Experiment on Viscous Remanent Magnetization (VRM) by JL Naudin
created on december 27, 2009 - JLN Labs - updated on January 20, 2010
Toutes les informations et schémas sont publiés gratuitement ( freeware ) et sont destinés à un usage personnel et non commercial
All informations and diagrams are published freely (freeware) and are intended for a private use and a non commercial use.

Cliquez ici pour la version FRANCAISE

The purpose of this test is to measure the Viscous Remanent Magnetization (VRM) decay of the toroïdal ferromagnetic core used in the Steorn Orbo motor v4.1 Vs the time.

When one rotor magnet, freely attracted by the ferromagnetic material of the toroïd, lives the core, the ferromagnetic material of the core remains temporarily magnetized with the opposite polarity of the leaving magne, due to the VRM effect. When the next rotor magnet approaches to this magnetized core, it will be more attracted by this temporarily magnetization during its approach and thus it will get more kinetic energy.

To conduct this experiment, I have used one of the Orbo rotor magnet. This magnet is maintained on a fix mounting base. Two samples of the ferromagnetic tore (grade: 3E25) used in the Orbo motor for the stator coils have been mounted on a rotating disk. The disk has been set in rotation by a simple brushless DC motor. The turn speed is precisely tuned by an Electronic Speed Controller (ESC). When the ferromagnetic core moves in front of the static magnet, an optical sensor detects the starting position and sends it to the scope. A moving Hall probe sensor UGN3503U (1mv/gauss) is used to measure the Viscous Remanent Magnetization level in the ferromagnetic core at a distance of 8 mm and along the circumference of the rotating disk. The VRM level can be recorded Vs the time frame...


Above, the full setup used to conduct the Viscous Remanent Magnetization experiment.


A detailled vue of the main parts used, you may notice the ferromagnetic cores (3E25) and the NdFeB magnet that I have used in my Orbo motor.
In this experiment the magnet is fixed and the previous ferromagnetic toroïdal cores, used as the stator in the Orbo motor, are rotating.
This allows a better setup to measure the VRM Vs the time frame with the Hall probe.


The rotating disk which contains the ferromagnetic cores is set in motion with a brushless DC motor.
The turn speed is precisely tuned with an Electronic Speed Controller (ESC).


Above, the ferromagnetic core is moving in front of the magnet and becomes magnetized.
You may see the synchro window in front of the optical sensor.


Above: the second type of ferromagnetic core tested, the 4C65 (µ:125)


The measured time delay is precisely measured by the scope and the VRM level is noted.

Two differents ferromagnetics cores have been tested, the 3E25 (µ:6000) and the 4C65 (µ:125)


Above, the VRM curves for the 4C65 core

You will find the full video of the test below :


Above, a detailled view of the VRM curve for the core 3E25

To summarize

This very interesting experiment shows that, in the Steorn Orbo motor, while the rotor magnet is freely attracted by the toroidal stator coil, the magnet is able to gain a kinetic energy boost due to Viscous Remanent Magnetization of the ferromagnetic core brought by the previous leaving magnet. The time of the VRM decay, and thus the rotor turn speed, is very important in this case to have a chance to get free energy from this process and its tuning is critical and also the choice of ferromagnetic material...

Interesting documents :

Email : JNaudin509@aol.com

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