Timeline for Why can't a superconductor make a DC motor self-sustaining?
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
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| Dec 24, 2012 at 13:44 | comment | added | Christopher James Huff | Electric motors convert electrical power to mechanical power, and work both ways...every electrical motor is a generator, and its motion produces a voltage that opposes the current through the motor. This is why stalled motors can draw lots of current and burn themselves out, and why a superconducting motor with no other losses would still have a voltage drop and require power input. Similarly, if you short circuit a motor, it becomes an electromagnetic brake...a superconducting motor with its terminals shorted together would actually resist rotation. | |
| Dec 17, 2012 at 1:45 | comment | added | N. Virgo | @Velox OK, I've edited in some of my comments. | |
| Dec 17, 2012 at 1:44 | history | edited | N. Virgo | CC BY-SA 3.0 |
edited in some material from the comments
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| Dec 16, 2012 at 16:45 | vote | accept | Vial | ||
| Dec 15, 2012 at 2:27 | comment | added | N. Virgo | ...but however it works, I'm confident that what happens is that the force that stops the current is due to the fact that the charges in the wire are moving through a magnetic field, which is different from electrical resistance. | |
| Dec 15, 2012 at 2:24 | comment | added | N. Virgo | @Velox this is a better question than I thought. Thermodynamically, what must happen is that the current drops to zero as the motor accelerates, as the energy in the circulating current gets converted into kinetic energy. Presumably this is because the acceleration causes the charges to experience a force component opposite to their direction of travel through the wire. However, after sitting down to think about it I've realised my electromagnetics is too rusty for me to be confident about the mechanism that causes this. I hope someone else will supply a good answer. | |
| Dec 15, 2012 at 1:22 | comment | added | Vial | When wouldn't it? Does the magnetic field break down or mutate into something unuseable? You know, a superconductor can sustain a zero volt, zero resistance current for quite some time. Nothing changes, the current runs like it would in a regular motor... but I don't see where the actual acceleration of the rotor decreases the current in the superconductor. I hope that makes more sence | |
| Dec 13, 2012 at 23:26 | comment | added | N. Virgo | Of course it would accelerate, and perform work, in exactly the same way that a normal motor would. If you mean "would it accelerate or perform work without needing a battery or other voltage source" then the answer is no - but in order to adequately explain why I need to have a better understanding of why you think it would. | |
| Dec 13, 2012 at 15:31 | comment | added | Vial | Why wouldn't the motor accelerate? Or perform work. If the current models that of a regular homopolar motor, what makes the superconducting one not accelerate. (Overcome risistance). I understand it isn't possible, I just want to know why. Thanks | |
| Dec 13, 2012 at 9:21 | history | answered | N. Virgo | CC BY-SA 3.0 |