First post here and my first doubt (safety concern)

[energy-librarian]

Hi, I am Alejandro, 43 years, from Uruguay, South America.
My question is: are permanent magnet motors out of control devices? I mean, how is the start/stop procedure? 
Of course I am not referring to motors that use electromagnetic shielding.

[gyulasun]

Hi Alejandro,

If I could design such permanent magnet motor, then I would build some of the magnets to be detachable on the stator parts or maybe would use iron plates of suitable sizes to insert into the possible air gap between rotor stator to block the interacting flux.

rgds,  Gyula

[spinn_MP]

Hi, I am Alejandro, 43 years, from Uruguay, South America.
My question is: are permanent magnet motors out of control devices? I mean, how is the start/stop procedure? 
Of course I am not referring to motors that use electromagnetic shielding.

Good point, safety comes first!

Yep, it seems that PMM's are quite dangerous devices - starting is not a problem, but stopping...?
Believe me, you wouldn't want to try to stop one of those beasts, after the start up....

It seems that almost all the successful inventors from the past vanished (have been vaporised?) while trying to stop their "permanent magnet motors"....




Just kidding, don't worry.. You'll be safe.

Maybe... But watch out the MiB's....


(Kidding again, of course...)

Welcome!

[TinselKoala]

There actually are some real safety concerns.

First, the material that NdBFe magnets are made from, is FLAMMABLE and TOXIC. If you try to grind or cut this material you are risking a FIRE that will emit very TOXIC fumes.

Second, the magnets themselves are a PINCH HAZARD. You can be severely injured if you let your fingers or other flesh come between two NdBFe magnets that are loose and flying around.

Third, rapidly rotating assemblies that contain NdBFe magnets should rely on MECHANICAL RESTRAINTS and MOUNTS for the magnets, NOT GLUE. Any adhesive can fail, and will usually do so at the worst possible time: when the device is spinning fast.

Fourth, NdBFe magnets are BRITTLE and will break or SPALL OFF tiny bits if they are allowed to snap together uncontrolled. These little bits will be RED-HOT, flying FAST, and can do serious damage. WEAR EYE PROTECTION.

Fifth, if you have small children or animals, BE SURE that they CANNOT SWALLOW any of your magnets. It can kill them, by causing intestinal adhesions or blockages.



One thing you will NOT have to worry about is "how to stop a runaway magnet motor".

[Jehoiakim]

If you wanted to "cap" the speed of rotation, you may want to investigate the the theory of operation of centrifugal governors - as the rotational speed increases, you could have the centrifugal force of the spinning governor increase friction on either the drive shaft or a flywheel (if so equipped) shaft to keep RPMs at a reasonable speed.

As for stopping it, perhaps a friction brake on the drive shaft or the flywheel shaft.

Or, dunk the entire PMM into water - I'm sure the 1500% increase in the operating environment's viscosity will have the desired effect.