On Sunday 27 May 2018 15:03:22 a k wrote: > hi > i was thinking about problem that i got and have some ideas. > when one come close to the large motor - any motor - size of > motorcycle or small car , possible to notice that hair - start move. > like someone touching it. > right? > this is magnetic field touching. right? > such large motor always grounded. only super large business use such > motors. > i am talking about such large motor because no need to special > magnetometor to detect magnetic field- hair is enough . > what will happen if next to such motor put any coil or any metal body > -sheet metal etc? > the electricity will be generated. right? > if one will grounded this metallic part /coil next to large motor , > what will happen?
That is highly dependant on the motor. > that will effect large motor through magnetic field- without direct > contact to any large motor wiring etc. > my point. every motor will generate magnetic field - outside of motor > body. this magnetic field will have very strong robust effect on metal > object that close to motor as much as effect motor performance them > self. if some coil must be placed close to the motor then such motor > must be tune in same environment-situation. > > just a thinking And not. Whats basic is that any electric motor, is also a generator. But the common squirrel cage armature has no external circuits, its all a short circuit, so if its spinning, and a DC current is applied to the field windings, creating a magnetic field thru which the armature is turning, all its generated current goes into the shorting rings on the ends of the armature. Since it takes energy to generate that current, the motor turns into a braking system. A huge pulse of heat is developed, but the heating is over so fast because it has slowed, so its not often the heat is noticed. If the current is not turned off, and you try to turn the shaft, it will turn, but slowly like its full of mollasses. The external magnetic field is quite weak, again the motor is less efficient if it has high magnetic leakage, so its to the makers advantage to use a magnetic structure that minimizes this leakage since it causes the motor to need more power to develop x horsepower. Some PMDC motors have horrible leakage, but they just use bigger, stronger magnets to make up for that, its a one time cost the customer doesn't have to pay for. I haven't a clue where you were/are going with this line of thought, but just consider that there is no such thing as a perpetual motion machine, TANSTAAFL wins that argument every time. -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
