Thane Heins Perepiteia.

[PulsedPower]

@aether22
lol, I was probably replying to your PM at the same moment you were writing that very effective attention grabber.

@groundloop, if your rotor stops the instant that the coil is shorted then it may be due to insufficient inertia to overcome the strong torque peaks created by shorting the coil.

[Groundloop]

@PulsedPower,

Yes. It is Lentz law. But I was expecting the opposite due to the fact that my motor now has a soft Iron rotor where the magnets is glued. This soft Iron rotor is in direct magnetic contact with the motor axle. So I expected the bemf flux generated in the shorted coil to couple back into the motor thus canceling the Lentz effect. That did not happen in my setup.

Groundloop.

[PulsedPower]

@groundloop

That is the fun with uncharterd territory, the unexpected don't assume any reason for the effect, you might have some theories but only experimetation and measurement will narrow down the cause of this interesting effect. Anyway it may be that the accelleration effect due to any flux entering the motor is weak and it is totally swamped by the strong pulsating pull of the magnet to the shorted coil. The system that Thane was demonstrating had plenty of inerita compared to the pulstations of the magnets interacting with the coil pole pieces.

The other thing I noticed with Thanes setup was that it was a bench grinder, these typically have aluminium end closures meaning that any magnetic flux can easily enter the rotor, If I am not mistaken you motor has a pressed steel end closure which would act as a magnetic shield with an effectiveness that increases with thickness and permeability.

Thanes motor is also running with massive slip (98.5% @ 60 rpm) and may behave very differently to a motor running closer to its design slip.

[Groundloop]

@PulsedPower,

You are not paying attention to the information I post. My induction motor has a plastic cover over the rotor. This plastic cover is transparent to magnetic flux. On top of that I have a soft Iron plate that is in direct magnetic contact with the axle. The back of my motor consists of cast iron. In Thane's setup the magnetic flux is supposed to enter the axle of the motor. I can say that my motor has a better chance of getting the back emf flux in, than a motor that uses steel axle and cast aluminum.

I agree with you about the difference of a motor that runs at slow speeds vs full speed. If the Thane effect is only visible when using a motor at slow speeds then it will be impossible for my motor to show the effect at full speed. I will try to slow down my motor.

[EDIT] I checked and the back cover of my motor is cast aluminum. Cast aluminum is non-magnetic.

Groundloop.

[Heinstein]

Thane, your results are very interesting but here's a test for you, compare the speed with and without the coil present (when present have it open circuit).

WITHOUTH THE COIL YOU HAVE NO GENERATOR.
WITH THE 1 COIL YOU HAVE A GENERATOR WITH ALOT OF COGGING TORQUE.= X
PLACE ADDITIONAL COILS IN THE RIGHT PLACE AND THE COGGING TORQUE DECREASES
X / NUMBER OF COILS.

PLACE A HUGE CHUNK OF IRON NEAR THE ROTOR AND YOU HAVE A HYSTERISIS BRAKE.

Or alternatly with 2 coils present, neither shorted but one monitored for voltage, them remove the other one and see if the voltage on the monitored coil changes. (If it's higher with one then that makes sense since there are core losses that have been reduced but if it's higher with 2 then something might be up)

WHAT'S HIGHER VOLTAGE OR RPM?
TOTAL GENERATOR O/P VOLTAGE IS HIGHER WITH ADDITIONAL COILS USED.
SIMPLY ADDING ANOTHER COIL (IRON) WILL DECREASE THE SPEED (EVERYTHING ELSE BEING EQUAL) AND THE INDUCED VOLTAGE IN THE MONITORED COIL WILL GO DOWN AS A RESULT.

INCREASING THE NUMBER OF COILS INCREASES THE COGGING TORQUE UNLESS THEY ARE BALANCED AROUND THE ROTOR PROPERLY. ONE COMPENSATING FOR THE OTHER ETC.

IF ON THE OTHER HAND YOU PLACE ALL 8 OF MY COILS AT " 6 OCLOCK" ON MY ROTOR THE COGGING TORQUE WOULD BE SO HIGH THE 1/3 HP MOTOR WOULD NEVER TURN IT.

IF YOU NOTICE IN THE PICTURES LUC AND STEVE POSTED YOU WILL SEE TWO ADDITIONAL COILS ON THE INSIDE OF THE ROTOR - NEAR THE MOTOR. WHEN THESE COILS ARE EMPLOYED THE COGGING TORQUE INCREASES SO THAT THE EFFECT IS DECREASED BECAUSE I DIDN'T BALANCE THEM PROPERLY. SO I ONLY USE THEM TO SHOW THAT THE GENERATOR CAN EMPLOY COILS ON BOTH SIDES OF THE ROTOR WITH THE SAME
EFFECT I.E INCREASED SYSTEM SPEED WITH LOAD APPLIED.

THANE