Timeline for How is a higher torque achieved in a single phase cap-start cap-run motor?
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
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| Apr 14, 2018 at 15:21 | comment | added | Ph3ng | Once the motor gets going, the start winding isn't needed anymore since the motor is already rotating... So why keep it there? | |
| Apr 14, 2018 at 14:12 | comment | added | Transistor | Correct, there will be some phase shift but nowhere near 90°. Once the motor gets going the start winding generally isn't required at all. | |
| Apr 14, 2018 at 13:55 | comment | added | Petar | But looking at the schematic the starting winding stays connected and can't be disconnected from the circuit. The switch only cuts the connection to one of the capacitors. To run the motor with the max torque a 90° phase shift is needed but that as you said can't be really achieved during startup but there must be at least some current phase shift to be able to make the motor turn | |
| Apr 14, 2018 at 13:46 | comment | added | Transistor | Generally correct, but the capacitor won't give a 90° phase shift because the start coil will have both resistance and inductance. The result will be that the current will lead the voltage probably in the region of 20° or so while running and more - maybe up to 45° on start. (I have never taken measurements so check these numbers.) The motor could be designed to run the start winding indefinitely but generally, if the switch has been fitted, it is designed to run only for a second or two. | |
| Apr 14, 2018 at 13:37 | history | answered | Petar | CC BY-SA 3.0 |