanger and the bending point gets hot.   However, my gut feel is telling me the main source of the losses are in the motor itself because the motor does not like being yanked around by the big-pull-big-push.

In Luc's case, when he disconnects the load resistor while the drill press is running you clearly hear the "thwack! thwack! thwack!" of the big-pull-big push cogging.

So why does the sound of the cogging go away when Luc's connects the load resistor?

In this case you have two things happening at the same time, the cogging from driving the load resistor and the cogging from the attraction to the "core."

From the load resistor:      big-push-big-push
Form the core attraction:   big-pull-big-push

The net result:                  "cancellation"-bigger-push

In other words, the Lenz drag from the rotor approaching TDC, and the attraction of the rotor to the "core" tend to cancel each other out.  This cancellation effect tends to mitigate the cogging.   Even through past TDC the Lenz drag and the rotor attraction add up and produce a bigger push, it's still a "smoother ride" for the rotor will less overall disturbance happening.

Your ears give you the reality check.  It's very obvious that the "thwack! thwack! thwack!" gets much louder and the electrical power draw of the drive motor goes up the moment Luc disconnects the load resostor.

MileHigh

[TinselKoala]

@MH: "Tailstock" is the word I think you are looking for...   

@ others: I've demonstrated how to obtain an accurate power dissipation figure for a rotor turning at any given RPM, if you know the rotational Moment of Inertia (MoI) of the rotor and can make a graph of the rotor speed vs. time. The power dissipation is proportional to the instantaneous slope of the deceleration curve as the rotor slows down, unpowered. Then, when the rotor is powered to maintain a steady speed, the power applied to the rotor is the same as the power dissipated by the unpowered rotor at that same speed. You can have your "generator" coils operational during the rundown testing, and this will take care of the complicating factors mentioned above, or you can have them inactive if you are only concerned with the mechanical power dissipation. A chart recorder and a sensitive RPM/rotor position monitoring system makes the job relatively easy, once you know the MoI of the rotor. But if you are careful and have a lot of patience you can plot the rundown curve by hand.
The rotational MoI can be calculated from the geometry and mass distribution of the rotor itself.

http://www.youtube.com/watch?v=PJavCZX_-PI