Timeline for Electric motors and change in flux
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Feb 14, 2014 at 12:59 | comment | added | Ray | @Eliza No, the magnetic field on the wire is not constant as long as the coil is rotating, since the direction of the flux lines always change with the angle of the coil as it rotates - If I understood your last question correctly. | |
| Feb 14, 2014 at 12:02 | comment | added | Ray | @Eliza As for the max velocity, even though it's a never possible case, since there will always be losses that could be counted as load, you are right there is no current. But if the motor slows down (as you might think for the no current), the back EMF (proportional with the velocity) reduces, thus the supply current will be excess again and make up for the loss in velocity, and with it increasing the back EMF and so on, to reach back the ideal condition. So with that said, it's not possible for the motor to slow down in this case. | |
| Feb 14, 2014 at 11:59 | comment | added | Eliza | Ok. I get it now. also, the magnetic force on the current carrying wire, is it also a constant value? | |
| Feb 14, 2014 at 11:55 | comment | added | Ray | @Eliza Yes, constant ω would cause the motor to act as a generator. Since the coil cross through the flux lines. If the coil's ω vary so will the back EMF. By resistance I meant all sorts of resistance, since this is not an ideal case. However, the resistance of the air is normally negligible compared to that from the bearings of the rotor (the moving part). | |
| S Feb 14, 2014 at 11:11 | history | suggested | Eliza | CC BY-SA 3.0 |
used latex
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| Feb 14, 2014 at 11:06 | review | Suggested edits | |||
| S Feb 14, 2014 at 11:11 | |||||
| Feb 14, 2014 at 11:03 | comment | added | Eliza | this was extremely helpful. Just a few things: does the coil in a motor rotate with a constant $\omega$ , if not, does this mean that the back emf will vary? Also, are you referring to air resistance when talking about friction losses? Finally, max velocity is reached when the two EMFs equal each other, however, in that case, there will be no current, no magnetic torque and thus how would the coil rotate? | |
| Feb 14, 2014 at 9:04 | history | answered | Ray | CC BY-SA 3.0 |